Import of Niels Provos' 20020312 ssh-complete.diff

PAM, Cygwin and OSF SIA will not work for sure

28 files changed, 2425 insertions, 109 deletions

diff --git a/Makefile.in b/Makefile.in
index b58250aae..38c1d381c 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1,4 +1,4 @@
-# $Id: Makefile.in,v 1.197 2002/02/26 19:24:22 mouring Exp $
+# $Id: Makefile.in,v 1.198 2002/03/13 01:47:54 djm Exp $
 
 prefix=@prefix@
 exec_prefix=@exec_prefix@
@@ -50,11 +50,11 @@ INSTALL_SSH_RAND_HELPER=@INSTALL_SSH_RAND_HELPER@
 
 TARGETS=ssh$(EXEEXT) sshd$(EXEEXT) ssh-add$(EXEEXT) ssh-keygen$(EXEEXT) ssh-keyscan${EXEEXT} ssh-agent$(EXEEXT) scp$(EXEEXT) ssh-rand-helper${EXEEXT} $(SFTP_PROGS)
 
-LIBSSH_OBJS=atomicio.o authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o cipher.o compat.o compress.o crc32.o deattack.o dh.o dispatch.o fatal.o mac.o hostfile.o key.o kex.o kexdh.o kexgex.o log.o match.o misc.o mpaux.o nchan.o packet.o radix.o rijndael.o entropy.o readpass.o rsa.o scard.o ssh-dss.o ssh-rsa.o tildexpand.o ttymodes.o uidswap.o uuencode.o xmalloc.o 
+LIBSSH_OBJS=atomicio.o authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o cipher.o compat.o compress.o crc32.o deattack.o dh.o dispatch.o fatal.o mac.o hostfile.o key.o kex.o kexdh.o kexgex.o log.o match.o misc.o monitor_fdpass.c monitor_wrap.c mpaux.o nchan.o packet.o radix.o rijndael.o entropy.o readpass.o rsa.o scard.o ssh-dss.o ssh-rsa.o tildexpand.o ttymodes.o uidswap.o uuencode.o xmalloc.o 
 
 SSHOBJS= ssh.o sshconnect.o sshconnect1.o sshconnect2.o sshtty.o readconf.o clientloop.o
 
-SSHDOBJS= sshd.o auth.o auth1.o auth2.o auth-chall.o auth2-chall.o auth-rhosts.o auth-options.o auth-krb4.o auth-pam.o auth2-pam.o auth-passwd.o auth-rsa.o auth-rh-rsa.o auth-sia.o sshpty.o sshlogin.o loginrec.o servconf.o serverloop.o md5crypt.o session.o groupaccess.o auth-skey.o auth-bsdauth.o
+SSHDOBJS= sshd.o auth.o auth1.o auth2.o auth-chall.o auth2-chall.o auth-rhosts.o auth-options.o auth-krb4.o auth-pam.o auth2-pam.o auth-passwd.o auth-rsa.o auth-rh-rsa.o auth-sia.o monitor.c monitor_mm.c sshpty.o sshlogin.o loginrec.o servconf.o serverloop.o md5crypt.o session.o groupaccess.o auth-skey.o auth-bsdauth.o
 
 MANPAGES        = scp.1.out ssh-add.1.out ssh-agent.1.out ssh-keygen.1.out ssh-keyscan.1.out ssh.1.out sshd.8.out sftp-server.8.out sftp.1.out
 MANPAGES_IN     = scp.1 ssh-add.1 ssh-agent.1 ssh-keygen.1 ssh-keyscan.1 ssh.1 sshd.8 sftp-server.8 sftp.1
diff --git a/auth.h b/auth.h
index c7175405d..9b5b19f6c 100644
--- a/auth.h
+++ b/auth.h
@@ -121,8 +121,8 @@ void	krb5_cleanup_proc(void *authctxt);
 #include "auth-pam.h"
 #include "auth2-pam.h"
 
-void    do_authentication(void);
-void    do_authentication2(void);
+Authctxt *do_authentication(void);
+Authctxt *do_authentication2(void);
 
 Authctxt *authctxt_new(void);
 void    auth_log(Authctxt *, int, char *, char *);
diff --git a/auth1.c b/auth1.c
index c2d99895f..c52f63897 100644
--- a/auth1.c
+++ b/auth1.c
@@ -26,8 +26,13 @@ RCSID("$OpenBSD: auth1.c,v 1.35 2002/02/03 17:53:25 markus Exp $");
 #include "session.h"
 #include "misc.h"
 #include "uidswap.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
 
 /* import */
+extern int use_privsep;
+extern int mm_recvfd;
+
 extern ServerOptions options;
 
 /*
@@ -355,12 +360,13 @@ do_authloop(Authctxt *authctxt)
  * Performs authentication of an incoming connection.  Session key has already
  * been exchanged and encryption is enabled.
  */
-void
+Authctxt *
 do_authentication(void)
 {
         Authctxt *authctxt;
-        struct passwd *pw;
+        struct passwd *pw = NULL, *pwent;
         u_int ulen;
+        int allowed;
         char *p, *user, *style = NULL;
 
         /* Get the name of the user that we wish to log in as. */
@@ -382,17 +388,26 @@ do_authentication(void)
         authctxt->style = style;
 
         /* Verify that the user is a valid user. */
-        pw = getpwnam(user);
-        if (pw && allowed_user(pw)) {
+        if (!use_privsep) {
+                pwent = getpwnam(user);
+                allowed = pwent ? allowed_user(pwent) : 0;
+        } else
+                pwent = mm_getpwnamallow(mm_recvfd, user, &allowed);
+        if (pwent && allowed) {
                 authctxt->valid = 1;
-                pw = pwcopy(pw);
+                pw = pwcopy(pwent);
         } else {
                 debug("do_authentication: illegal user %s", user);
                 pw = NULL;
         }
+        /* Free memory */
+        if (use_privsep)
+                pwfree(pwent);
+
         authctxt->pw = pw;
 
-        setproctitle("%s", pw ? user : "unknown");
+        setproctitle("%s%s", use_privsep ? " [net]" : "",
+            pw ? user : "unknown");
 
 #ifdef USE_PAM
         start_pam(pw == NULL ? "NOUSER" : user);
@@ -418,6 +433,5 @@ do_authentication(void)
         packet_send();
         packet_write_wait();
 
-        /* Perform session preparation. */
-        do_authenticated(authctxt);
+        return (authctxt);
 }
diff --git a/auth2.c b/auth2.c
index f2a801ecc..f661f8d7c 100644
--- a/auth2.c
+++ b/auth2.c
@@ -51,8 +51,13 @@ RCSID("$OpenBSD: auth2.c,v 1.85 2002/02/24 19:14:59 markus Exp $");
 #include "hostfile.h"
 #include "canohost.h"
 #include "match.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
 
 /* import */
+extern int use_privsep;
+extern int mm_recvfd;
+
 extern ServerOptions options;
 extern u_char *session_id2;
 extern int session_id2_len;
@@ -75,8 +80,8 @@ static void input_userauth_request(int, u_int32_t, void *);
 /* helper */
 static Authmethod *authmethod_lookup(const char *);
 static char *authmethods_get(void);
-static int user_key_allowed(struct passwd *, Key *);
-static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
+int user_key_allowed(struct passwd *, Key *);
+int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
 
 /* auth */
 static void userauth_banner(void);
@@ -109,7 +114,7 @@ Authmethod authmethods[] = {
  * loop until authctxt->success == TRUE
  */
 
-void
+Authctxt *
 do_authentication2(void)
 {
         Authctxt *authctxt = authctxt_new();
@@ -125,7 +130,8 @@ do_authentication2(void)
         dispatch_init(&dispatch_protocol_error);
         dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
         dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
-        do_authenticated(authctxt);
+
+        return(authctxt);
 }
 
 static void
@@ -182,10 +188,15 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
                 *style++ = 0;
 
         if (authctxt->attempt++ == 0) {
-                /* setup auth context */
+                /* setup auth context */
+                int allowed;
                 struct passwd *pw = NULL;
-                pw = getpwnam(user);
-                if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) {
+                if (!use_privsep) {
+                        pw = getpwnam(user);
+                        allowed = pw ? allowed_user(pw) : 0;
+                } else
+                        pw = mm_getpwnamallow(mm_recvfd, user, &allowed);
+                if (pw && allowed && strcmp(service, "ssh-connection")==0) {
                         authctxt->pw = pwcopy(pw);
                         authctxt->valid = 1;
                         debug2("input_userauth_request: setting up authctxt for %s", user);
@@ -198,10 +209,18 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
                         start_pam("NOUSER");
 #endif
                 }
-                setproctitle("%s", pw ? user : "unknown");
+                /* Free memory */
+                if (use_privsep)
+                        pwfree(pw);
+
+                setproctitle("%s%s", use_privsep ? " [net]" : "",
+                    pw ? user : "unknown");
                 authctxt->user = xstrdup(user);
                 authctxt->service = xstrdup(service);
                 authctxt->style = style ? xstrdup(style) : NULL;
+
+                if (use_privsep)
+                        mm_inform_authserv(mm_recvfd, service, style);
         } else if (strcmp(user, authctxt->user) != 0 ||
             strcmp(service, authctxt->service) != 0) {
                 packet_disconnect("Change of username or service not allowed: "
@@ -313,6 +332,8 @@ done:
 static int
 userauth_none(Authctxt *authctxt)
 {
+        int res = 0;
+
         /* disable method "none", only allowed one time */
         Authmethod *m = authmethod_lookup("none");
         if (m != NULL)
@@ -322,18 +343,16 @@ userauth_none(Authctxt *authctxt)
 
         if (authctxt->valid == 0)
                 return(0);
-
-#ifdef HAVE_CYGWIN
-        if (check_nt_auth(1, authctxt->pw) == 0)
-                return(0);
+        if (!authctxt->valid)
+                return (0);
+        if (use_privsep)
+#if defined(USE_PAM) || defined(HAVE_OSF_SIA)
+#error NOT IMPLEMENTED FOR PRIVSEP
 #endif
-#ifdef USE_PAM
-        return auth_pam_password(authctxt->pw, "");
-#elif defined(HAVE_OSF_SIA)
-        return 0;
-#else /* !HAVE_OSF_SIA && !USE_PAM */
-        return auth_password(authctxt, "");
-#endif /* USE_PAM */
+                res = mm_auth_password(mm_recvfd, "");
+        else
+                res = auth_password(authctxt, "");
+        return (res);
 }
 
 static int
@@ -348,18 +367,16 @@ userauth_passwd(Authctxt *authctxt)
                 log("password change not supported");
         password = packet_get_string(&len);
         packet_check_eom();
-        if (authctxt->valid &&
-#ifdef HAVE_CYGWIN
-            check_nt_auth(1, authctxt->pw) &&
+
+#if defined(HAVE_CYGWIN) || defined(USE_PAM) || defined(HAVE_OSF_SIA)
+#error NOT IMPLEMENTED FOR PRIVSEP
 #endif
-#ifdef USE_PAM
-            auth_pam_password(authctxt->pw, password) == 1)
-#elif defined(HAVE_OSF_SIA)
-            auth_sia_password(authctxt->user, password) == 1)
-#else /* !USE_PAM && !HAVE_OSF_SIA */
-            auth_password(authctxt, password) == 1)
-#endif /* USE_PAM */
-                authenticated = 1;
+        if (authctxt->valid) {
+                if (use_privsep)
+                        authenticated = mm_auth_password(mm_recvfd, password);
+                else
+                        authenticated = auth_password(authctxt, password);
+        }
         memset(password, 0, len);
         xfree(password);
         return authenticated;
@@ -467,12 +484,23 @@ userauth_pubkey(Authctxt *authctxt)
                 buffer_dump(&b);
 #endif
                 /* test for correct signature */
-                if (user_key_allowed(authctxt->pw, key) &&
-                    key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
-                        authenticated = 1;
+                authenticated = 0;
+                if (use_privsep) {
+                        if (mm_user_key_allowed(mm_recvfd, key) &&
+                            mm_key_verify(mm_recvfd,
+                                MM_USERKEY, NULL, NULL, key, sig, slen,
+                                buffer_ptr(&b), buffer_len(&b)) == 1)
+                                authenticated = 1;
+                } else {
+                        if (user_key_allowed(authctxt->pw, key) &&
+                            key_verify(key, sig, slen, buffer_ptr(&b),
+                                buffer_len(&b)) == 1)
+                                authenticated = 1;
+                }
                 buffer_clear(&b);
                 xfree(sig);
         } else {
+                int res = 0;
                 debug("test whether pkalg/pkblob are acceptable");
                 packet_check_eom();
 
@@ -484,7 +512,11 @@ userauth_pubkey(Authctxt *authctxt)
                  * if a user is not allowed to login. is this an
                  * issue? -markus
                  */
-                if (user_key_allowed(authctxt->pw, key)) {
+                if (use_privsep)
+                        res = mm_user_key_allowed(mm_recvfd, key);
+                else
+                        res = user_key_allowed(authctxt->pw, key);
+                if (res) {
                         packet_start(SSH2_MSG_USERAUTH_PK_OK);
                         packet_put_string(pkalg, alen);
                         packet_put_string(pkblob, blen);
@@ -572,9 +604,18 @@ userauth_hostbased(Authctxt *authctxt)
         buffer_dump(&b);
 #endif
         /* test for allowed key and correct signature */
-        if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) &&
-            key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
-                authenticated = 1;
+        authenticated = 0;
+        if (use_privsep) {
+                if (mm_hostbased_key_allowed(mm_recvfd, cuser, chost, key) &&
+                    mm_key_verify(mm_recvfd, MM_HOSTKEY, cuser, chost, key,
+                        sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
+                        authenticated = 1;
+        } else {
+                if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) &&
+                    key_verify(key, sig, slen, buffer_ptr(&b),
+                        buffer_len(&b)) == 1)
+                        authenticated = 1;
+        }
 
         buffer_clear(&b);
 done:
@@ -730,7 +771,7 @@ user_key_allowed2(struct passwd *pw, Key *key, char *file)
 }
 
 /* check whether given key is in .ssh/authorized_keys* */
-static int
+int
 user_key_allowed(struct passwd *pw, Key *key)
 {
         int success;
@@ -750,7 +791,7 @@ user_key_allowed(struct passwd *pw, Key *key)
 }
 
 /* return 1 if given hostkey is allowed */
-static int
+int
 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
     Key *key)
 {
diff --git a/bufaux.c b/bufaux.c
index 23bc0c814..64b9a26e9 100644
--- a/bufaux.c
+++ b/bufaux.c
@@ -221,6 +221,8 @@ buffer_put_string(Buffer *buffer, const void *buf, u_int len)
 void
 buffer_put_cstring(Buffer *buffer, const char *s)
 {
+        if (s == NULL)
+                fatal("buffer_put_cstring: s == NULL");
         buffer_put_string(buffer, s, strlen(s));
 }
 
diff --git a/cipher.c b/cipher.c
index 9e8f42f5e..5ddf819c4 100644
--- a/cipher.c
+++ b/cipher.c
@@ -541,3 +541,43 @@ evp_rijndael(void)
 #endif
         return (&rijndal_cbc);
 }
+
+/* 
+ * Exports an IV from the CipherContext required to export the key
+ * state back from the unprivileged child to the privileged parent
+ * process.
+ */
+
+void
+cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
+{
+        Cipher *c = cc->cipher;
+        u_char *civ = NULL;
+        int evplen;
+
+        switch (c->number) {
+        case SSH_CIPHER_SSH2:
+                evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
+                if (evplen == 0)
+                        return;
+                if (evplen != len)
+                        fatal("%s: wrong iv length %d != %d", __FUNCTION__,
+                            evplen, len);
+
+                if (strncmp(c->name, "aes", 3) == 0) {
+                        struct ssh_rijndael_ctx *aesc;
+
+                        aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
+                        if (aesc == NULL)
+                                fatal("ssh_rijndael_cbc: no context");
+                        civ = aesc->r_iv;
+                } else {
+                        civ = cc->evp.iv;
+                }
+                break;
+        default:
+                fatal("%s: bad cipher %d", __FUNCTION__, c->number);
+        }
+        memcpy(iv, civ, len);
+}
+
diff --git a/cipher.h b/cipher.h
index b3b0303c7..c7724469b 100644
--- a/cipher.h
+++ b/cipher.h
@@ -81,4 +81,6 @@ void	 cipher_cleanup(CipherContext *);
 void     cipher_set_key_string(CipherContext *, Cipher *, const char *, int);
 u_int    cipher_blocksize(Cipher *);
 u_int    cipher_keylen(Cipher *);
+
+void     cipher_get_keyiv(CipherContext *, u_char *, u_int);
 #endif                          /* CIPHER_H */
diff --git a/compress.c b/compress.c
index 3badbf452..dec96ba55 100644
--- a/compress.c
+++ b/compress.c
@@ -19,8 +19,8 @@ RCSID("$OpenBSD: compress.c,v 1.17 2001/12/29 21:56:01 stevesk Exp $");
 #include "zlib.h"
 #include "compress.h"
 
-static z_stream incoming_stream;
-static z_stream outgoing_stream;
+z_stream incoming_stream;
+z_stream outgoing_stream;
 static int compress_init_send_called = 0;
 static int compress_init_recv_called = 0;
 
diff --git a/kex.c b/kex.c
index bf8fd95b4..e5c0b0d00 100644
--- a/kex.c
+++ b/kex.c
@@ -43,6 +43,10 @@ RCSID("$OpenBSD: kex.c,v 1.47 2002/02/28 15:46:33 markus Exp $");
 
 #define KEX_COOKIE_LEN  16
 
+/* Use privilege separation for sshd */
+int use_privsep;
+int mm_recvfd;
+
 /* prototype */
 static void kex_kexinit_finish(Kex *);
 static void kex_choose_conf(Kex *);
diff --git a/kex.h b/kex.h
index 755bf332a..c99afaec0 100644
--- a/kex.h
+++ b/kex.h
@@ -111,6 +111,7 @@ struct Kex {
         char    *server_version_string;
         int     (*verify_host_key)(Key *);
         Key     *(*load_host_key)(int);
+        int     (*host_key_index)(Key *);
 };
 
 Kex     *kex_setup(char *[PROPOSAL_MAX]);
diff --git a/kexdh.c b/kexdh.c
index eaf497ca7..6256722ff 100644
--- a/kexdh.c
+++ b/kexdh.c
@@ -37,6 +37,12 @@ RCSID("$OpenBSD: kexdh.c,v 1.17 2002/02/28 15:46:33 markus Exp $");
 #include "packet.h"
 #include "dh.h"
 #include "ssh2.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
+
+/* Imports */
+extern int use_privsep;
+extern int mm_recvfd;
 
 static u_char *
 kex_dh_hash(
@@ -275,7 +281,12 @@ kexdh_server(Kex *kex)
 
         /* sign H */
         /* XXX hashlen depends on KEX */
-        key_sign(server_host_key, &signature, &slen, hash, 20);
+        if (use_privsep)
+                mm_key_sign(mm_recvfd,
+                    kex->host_key_index(server_host_key),
+                    &signature, &slen, hash, 20);
+        else
+                key_sign(server_host_key, &signature, &slen, hash, 20);
 
         /* destroy_sensitive_data(); */
 
diff --git a/kexgex.c b/kexgex.c
index 61896e6ed..3c811f337 100644
--- a/kexgex.c
+++ b/kexgex.c
@@ -38,6 +38,12 @@ RCSID("$OpenBSD: kexgex.c,v 1.20 2002/02/28 15:46:33 markus Exp $");
 #include "dh.h"
 #include "ssh2.h"
 #include "compat.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
+
+/* Imports */
+extern int use_privsep;
+extern int mm_recvfd;
 
 static u_char *
 kexgex_hash(
@@ -296,7 +302,11 @@ kexgex_server(Kex *kex)
                 fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
                     min, nbits, max);
 
-        dh = choose_dh(min, nbits, max);
+        /* Contact privileged parent */
+        if (use_privsep)
+                dh = mm_choose_dh(mm_recvfd, min, nbits, max);
+        else
+                dh = choose_dh(min, nbits, max);
         if (dh == NULL)
                 packet_disconnect("Protocol error: no matching DH grp found");
 
@@ -379,7 +389,11 @@ kexgex_server(Kex *kex)
 
         /* sign H */
         /* XXX hashlen depends on KEX */
-        key_sign(server_host_key, &signature, &slen, hash, 20);
+        if (use_privsep)
+                mm_key_sign(mm_recvfd, kex->host_key_index(server_host_key),
+                    &signature, &slen, hash, 20);
+        else
+                key_sign(server_host_key, &signature, &slen, hash, 20);
 
         /* destroy_sensitive_data(); */
 
@@ -390,6 +404,7 @@ kexgex_server(Kex *kex)
         packet_put_bignum2(dh->pub_key);        /* f */
         packet_put_string(signature, slen);
         packet_send();
+
         xfree(signature);
         xfree(server_host_key_blob);
         /* have keys, free DH */
diff --git a/key.c b/key.c
index cda91571a..fb6bff95b 100644
--- a/key.c
+++ b/key.c
@@ -801,3 +801,46 @@ key_verify(
                 break;
         }
 }
+
+/* Converts a private to a public key */
+
+Key *
+key_demote(Key *k)
+{
+        Key *pk;
+        
+        pk = xmalloc(sizeof(*pk));
+        pk->type = k->type;
+        pk->flags = k->flags;
+        pk->dsa = NULL;
+        pk->rsa = NULL;
+
+        switch (k->type) {
+        case KEY_RSA1:
+        case KEY_RSA:
+                if ((pk->rsa = RSA_new()) == NULL)
+                        fatal("key_demote: RSA_new failed");
+                if ((pk->rsa->e = BN_dup(k->rsa->e)) == NULL)
+                        fatal("key_demote: BN_dup failed");
+                if ((pk->rsa->n = BN_dup(k->rsa->n)) == NULL)
+                        fatal("key_demote: BN_dup failed");
+                break;
+        case KEY_DSA:
+                if ((pk->dsa = DSA_new()) == NULL)
+                        fatal("key_demote: DSA_new failed");
+                if ((pk->dsa->p = BN_dup(k->dsa->p)) == NULL)
+                        fatal("key_demote: BN_dup failed");
+                if ((pk->dsa->q = BN_dup(k->dsa->q)) == NULL)
+                        fatal("key_demote: BN_dup failed");
+                if ((pk->dsa->g = BN_dup(k->dsa->g)) == NULL)
+                        fatal("key_demote: BN_dup failed");
+                if ((pk->dsa->pub_key = BN_dup(k->dsa->pub_key)) == NULL)
+                        fatal("key_demote: BN_dup failed");
+                break;
+        default:
+                fatal("key_free: bad key type %d", k->type);
+                break;
+        }
+
+        return (pk);
+}
diff --git a/key.h b/key.h
index a2257731a..bc8b3d06b 100644
--- a/key.h
+++ b/key.h
@@ -58,6 +58,7 @@ struct Key {
 Key     *key_new(int);
 Key     *key_new_private(int);
 void     key_free(Key *);
+Key     *key_demote(Key *);
 int      key_equal(Key *, Key *);
 char    *key_fingerprint(Key *, enum fp_type, enum fp_rep);
 char    *key_type(Key *);
diff --git a/monitor.c b/monitor.c
new file mode 100644
index 000000000..b85790271
--- /dev/null
+++ b/monitor.c
@@ -0,0 +1,656 @@
+/*
+ * Copyright 2001 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD$");
+
+#include <openssl/dh.h>
+
+#include "ssh.h"
+#include "auth.h"
+#include "kex.h"
+#include "dh.h"
+#include "zlib.h"
+#include "packet.h"
+#include "auth-options.h"
+#include "sshpty.h"
+#include "channels.h"
+#include "session.h"
+#include "log.h"
+#include "monitor.h"
+#include "monitor_mm.h"
+#include "monitor_wrap.h"
+#include "monitor_fdpass.h"
+#include "xmalloc.h"
+#include "misc.h"
+#include "buffer.h"
+#include "bufaux.h"
+
+/* Imports */
+extern Newkeys *current_keys[];
+extern z_stream incoming_stream;
+extern z_stream outgoing_stream;
+extern int compat20;
+extern int mm_sendfd;
+
+/* State exported from the child */
+
+struct {
+        z_stream incoming;
+        z_stream outgoing;
+        u_char *keyin;
+        u_int keyinlen;
+        u_char *keyout;
+        u_int keyoutlen;
+} child_state;
+
+/* Prototype for authentication functions */
+
+int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
+int user_key_allowed(struct passwd *, Key *);
+Key *get_hostkey_by_index(int);
+
+void    session_pty_cleanup(void *);
+
+static Authctxt *authctxt;
+
+struct mon_table {
+        enum monitor_reqtype type;
+        int flags;
+        int (*f)(int, Buffer *);
+};
+
+#define MON_PROTOONE    0x0001  /* Used in protocol 1 */
+#define MON_PROTOTWO    0x0002  /* Used in protocol 2 */
+#define MON_AUTH        0x0004  /* Authentication Request */
+
+#define MON_BOTH        (MON_PROTOONE|MON_PROTOTWO)
+
+#define MON_PERMIT      0x1000  /* Request is permitted */
+
+struct mon_table mon_dispatch_proto20[] = {
+    {MONITOR_REQ_MODULI, MON_PROTOTWO, mm_answer_moduli},
+    {MONITOR_REQ_SIGN, MON_PROTOTWO, mm_answer_sign},
+    {MONITOR_REQ_PWNAM, MON_BOTH, mm_answer_pwnamallow},
+    {MONITOR_REQ_AUTHSERV, MON_BOTH, mm_answer_authserv},
+    {MONITOR_REQ_AUTHPASSWORD, MON_BOTH | MON_AUTH, mm_answer_authpassword},
+    {MONITOR_REQ_KEYALLOWED, MON_BOTH | MON_AUTH, mm_answer_keyallowed},
+    {MONITOR_REQ_KEYVERIFY, MON_BOTH | MON_AUTH, mm_answer_keyverify},
+    {0, 0, NULL}
+};
+
+struct mon_table mon_dispatch_postauth20[] = {
+    {MONITOR_REQ_MODULI, MON_PROTOTWO, mm_answer_moduli},
+    {MONITOR_REQ_SIGN, MON_PROTOTWO, mm_answer_sign},
+    {MONITOR_REQ_PTY, MON_BOTH, mm_answer_pty},
+    {MONITOR_REQ_TERM, MON_BOTH, mm_answer_term},
+    {0, 0, NULL}
+};
+
+struct mon_table mon_dispatch_proto15[] = {
+    {0, 0, NULL}
+};
+
+struct mon_table *mon_dispatch;
+
+/* Specifies if a certain message is allowed at the moment */
+
+void
+monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
+{
+        while (ent->f != NULL) {
+                if (ent->type == type) {
+                        ent->flags &= ~MON_PERMIT;
+                        ent->flags |= permit ? MON_PERMIT : 0;
+                        return;
+                }
+                ent++;
+        }
+}
+
+void
+monitor_permit_authentications(int permit)
+{
+        struct mon_table *ent = mon_dispatch;
+
+        while (ent->f != NULL) {
+                if (ent->flags & MON_AUTH) {
+                        ent->flags &= ~MON_PERMIT;
+                        ent->flags |= permit ? MON_PERMIT : 0;
+                }
+                ent++;
+        }
+}
+
+#define FD_CLOSEONEXEC(x) do { \
+        if (fcntl(x, F_SETFD, 1) == -1) \
+                fatal("fcntl(%d, F_SETFD)", x); \
+} while (0)
+
+void
+monitor_socketpair(int *pair)
+{
+        if (socketpair(PF_LOCAL, SOCK_STREAM, 0, pair) == -1)
+                fatal("%s: socketpair", __FUNCTION__);
+        FD_CLOSEONEXEC(pair[0]);
+        FD_CLOSEONEXEC(pair[1]);
+}
+
+Authctxt *
+monitor_child_preauth(int socket)
+{
+        debug3("preauth child monitor started");
+
+        if (compat20) {
+                mon_dispatch = mon_dispatch_proto20;
+
+                /* Permit requests for moduli and signatures */
+                monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
+                monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
+        } else
+                mon_dispatch = mon_dispatch_proto15;
+
+        authctxt = authctxt_new();
+
+        /* The first few requests do not require asynchronous access */
+        for (;;) {
+                if (monitor_read(socket, mon_dispatch))
+                        break;
+        }
+
+        debug("%s: %s has been authenticated by privileged process",
+            __FUNCTION__, authctxt->user);
+
+        if (compat20) {
+                mm_get_keystate(socket);
+        } else {
+                fatal("Use loose");
+        }
+
+        return (authctxt);
+}
+
+void
+monitor_child_postauth(int socket)
+{
+        if (compat20) {
+                mon_dispatch = mon_dispatch_postauth20;
+
+                /* Permit requests for moduli and signatures */
+                monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
+                monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
+                monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
+
+                if (!no_pty_flag)
+                        monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
+        } else
+                mon_dispatch = mon_dispatch_proto15;
+
+        for (;;) {
+                if (monitor_read(socket, mon_dispatch))
+                        break;
+        }
+}
+
+int
+monitor_read(int socket, struct mon_table *ent)
+{
+        Buffer m;
+        int ret;
+        u_char type;
+
+        buffer_init(&m);
+
+        mm_request_receive(socket, &m);
+        type = buffer_get_char(&m);
+
+        debug3("%s: checking request %d", __FUNCTION__, type);
+
+        while (ent->f != NULL) {
+                if (ent->type == type)
+                        break;
+                ent++;
+        }
+
+        if (ent->f != NULL) {
+                if (!(ent->flags & MON_PERMIT))
+                        fatal("%s: unpermitted request %d", __FUNCTION__,
+                            type);
+                ret = (*ent->f)(socket, &m);
+                buffer_free(&m);
+                return ret;
+        }
+
+        fatal("%s: unsupported request: %d\n", __FUNCTION__, type); 
+
+        /* NOTREACHED */
+        return (-1);
+}
+
+int
+mm_answer_moduli(int socket, Buffer *m)
+{
+        DH *dh;
+        int min, want, max;
+
+        /* Turn off requests for moduli */
+        monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 0);
+
+        min = buffer_get_int(m);
+        want = buffer_get_int(m);
+        max = buffer_get_int(m);
+
+        debug3("%s: got parameters: %d %d %d",
+            __FUNCTION__, min, want, max);
+        /* We need to check here, too, in case the child got corrupted */
+        if (max < min || want < min || max < want)
+                fatal("%s: bad parameters: %d %d %d",
+                    __FUNCTION__, min, want, max);
+
+        buffer_clear(m);
+
+        dh = choose_dh(min, want, max);
+        if (dh == NULL) {
+                buffer_put_char(m, 0);
+                return (0);
+        } else {
+                /* Send first bignum */
+                buffer_put_char(m, 1);
+                buffer_put_bignum2(m, dh->p);
+                buffer_put_bignum2(m, dh->g);
+                
+                DH_free(dh);
+        }
+        mm_request_send(socket, MONITOR_ANS_MODULI, m);
+        return (0);
+}
+
+int
+mm_answer_sign(int socket, Buffer *m)
+{
+        Key *key;
+        u_char *p;
+        u_char *signature;
+        u_int siglen, datlen;
+        int keyid;
+        
+        debug3("%s", __FUNCTION__);
+
+        keyid = buffer_get_int(m);      
+        p = buffer_get_string(m, &datlen);      
+
+        if ((key = get_hostkey_by_index(keyid)) == NULL)
+                fatal("%s: no hostkey from index %d", __FUNCTION__, keyid);
+        if (key_sign(key, &signature, &siglen, p, datlen) < 0)
+                fatal("%s: key_sign failed", __FUNCTION__);
+
+        debug3("%s: signature %p(%d)", __FUNCTION__, signature, siglen);
+
+        buffer_clear(m);
+        buffer_put_string(m, signature, siglen);
+
+        xfree(p);
+        xfree(signature);
+        
+        /* Turn on permissions for getpwnam */
+        monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
+
+        mm_request_send(socket, MONITOR_ANS_SIGN, m);
+        return (0);
+}
+
+/* Retrieves the password entry and also checks if the user is permitted */
+
+int
+mm_answer_pwnamallow(int socket, Buffer *m)
+{
+        char *login;
+        struct passwd *pwent;
+        int allowed;
+        
+        debug3("%s", __FUNCTION__);
+
+        if (authctxt->attempt++ != 0)
+                fatal("%s: multiple attempts for getpwnam", __FUNCTION__);
+
+        login = buffer_get_string(m, NULL);
+
+        /* XXX - probably latch the username here */
+        pwent = getpwnam(login);
+        authctxt->user = xstrdup(login);
+        setproctitle("%s [priv]", pwent ? login : "unknown");
+        xfree(login);
+
+        /* Allow service/style information on the auth context */
+        monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
+
+        buffer_clear(m);
+
+        if (pwent == NULL) {
+                buffer_put_char(m, 0);
+                mm_request_send(socket, MONITOR_ANS_PWNAM, m);
+                return (0);
+        }
+
+        /* Check if we permit this user */
+        allowed = allowed_user(pwent);
+
+        if (allowed) {
+                authctxt->pw = pwcopy(pwent);
+                authctxt->valid = 1;
+        }
+        buffer_put_char(m, allowed);
+        buffer_put_string(m, pwent, sizeof(struct passwd));
+        buffer_put_cstring(m, pwent->pw_name);
+        buffer_put_cstring(m, "*");
+        buffer_put_cstring(m, pwent->pw_gecos);
+        buffer_put_cstring(m, pwent->pw_class);
+        buffer_put_cstring(m, pwent->pw_dir);
+        buffer_put_cstring(m, pwent->pw_shell);
+
+        debug3("%s: sending MONITOR_ANS_PWNAM: %d", __FUNCTION__, allowed);
+        mm_request_send(socket, MONITOR_ANS_PWNAM, m);
+
+        return (0);
+}
+
+int
+mm_answer_authserv(int socket, Buffer *m)
+{
+        /* Disallow service/style information on the auth context */
+        monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 0);
+
+        monitor_permit_authentications(1);
+
+        authctxt->service = buffer_get_string(m, NULL);
+        authctxt->style = buffer_get_string(m, NULL);
+        if (strlen(authctxt->style) == 0) {
+                xfree(authctxt->style);
+                authctxt->style = NULL;
+        }
+
+        debug3("%s: service=%s, style=%s",
+            __FUNCTION__, authctxt->service, authctxt->style);
+
+        return (0);
+}
+
+int
+mm_answer_authpassword(int socket, Buffer *m)
+{
+        char *passwd;
+        int authenticated;
+
+        passwd = buffer_get_string(m, NULL);
+        /* Only authenticate if the context is valid */
+        authenticated = authctxt->valid && auth_password(authctxt, passwd);
+        memset(passwd, 0, strlen(passwd));
+        xfree(passwd);
+
+        buffer_clear(m);
+        buffer_put_int(m, authenticated);
+
+        debug3("%s: sending result %d", __FUNCTION__, authenticated);
+        mm_request_send(socket, MONITOR_ANS_AUTHPASSWORD, m);
+
+        /* Causes monitor loop to terminate if authenticated */
+        return (authenticated);
+}
+
+int
+mm_answer_keyallowed(int socket, Buffer *m)
+{
+        Key *key;
+        u_char *cuser, *chost, *blob;
+        u_int bloblen;
+        enum mm_keytype type = 0;
+        int allowed = 0;
+
+        debug3("%s entering", __FUNCTION__);
+        
+        type = buffer_get_int(m);
+        cuser = buffer_get_string(m, NULL);
+        chost = buffer_get_string(m, NULL);
+        blob = buffer_get_string(m, &bloblen);
+
+        key = key_from_blob(blob, bloblen);
+
+        debug3("%s: key_from_blob: %p", __FUNCTION__, key);
+
+        if (key != NULL && authctxt->pw != NULL) {
+                switch(type) {
+                case MM_USERKEY:
+                        allowed = user_key_allowed(authctxt->pw, key);
+                        break;
+                case MM_HOSTKEY:
+                        allowed = hostbased_key_allowed(authctxt->pw,
+                            cuser, chost, key);
+                        break;
+                default:
+                        fatal("%s: unknown key type %d", __FUNCTION__,
+                            type);
+                        break;
+                }
+                key_free(key);
+        }
+        xfree(chost);
+        xfree(cuser);
+        xfree(blob);
+
+        debug3("%s: key %p is %s",
+            __FUNCTION__, key, allowed ? "allowed" : "disallowed");
+
+        buffer_clear(m);
+        buffer_put_int(m, allowed);
+
+        mm_request_send(socket, MONITOR_ANS_KEYALLOWED, m);
+        return (0);
+}
+
+int
+mm_answer_keyverify(int socket, Buffer *m)
+{
+        Key *key;
+        u_char *signature, *data, *cuser, *chost, *blob;
+        u_int signaturelen, datalen, bloblen;
+        int type;
+        int verified = 0;
+
+        type = buffer_get_int(m);
+        cuser = buffer_get_string(m, NULL);
+        chost = buffer_get_string(m, NULL);
+        blob = buffer_get_string(m, &bloblen);
+        signature = buffer_get_string(m, &signaturelen);
+        data = buffer_get_string(m, &datalen);
+
+        key = key_from_blob(blob, bloblen);
+        if (key == NULL)
+                fatal("%s: bad public key blob", __FUNCTION__);
+
+        if (authctxt->pw == NULL || !user_key_allowed(authctxt->pw, key))
+                fatal("%s: user not allowed", __FUNCTION__);
+        verified = key_verify(key, signature, signaturelen, data, datalen);
+        debug3("%s: key %p signature %s",
+            __FUNCTION__, key, verified ? "verified" : "unverified");
+
+        key_free(key);
+        xfree(chost);
+        xfree(cuser);
+        xfree(blob);
+        xfree(signature);
+        xfree(data);
+                
+        buffer_clear(m);
+        buffer_put_int(m, verified);
+        mm_request_send(socket, MONITOR_ANS_KEYVERIFY, m);
+
+        return (verified);
+}
+
+int
+mm_answer_pty(int socket, Buffer *m)
+{
+        Session *s;
+        int res;
+
+        debug3("%s entering", __FUNCTION__);
+
+        buffer_clear(m);
+        s = session_new();
+        if (s == NULL)
+                goto error;
+        s->authctxt = authctxt;
+        s->pw = authctxt->pw;
+        res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
+        if (res == 0)
+                goto error;
+        fatal_add_cleanup(session_pty_cleanup, (void *)s);
+        pty_setowner(authctxt->pw, s->tty);
+
+        buffer_put_int(m, 1);
+        buffer_put_cstring(m, s->tty);
+        mm_request_send(socket, MONITOR_ANS_PTY, m);
+
+        mm_send_fd(mm_sendfd, s->ptyfd);
+        mm_send_fd(mm_sendfd, s->ttyfd);
+        return (0);
+
+ error:
+        if (s != NULL)
+                session_close(s);
+        buffer_put_int(m, 0);
+        mm_request_send(socket, MONITOR_ANS_PTY, m);
+        return (0);
+}
+
+int
+mm_answer_term(int socket, Buffer *req)
+{
+        debug3("%s: tearing down sessions", __FUNCTION__);
+
+        /* The child is terminating */
+        session_destroy_all();
+
+        return (1);
+}
+
+void
+mm_apply_keystate(struct mm_master *mm)
+{
+        /* XXX - delegate to child? */
+        set_newkeys(MODE_IN);
+        set_newkeys(MODE_OUT);
+
+        packet_set_keycontext(MODE_OUT, child_state.keyout);
+        xfree(child_state.keyout);
+        packet_set_keycontext(MODE_IN, child_state.keyin);
+        xfree(child_state.keyin);
+
+        memcpy(&incoming_stream, &child_state.incoming,
+            sizeof(incoming_stream));
+        memcpy(&outgoing_stream, &child_state.outgoing,
+            sizeof(outgoing_stream));
+        
+        /* Update with new address */
+        mm_init_compression(mm);
+}
+
+/* This function requries careful sanity checking */
+
+void
+mm_get_keystate(int socket)
+{
+        Buffer m;
+        u_char *blob, *p;
+        u_int bloblen, plen;
+
+        debug3("%s: Waiting for new keys", __FUNCTION__);
+
+        buffer_init(&m);
+        mm_request_receive_expect(socket, MONITOR_REQ_KEYEXPORT, &m);
+
+        blob = buffer_get_string(&m, &bloblen);
+        current_keys[MODE_OUT] = mm_newkeys_from_blob(blob, bloblen);
+        xfree(blob);
+
+        debug3("%s: Waiting for second key", __FUNCTION__);
+        blob = buffer_get_string(&m, &bloblen);
+        current_keys[MODE_IN] = mm_newkeys_from_blob(blob, bloblen);
+        xfree(blob);
+        
+        /* Now get sequence numbers for the packets */
+        packet_set_seqnr(MODE_OUT, buffer_get_int(&m));
+        packet_set_seqnr(MODE_IN, buffer_get_int(&m));
+
+        /* Get the key context */
+        child_state.keyout = buffer_get_string(&m, &child_state.keyoutlen);
+        child_state.keyin  = buffer_get_string(&m, &child_state.keyinlen);
+
+        debug3("%s: Getting compression state", __FUNCTION__);
+        /* Get compression state */
+        p = buffer_get_string(&m, &plen);
+        if (plen != sizeof(child_state.outgoing))
+                fatal("%s: bad request size", __FUNCTION__);
+        memcpy(&child_state.outgoing, p, sizeof(child_state.outgoing));
+        xfree(p);
+
+        p = buffer_get_string(&m, &plen);
+        if (plen != sizeof(child_state.incoming))
+                fatal("%s: bad request size", __FUNCTION__);
+        memcpy(&child_state.incoming, p, sizeof(child_state.incoming));
+        xfree(p);
+
+        buffer_free(&m);
+}
+
+
+/* Allocation functions for zlib */
+void *
+mm_zalloc(struct mm_master *mm, u_int ncount, u_int size)
+{
+        void *address;
+
+        address = mm_malloc(mm, size * ncount);
+
+        return (address);
+}
+
+void
+mm_zfree(struct mm_master *mm, void *address)
+{
+        mm_free(mm, address);
+}
+
+void
+mm_init_compression(struct mm_master *mm)
+{
+        outgoing_stream.zalloc = (alloc_func)mm_zalloc;
+        outgoing_stream.zfree = (free_func)mm_zfree;
+        outgoing_stream.opaque = mm;
+
+        incoming_stream.zalloc = (alloc_func)mm_zalloc;
+        incoming_stream.zfree = (free_func)mm_zfree;
+        incoming_stream.opaque = mm;
+}
diff --git a/monitor.h b/monitor.h
new file mode 100644
index 000000000..7568603fe
--- /dev/null
+++ b/monitor.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MONITOR_H_
+#define _MONITOR_H_
+
+enum monitor_reqtype {
+        MONITOR_REQ_MODULI, MONITOR_ANS_MODULI,
+        MONITOR_REQ_FREE, MONITOR_REQ_AUTHSERV,
+        MONITOR_REQ_SIGN, MONITOR_ANS_SIGN,
+        MONITOR_REQ_PWNAM, MONITOR_ANS_PWNAM,
+        MONITOR_REQ_AUTHPASSWORD, MONITOR_ANS_AUTHPASSWORD,
+        MONITOR_REQ_KEYALLOWED, MONITOR_ANS_KEYALLOWED,
+        MONITOR_REQ_KEYVERIFY, MONITOR_ANS_KEYVERIFY,
+        MONITOR_REQ_KEYEXPORT,
+        MONITOR_REQ_PTY, MONITOR_ANS_PTY,
+        MONITOR_REQ_TERM
+};
+
+struct monitor_req {
+        enum monitor_reqtype type;
+        void *address;
+        size_t size;
+};
+
+void monitor_socketpair(int *pair);
+
+struct Authctxt;
+struct Authctxt *monitor_child_preauth(int);
+void monitor_child_postauth(int);
+
+struct mon_table;
+int monitor_read(int, struct mon_table *);
+
+#endif /* _MONITOR_H_ */
diff --git a/monitor_fdpass.c b/monitor_fdpass.c
new file mode 100644
index 000000000..46087ae66
--- /dev/null
+++ b/monitor_fdpass.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2001 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD$");
+
+#include <sys/uio.h>
+
+#include "ssh.h"
+#include "log.h"
+#include "xmalloc.h"
+#include "misc.h"
+#include "monitor_fdpass.h"
+
+void
+mm_send_fd(int socket, int fd)
+{
+        struct msghdr msg;
+        char tmp[CMSG_SPACE(sizeof(int))];
+        struct cmsghdr *cmsg;
+        struct iovec vec;
+        char ch;
+
+        memset(&msg, 0, sizeof(msg));
+        msg.msg_control = (caddr_t)tmp;
+        msg.msg_controllen = CMSG_LEN(sizeof(int));
+        cmsg = CMSG_FIRSTHDR(&msg);
+        cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+        cmsg->cmsg_level = SOL_SOCKET;
+        cmsg->cmsg_type = SCM_RIGHTS;
+        *(int *)CMSG_DATA(cmsg) = fd;
+
+        vec.iov_base = &ch;
+        vec.iov_len = 1;
+        msg.msg_iov = &vec;
+        msg.msg_iovlen = 1;
+
+        if (sendmsg(socket, &msg, 0) == -1)
+                fatal("%s: sendmsg(%d)", __FUNCTION__, fd);
+}
+
+int
+mm_receive_fd(int socket)
+{
+        struct msghdr msg;
+        char tmp[CMSG_SPACE(sizeof(int))];
+        struct cmsghdr *cmsg;
+        struct iovec vec;
+        char ch;
+
+        memset(&msg, 0, sizeof(msg));
+        vec.iov_base = &ch;
+        vec.iov_len = 1;
+        msg.msg_iov = &vec;
+        msg.msg_iovlen = 1;
+        msg.msg_control = tmp;
+        msg.msg_controllen = sizeof(tmp);
+
+        if (recvmsg(socket, &msg, 0) == -1)
+                fatal("%s: recvmsg", __FUNCTION__);
+
+        cmsg = CMSG_FIRSTHDR(&msg);
+        if (cmsg->cmsg_type != SCM_RIGHTS)
+                fatal("%s: expected type %d got %d", __FUNCTION__,
+                    SCM_RIGHTS, cmsg->cmsg_type);
+        return (*(int *)CMSG_DATA(cmsg));
+}
diff --git a/monitor_fdpass.h b/monitor_fdpass.h
new file mode 100644
index 000000000..cb6b71c93
--- /dev/null
+++ b/monitor_fdpass.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MM_FDPASS_H_
+#define _MM_FDPASS_H_
+
+void mm_send_fd(int, int);
+int mm_receive_fd(int);
+
+#endif /* _MM_FDPASS_H_ */
diff --git a/monitor_mm.c b/monitor_mm.c
new file mode 100644
index 000000000..111c97d90
--- /dev/null
+++ b/monitor_mm.c
@@ -0,0 +1,329 @@
+/*
+ * Copyright 2001 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD$");
+
+#include <sys/mman.h>
+
+#include "ssh.h"
+#include "xmalloc.h"
+#include "log.h"
+#include "monitor_mm.h"
+
+static int
+mm_compare(struct mm_share *a, struct mm_share *b)
+{
+        return (a->address - b->address);
+}
+
+RB_GENERATE(mmtree, mm_share, next, mm_compare);
+
+static struct mm_share *
+mm_make_entry(struct mm_master *mm, struct mmtree *head,
+    void *address, size_t size)
+{
+        struct mm_share *tmp, *tmp2;
+
+        if (mm->mmalloc == NULL)
+                tmp = xmalloc(sizeof(struct mm_share));
+        else
+                tmp = mm_xmalloc(mm->mmalloc, sizeof(struct mm_share));
+        tmp->address = address;
+        tmp->size = size;
+
+        tmp2 = RB_INSERT(mmtree, head, tmp);
+        if (tmp2 != NULL)
+                fatal("mm_make_entry(%p): double address %p->%p(%d)",
+                    mm, tmp2, address, size);
+
+        return (tmp);
+}
+
+/* Creates a shared memory area of a certain size */
+
+struct mm_master *
+mm_create(struct mm_master *mmalloc, size_t size)
+{
+        void *address;
+        struct mm_master *mm;
+
+        if (mmalloc == NULL)
+                mm = xmalloc(sizeof(struct mm_master));
+        else
+                mm = mm_xmalloc(mmalloc, sizeof(struct mm_master));
+
+        /* 
+         * If the memory map has a mm_master it can be completely
+         * shared including authentication between the child
+         * and the client.
+         */
+        mm->mmalloc = mmalloc;
+
+        address = mmap(NULL, size, PROT_WRITE|PROT_READ, MAP_ANON|MAP_SHARED,
+            -1, 0);
+        if (address == MAP_FAILED)
+                fatal("mmap(%d)", size);
+
+        mm->address = address;
+        mm->size = size;
+
+        RB_INIT(&mm->rb_free);
+        RB_INIT(&mm->rb_allocated);
+
+        mm_make_entry(mm, &mm->rb_free, address, size);
+
+        return (mm);
+}
+
+/* Frees either the allocated or the free list */
+
+void
+mm_freelist(struct mm_master *mmalloc, struct mmtree *head)
+{
+        struct mm_share *mms, *next;
+
+        for (mms = RB_ROOT(head); mms; mms = next) {
+                next = RB_NEXT(mmtree, head, mms);
+                RB_REMOVE(mmtree, head, mms);
+                if (mmalloc == NULL)
+                        xfree(mms);
+                else
+                        mm_free(mmalloc, mms);
+        }
+}
+
+/* Destroys a memory mapped area */
+
+void
+mm_destroy(struct mm_master *mm)
+{
+        mm_freelist(mm->mmalloc, &mm->rb_free);
+        mm_freelist(mm->mmalloc, &mm->rb_allocated);
+
+        if (munmap(mm->address, mm->size) == -1)
+                fatal("munmap(%p, %d)", mm->address, mm->size);
+        if (mm->mmalloc == NULL)
+                xfree(mm);
+        else
+                mm_free(mm->mmalloc, mm);
+}
+
+void *
+mm_xmalloc(struct mm_master *mm, size_t size)
+{
+        void *address;
+
+        address = mm_malloc(mm, size);
+        if (address == NULL)
+                fatal("%s: mm_malloc(%d)", __FUNCTION__, size);
+        return (address);
+}
+
+
+/* Allocates data from a memory mapped area */
+
+void *
+mm_malloc(struct mm_master *mm, size_t size)
+{
+        struct mm_share *mms, *tmp;
+
+        if (size == 0)
+                fatal("mm_malloc: try to allocate 0 space");
+
+        size = ((size + MM_MINSIZE - 1) / MM_MINSIZE) * MM_MINSIZE;
+
+        RB_FOREACH(mms, mmtree, &mm->rb_free) {
+                if (mms->size >= size)
+                        break;
+        }
+
+        if (mms == NULL)
+                return (NULL);
+
+        /* Debug */
+        memset(mms->address, 0xd0, size);
+
+        tmp = mm_make_entry(mm, &mm->rb_allocated, mms->address, size);
+
+        /* Does not change order in RB tree */
+        mms->size -= size;
+        mms->address = (u_char *)mms->address + size;
+
+        if (mms->size == 0) {
+                RB_REMOVE(mmtree, &mm->rb_free, mms);
+                if (mm->mmalloc == NULL)
+                        xfree(mms);
+                else
+                        mm_free(mm->mmalloc, mms);
+        }
+
+        return (tmp->address);
+}
+
+/* Frees memory in a memory mapped area */
+
+void
+mm_free(struct mm_master *mm, void *address)
+{
+        struct mm_share *mms, *prev, tmp;
+
+        tmp.address = address;
+        mms = RB_FIND(mmtree, &mm->rb_allocated, &tmp);
+        if (mms == NULL)
+                fatal("mm_free(%p): can not find %p", mm, address);
+
+        /* Debug */
+        memset(mms->address, 0xd0, mms->size);
+
+        /* Remove from allocated list and insert in free list */
+        RB_REMOVE(mmtree, &mm->rb_allocated, mms);
+        if (RB_INSERT(mmtree, &mm->rb_free, mms) != NULL)
+                fatal("mm_free(%p): double address %p", mm, address);
+
+        /* Find previous entry */
+        prev = mms;
+        if (RB_LEFT(prev, next)) {
+                prev = RB_LEFT(prev, next);
+                while (RB_RIGHT(prev, next))
+                        prev = RB_RIGHT(prev, next);
+        } else {
+                if (RB_PARENT(prev, next) &&
+                    (prev == RB_RIGHT(RB_PARENT(prev, next), next)))
+                        prev = RB_PARENT(prev, next);
+                else {
+                        while (RB_PARENT(prev, next) &&
+                            (prev == RB_LEFT(RB_PARENT(prev, next), next)))
+                                prev = RB_PARENT(prev, next);
+                        prev = RB_PARENT(prev, next);
+                }
+        }
+
+        /* Check if range does not overlap */
+        if (prev != NULL && MM_ADDRESS_END(prev) > address)
+                fatal("mm_free: memory corruption: %p(%d) > %p",
+                    prev->address, prev->size, address);
+
+        /* See if we can merge backwards */
+        if (prev != NULL && MM_ADDRESS_END(prev) == address) {
+                prev->size += mms->size;
+                RB_REMOVE(mmtree, &mm->rb_free, mms);
+                if (mm->mmalloc == NULL)
+                        xfree(mms);
+                else
+                        mm_free(mm->mmalloc, mms);
+        } else
+                prev = mms;
+
+        if (prev == NULL)
+                return;
+
+        /* Check if we can merge forwards */
+        mms = RB_NEXT(mmtree, &mm->rb_free, prev);
+        if (mms == NULL)
+                return;
+
+        if (MM_ADDRESS_END(prev) > mms->address)
+                fatal("mm_free: memory corruption: %p < %p(%d)",
+                    mms->address, prev->address, prev->size);
+        if (MM_ADDRESS_END(prev) != mms->address)
+                return;
+
+        prev->size += mms->size;
+        RB_REMOVE(mmtree, &mm->rb_free, mms);
+
+        if (mm->mmalloc == NULL)
+                xfree(mms);
+        else
+                mm_free(mm->mmalloc, mms);
+}
+
+void
+mm_sync_list(struct mmtree *oldtree, struct mmtree *newtree,
+    struct mm_master *mm, struct mm_master *mmold)
+{
+        struct mm_master *mmalloc = mm->mmalloc;
+        struct mm_share *mms, *new;
+
+        /* Sync free list */
+        RB_FOREACH(mms, mmtree, oldtree) {
+                /* Check the values */
+                mm_memvalid(mmold, mms, sizeof(struct mm_share));
+                mm_memvalid(mm, mms->address, mms->size);
+
+                new = mm_xmalloc(mmalloc, sizeof(struct mm_share));
+                memcpy(new, mms, sizeof(struct mm_share));
+                RB_INSERT(mmtree, newtree, new);
+        }
+}
+
+void
+mm_share_sync(struct mm_master **pmm, struct mm_master **pmmalloc)
+{
+        struct mm_master *mm;
+        struct mm_master *mmalloc;
+        struct mm_master *mmold;
+        struct mmtree rb_free, rb_allocated;
+
+        debug3("%s: Share sync", __FUNCTION__);
+
+        mm = *pmm;
+        mmold = mm->mmalloc;
+        mm_memvalid(mmold, mm, sizeof(*mm));
+
+        mmalloc = mm_create(NULL, mm->size);
+        mm = mm_xmalloc(mmalloc, sizeof(struct mm_master));
+        memcpy(mm, *pmm, sizeof(struct mm_master));
+        mm->mmalloc = mmalloc;
+
+        rb_free = mm->rb_free;
+        rb_allocated = mm->rb_allocated;
+
+        RB_INIT(&mm->rb_free);
+        RB_INIT(&mm->rb_allocated);
+
+        mm_sync_list(&rb_free, &mm->rb_free, mm, mmold);
+        mm_sync_list(&rb_allocated, &mm->rb_allocated, mm, mmold);
+
+        mm_destroy(mmold);
+
+        *pmm = mm;
+        *pmmalloc = mmalloc;
+
+        debug3("%s: Share sync end", __FUNCTION__);
+}
+
+void
+mm_memvalid(struct mm_master *mm, void *address, size_t size)
+{
+        void *end = (u_char *)address + size;
+
+        if (address < mm->address)
+                fatal("mm_memvalid: address too small: %p", address);
+        if (end < address)
+                fatal("mm_memvalid: end < address: %p < %p", end, address);
+        if (end > (void *)((u_char *)mm->address + mm->size))
+                fatal("mm_memvalid: address too large: %p", address);
+}
diff --git a/monitor_mm.h b/monitor_mm.h
new file mode 100644
index 000000000..5b4b789ca
--- /dev/null
+++ b/monitor_mm.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MM_H_
+#define _MM_H_
+#include <sys/tree.h>
+
+struct mm_share {
+        RB_ENTRY(mm_share) next;
+        void *address;
+        size_t size;
+};
+
+struct mm_master {
+        RB_HEAD(mmtree, mm_share) rb_free;
+        struct mmtree rb_allocated;
+        void *address;
+        size_t size;
+
+        struct mm_master *mmalloc;      /* Used to completely share */
+
+        int write;              /* used to writing to other party */
+        int read;               /* used for reading from other party */
+};
+
+RB_PROTOTYPE(mmtree, mm_share, next, mm_compare);
+
+#define MM_MINSIZE              128
+
+#define MM_ADDRESS_END(x)       (void *)((u_char *)(x)->address + (x)->size)
+
+struct mm_master *mm_create(struct mm_master *, size_t);
+void mm_destroy(struct mm_master *);
+
+void mm_share_sync(struct mm_master **, struct mm_master **);
+
+void *mm_malloc(struct mm_master *, size_t);
+void *mm_xmalloc(struct mm_master *, size_t);
+void mm_free(struct mm_master *, void *);
+
+void mm_memvalid(struct mm_master *, void *, size_t);
+#endif /* _MM_H_ */
diff --git a/monitor_wrap.c b/monitor_wrap.c
new file mode 100644
index 000000000..798e9353d
--- /dev/null
+++ b/monitor_wrap.c
@@ -0,0 +1,538 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD$");
+
+#include <openssl/bn.h>
+#include <openssl/dh.h>
+
+#include "ssh.h"
+#include "dh.h"
+#include "kex.h"
+#include "buffer.h"
+#include "bufaux.h"
+#include "packet.h"
+#include "mac.h"
+#include "log.h"
+#include "zlib.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
+#include "xmalloc.h"
+#include "atomicio.h"
+#include "monitor_fdpass.h"
+#include "getput.h"
+
+/* Imports */
+extern Newkeys *newkeys[];
+extern z_stream incoming_stream;
+extern z_stream outgoing_stream;
+
+void
+mm_request_send(int socket, enum monitor_reqtype type, Buffer *m)
+{
+        u_char buf[5];
+        u_int mlen = buffer_len(m);
+
+        debug3("%s entering: type %d", __FUNCTION__, type);
+
+        PUT_32BIT(buf, mlen + 1);
+        buf[4] = (u_char) type;         /* 1st byte of payload is mesg-type */
+        if (atomicio(write, socket, buf, sizeof(buf)) != sizeof(buf))
+                fatal("%s: write", __FUNCTION__);
+        if (atomicio(write, socket, buffer_ptr(m), mlen) != mlen)
+                fatal("%s: write", __FUNCTION__);
+}
+
+void
+mm_request_receive(int socket, Buffer *m)
+{
+        u_char buf[4];
+        ssize_t res;
+        u_int msg_len;
+
+        debug3("%s entering", __FUNCTION__);
+
+        res = atomicio(read, socket, buf, sizeof(buf));
+        if (res != sizeof(buf))
+                fatal("%s: read: %d", __FUNCTION__, res);
+        msg_len = GET_32BIT(buf);
+        if (msg_len > 256 * 1024)
+                fatal("%s: read: bad msg_len %d", __FUNCTION__, msg_len);
+        buffer_clear(m);
+        buffer_append_space(m, msg_len);
+        res = atomicio(read, socket, buffer_ptr(m), msg_len);
+        if (res != msg_len)
+                fatal("%s: read: %d != msg_len", __FUNCTION__, res);
+}
+
+void
+mm_request_receive_expect(int socket, enum monitor_reqtype type, Buffer *m)
+{
+        u_char rtype;
+
+        debug3("%s entering: type %d", __FUNCTION__, type);
+
+        mm_request_receive(socket, m);
+        rtype = buffer_get_char(m);
+        if (rtype != type)
+                fatal("%s: read: rtype %d != type %d", __FUNCTION__,
+                    rtype, type);
+}
+
+DH *
+mm_choose_dh(int socket, int min, int nbits, int max)
+{
+        BIGNUM *p, *g;
+        int success = 0;
+        Buffer m;
+
+        buffer_init(&m);
+        buffer_put_int(&m, min);
+        buffer_put_int(&m, nbits);
+        buffer_put_int(&m, max);
+
+        mm_request_send(socket, MONITOR_REQ_MODULI, &m);
+
+        debug3("%s: waiting for MONITOR_ANS_MODULI", __FUNCTION__);
+        mm_request_receive_expect(socket, MONITOR_ANS_MODULI, &m);
+
+        success = buffer_get_char(&m);
+        if (success == 0)
+                fatal("%s: MONITOR_ANS_MODULI failed", __FUNCTION__);
+
+        if ((p = BN_new()) == NULL)
+                fatal("%s: BN_new failed", __FUNCTION__);
+        if ((g = BN_new()) == NULL) 
+                fatal("%s: BN_new failed", __FUNCTION__);
+        buffer_get_bignum2(&m, p);
+        buffer_get_bignum2(&m, g);
+
+        debug3("%s: remaining %d", __FUNCTION__, buffer_len(&m));
+        buffer_free(&m);
+
+        return (dh_new_group(g, p));
+}
+
+int
+mm_key_sign(int socket, int keyind, u_char **sigp, u_int *lenp,
+    u_char *data, u_int datalen)
+{
+        Buffer m;
+
+        debug3("%s entering", __FUNCTION__);
+
+        buffer_init(&m);
+        buffer_put_int(&m, keyind);
+        buffer_put_string(&m, data, datalen);
+
+        mm_request_send(socket, MONITOR_REQ_SIGN, &m);
+
+        debug3("%s: waiting for MONITOR_ANS_SIGN", __FUNCTION__);
+        mm_request_receive_expect(socket, MONITOR_ANS_SIGN, &m);
+        *sigp  = buffer_get_string(&m, lenp);
+        buffer_free(&m);
+
+        return (0);
+}
+
+struct passwd *
+mm_getpwnamallow(int socket, const char *login, int *allowed)
+{
+        Buffer m;
+        struct passwd *pw;
+        u_int pwlen;
+
+        debug3("%s entering", __FUNCTION__);
+
+        buffer_init(&m);
+        buffer_put_cstring(&m, login);
+
+        mm_request_send(socket, MONITOR_REQ_PWNAM, &m);
+
+        debug3("%s: waiting for MONITOR_ANS_PWNAM", __FUNCTION__);
+        mm_request_receive_expect(socket, MONITOR_ANS_PWNAM, &m);
+
+        *allowed  = buffer_get_char(&m);
+        if (*allowed == 0) {
+                buffer_free(&m);
+                return (NULL);
+        }
+        pw = buffer_get_string(&m, &pwlen);
+        if (pwlen != sizeof(struct passwd))
+                fatal("%s: struct passwd size mismatch", __FUNCTION__);
+        pw->pw_name = buffer_get_string(&m, NULL);
+        pw->pw_passwd = buffer_get_string(&m, NULL);
+        pw->pw_gecos = buffer_get_string(&m, NULL);
+        pw->pw_class = buffer_get_string(&m, NULL);
+        pw->pw_dir = buffer_get_string(&m, NULL);
+        pw->pw_shell = buffer_get_string(&m, NULL);
+        buffer_free(&m);
+
+        return (pw);
+}
+
+void
+pwfree(struct passwd *pw)
+{
+        xfree(pw->pw_name);
+        xfree(pw->pw_passwd);
+        xfree(pw->pw_gecos);
+        xfree(pw->pw_class);
+        xfree(pw->pw_dir);
+        xfree(pw->pw_shell);
+        xfree(pw);
+}
+
+/* Inform the privileged process about service and style */
+
+void
+mm_inform_authserv(int socket, char *service, char *style)
+{
+        Buffer m;
+
+        debug3("%s entering", __FUNCTION__);
+
+        buffer_init(&m);
+        buffer_put_cstring(&m, service);
+        buffer_put_cstring(&m, style ? style : "");
+
+        mm_request_send(socket, MONITOR_REQ_AUTHSERV, &m);
+
+        buffer_free(&m);
+}
+
+/* Do the password authentication */
+int
+mm_auth_password(int socket, char *password)
+{
+        Buffer m;
+        int authenticated = 0;
+
+        debug3("%s entering", __FUNCTION__);
+
+        buffer_init(&m);
+        buffer_put_cstring(&m, password);
+        mm_request_send(socket, MONITOR_REQ_AUTHPASSWORD, &m);
+
+        debug3("%s: waiting for MONITOR_ANS_AUTHPASSWORD", __FUNCTION__);
+        mm_request_receive_expect(socket, MONITOR_ANS_AUTHPASSWORD, &m);
+
+        authenticated = buffer_get_int(&m);
+
+        buffer_free(&m);
+
+        debug3("%s: user %sauthenticated", 
+            __FUNCTION__, authenticated ? "" : "not ");
+        return (authenticated);
+}
+
+int
+mm_key_allowed(int socket, enum mm_keytype type, char *user, char *host,
+    Key *key)
+{
+        Buffer m;
+        u_char *blob;
+        u_int len;
+        int allowed = 0;
+
+        debug3("%s entering", __FUNCTION__);
+
+        /* Convert the key to a blob and the pass it over */
+        if (!key_to_blob(key, &blob, &len))
+                return (0);
+
+        buffer_init(&m);
+        buffer_put_int(&m, type);
+        buffer_put_cstring(&m, user ? user : "");
+        buffer_put_cstring(&m, host ? host : "");
+        buffer_put_string(&m, blob, len);
+        xfree(blob);
+
+        mm_request_send(socket, MONITOR_REQ_KEYALLOWED, &m);
+
+        debug3("%s: waiting for MONITOR_ANS_KEYALLOWED", __FUNCTION__);
+        mm_request_receive_expect(socket, MONITOR_ANS_KEYALLOWED, &m);
+
+        allowed = buffer_get_int(&m);
+
+        buffer_free(&m);
+
+        return (allowed);
+}
+
+/* 
+ * This key verify needs to send the key type along, because the
+ * privileged parent makes the decision if the key is allowed
+ * for authentication.
+ */
+
+int
+mm_key_verify(int socket, enum mm_keytype type, char *user, char *host,
+    Key *key, u_char *sig, u_int siglen, u_char *data, u_int datalen)
+{
+        Buffer m;
+        u_char *blob;
+        u_int len;
+        int verified = 0;
+
+        debug3("%s entering", __FUNCTION__);
+
+        /* Convert the key to a blob and the pass it over */
+        if (!key_to_blob(key, &blob, &len))
+                return (0);
+
+        buffer_init(&m);
+        buffer_put_int(&m, type);
+        buffer_put_cstring(&m, user ? user : "");
+        buffer_put_cstring(&m, host ? host : "");
+        buffer_put_string(&m, blob, len);
+        buffer_put_string(&m, sig, siglen);
+        buffer_put_string(&m, data, datalen);
+        xfree(blob);
+
+        mm_request_send(socket, MONITOR_REQ_KEYVERIFY, &m);
+
+        debug3("%s: waiting for MONITOR_ANS_KEYVERIFY", __FUNCTION__);
+        mm_request_receive_expect(socket, MONITOR_ANS_KEYVERIFY, &m);
+
+        verified = buffer_get_int(&m);
+
+        buffer_free(&m);
+
+        return (verified);
+}
+
+/* Export key state after authentication */
+Newkeys *
+mm_newkeys_from_blob(u_char *blob, int blen)
+{
+        Buffer b;
+        int rlen;
+        Newkeys *newkey = NULL;
+        Enc *enc;
+        Mac *mac;
+        Comp *comp;
+
+        debug3("%s: %p(%d)", __FUNCTION__, blob, blen);
+#ifdef DEBUG_PK
+        dump_base64(stderr, blob, blen);
+#endif
+        buffer_init(&b);
+        buffer_append(&b, blob, blen);
+
+        newkey = xmalloc(sizeof(*newkey));
+        enc = &newkey->enc;
+        mac = &newkey->mac;
+        comp = &newkey->comp;
+
+        /* Enc structure */
+        enc->name = buffer_get_string(&b, NULL);
+        buffer_get(&b, &enc->cipher, sizeof(enc->cipher));
+        enc->enabled = buffer_get_int(&b);
+        enc->key_len = buffer_get_int(&b);
+        enc->block_size = buffer_get_int(&b);
+        enc->key = xmalloc(enc->key_len);
+        buffer_get(&b, enc->key, enc->key_len);
+        enc->iv = xmalloc(enc->block_size);
+        buffer_get(&b, enc->iv, enc->block_size);
+
+        if (enc->name == NULL || cipher_by_name(enc->name) != enc->cipher)
+                fatal("%s: bad cipher name %s or pointer %p", __FUNCTION__,
+                    enc->name, enc->cipher);
+
+        /* Mac structure */
+        mac->name = buffer_get_string(&b, NULL);
+        if (mac->name == NULL || mac_init(mac, mac->name) == -1)
+                fatal("%s: can not init mac %s", __FUNCTION__, mac->name);
+        mac->enabled = buffer_get_int(&b);
+        mac->key = xmalloc(mac->key_len);
+        buffer_get(&b, mac->key, mac->key_len);
+
+        /* Comp structure */
+        comp->type = buffer_get_int(&b);
+        comp->enabled = buffer_get_int(&b);
+        comp->name = buffer_get_string(&b, NULL);
+
+        rlen = buffer_len(&b);
+        if (rlen != 0)
+                error("newkeys_from_blob: remaining bytes in blob %d", rlen);
+        buffer_free(&b);
+        return (newkey);
+}
+
+int
+mm_newkeys_to_blob(int mode, u_char **blobp, u_int *lenp)
+{
+        Buffer b;
+        int len;
+        u_char *buf;
+        Enc *enc;
+        Mac *mac;
+        Comp *comp;
+        Newkeys *newkey = newkeys[mode];
+
+        debug3("%s: converting %p", __FUNCTION__, newkey);
+
+        if (newkey == NULL) {
+                error("%s: newkey == NULL", __FUNCTION__);
+                return 0;
+        }
+        enc = &newkey->enc;
+        mac = &newkey->mac;
+        comp = &newkey->comp;
+
+        buffer_init(&b);
+        /* Enc structure */
+        buffer_put_cstring(&b, enc->name);
+        /* The cipher struct is constant and shared, you export pointer */
+        buffer_append(&b, &enc->cipher, sizeof(enc->cipher));
+        buffer_put_int(&b, enc->enabled);
+        buffer_put_int(&b, enc->key_len);
+        buffer_put_int(&b, enc->block_size);
+        buffer_append(&b, enc->key, enc->key_len);
+        packet_get_keyiv(mode, enc->iv, enc->block_size);
+        buffer_append(&b, enc->iv, enc->block_size);
+
+        /* Mac structure */
+        buffer_put_cstring(&b, mac->name);
+        buffer_put_int(&b, mac->enabled);
+        buffer_append(&b, mac->key, mac->key_len);
+
+        /* Comp structure */
+        buffer_put_int(&b, comp->type);
+        buffer_put_int(&b, comp->enabled);
+        buffer_put_cstring(&b, comp->name);
+
+        len = buffer_len(&b);
+        buf = xmalloc(len);
+        memcpy(buf, buffer_ptr(&b), len);
+        memset(buffer_ptr(&b), 0, len);
+        buffer_free(&b);
+        if (lenp != NULL)
+                *lenp = len;
+        if (blobp != NULL)
+                *blobp = buf;
+        return len;
+}
+
+void
+mm_send_keystate(int socket)
+{
+        Buffer m;
+        u_char *blob, *p;
+        u_int bloblen, plen;
+
+        debug3("%s: Sending new keys: %p %p",
+            __FUNCTION__, newkeys[MODE_OUT], newkeys[MODE_IN]);
+
+        buffer_init(&m);
+
+        /* Keys from Kex */
+        if (!mm_newkeys_to_blob(MODE_OUT, &blob, &bloblen))
+                fatal("%s: conversion of newkeys failed", __FUNCTION__);
+
+        buffer_put_string(&m, blob, bloblen);
+        xfree(blob);
+
+        if (!mm_newkeys_to_blob(MODE_IN, &blob, &bloblen))
+                fatal("%s: conversion of newkeys failed", __FUNCTION__);
+
+        buffer_put_string(&m, blob, bloblen);
+        xfree(blob);
+
+        buffer_put_int(&m, packet_get_seqnr(MODE_OUT));
+        buffer_put_int(&m, packet_get_seqnr(MODE_IN));
+
+        debug3("%s: New keys have been sent", __FUNCTION__);
+
+        /* More key context */
+        plen = packet_get_keycontext(MODE_OUT, NULL);
+        p = xmalloc(plen+1);
+        packet_get_keycontext(MODE_OUT, p);
+        buffer_put_string(&m, p, plen);
+        xfree(p);
+
+        plen = packet_get_keycontext(MODE_IN, NULL);
+        p = xmalloc(plen+1);
+        packet_get_keycontext(MODE_IN, p);
+        buffer_put_string(&m, p, plen);
+        xfree(p);
+
+        /* Compression state */
+        debug3("%s: Sending compression state", __FUNCTION__);
+        buffer_put_string(&m, &outgoing_stream, sizeof(outgoing_stream));
+        buffer_put_string(&m, &incoming_stream, sizeof(incoming_stream));
+
+        mm_request_send(socket, MONITOR_REQ_KEYEXPORT, &m);
+        debug3("%s: Finished sending state", __FUNCTION__);
+
+        buffer_free(&m);
+}
+
+int
+mm_pty_allocown(int socket, int *ptyfd, int *ttyfd,
+    char *namebuf, int namebuflen)
+{
+        Buffer m;
+        u_char *p;
+        int success = 0;
+
+        buffer_init(&m);
+        mm_request_send(socket, MONITOR_REQ_PTY, &m);
+
+        debug3("%s: waiting for MONITOR_ANS_PTY", __FUNCTION__);
+        mm_request_receive_expect(socket, MONITOR_ANS_PTY, &m);
+
+        success = buffer_get_int(&m);
+        if (success == 0) {
+                debug3("%s: pty alloc failed", __FUNCTION__);
+                buffer_free(&m);
+                return (0);
+        }
+        p = buffer_get_string(&m, NULL);
+        buffer_free(&m);
+
+        strlcpy(namebuf, p, namebuflen); /* Possible truncation */
+        xfree(p);
+
+        *ptyfd = mm_receive_fd(socket);
+        *ttyfd = mm_receive_fd(socket);
+
+        /* Success */
+        return (1);
+}
+
+/* Request process termination */
+
+void
+mm_terminate(int socket)
+{
+        Buffer m;
+
+        buffer_init(&m);
+        mm_request_send(socket, MONITOR_REQ_TERM, &m);
+        buffer_free(&m);
+}
diff --git a/monitor_wrap.h b/monitor_wrap.h
new file mode 100644
index 000000000..3c8378024
--- /dev/null
+++ b/monitor_wrap.h
@@ -0,0 +1,99 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MM_WRAP_H_
+#define _MM_WRAP_H_
+#include "key.h"
+#include "buffer.h"
+
+struct mm_moduli {
+        int min;
+        int want;
+        int max;
+};
+
+enum mm_keytype {MM_HOSTKEY, MM_USERKEY};
+
+struct mm_keyallowed {
+        enum mm_keytype type;
+        char chost[MAXHOSTNAMELEN];
+        char cuser[MAXLOGNAME];
+};
+
+struct mm_master;
+
+struct passwd;
+DH *mm_choose_dh(int, int, int, int);
+DH *mm_read_moduli(int);
+int mm_key_sign(int, int, u_char **, u_int *, u_char *, u_int);
+void mm_inform_authserv(int, char *, char *);
+struct passwd *mm_getpwnamallow(int, const char *, int *);
+int mm_auth_password(int, char *);
+int mm_key_allowed(int, enum mm_keytype, char *, char *, Key *);
+#define mm_hostbased_key_allowed(x,u,h,z) \
+        mm_key_allowed(x, MM_HOSTKEY, u, h, z)
+#define mm_user_key_allowed(x,z) \
+        mm_key_allowed(x, MM_USERKEY, NULL, NULL, z)
+
+int mm_key_verify(int, enum mm_keytype, char *, char *,
+    Key *, u_char *, u_int, u_char *, u_int);
+
+void mm_terminate(int);
+
+/* Key export functions */
+struct Newkeys *mm_newkeys_from_blob(u_char *, int);
+int mm_newkeys_to_blob(int, u_char **, u_int *);
+
+void mm_apply_keystate(struct mm_master *);
+void mm_get_keystate(int);
+void mm_send_keystate(int);
+
+int mm_pty_allocown(int, int *, int *, char *, int);
+
+/* Functions on the montior that answer unprivileged requests */
+
+int mm_answer_moduli(int, Buffer *);
+int mm_answer_sign(int, Buffer *);
+int mm_answer_pwnamallow(int, Buffer *);
+int mm_answer_authserv(int, Buffer *);
+int mm_answer_authpassword(int, Buffer *);
+int mm_answer_keyallowed(int, Buffer *);
+int mm_answer_keyverify(int, Buffer *);
+int mm_answer_pty(int, Buffer *);
+int mm_answer_term(int, Buffer *);
+
+void mm_request_send(int , enum monitor_reqtype, Buffer *);
+void mm_request_receive(int, Buffer *);
+void mm_request_receive_expect(int, enum monitor_reqtype,
+    Buffer *);
+
+void *mm_zalloc(struct mm_master *, u_int, u_int);
+void mm_zfree(struct mm_master *, void *);
+void mm_init_compression(struct mm_master *);
+
+/* Utility functions */
+
+void pwfree(struct passwd *);
+#endif /* _MM_H_ */
diff --git a/packet.c b/packet.c
index 045d5a105..1c80af128 100644
--- a/packet.c
+++ b/packet.c
@@ -115,6 +115,8 @@ static int interactive_mode = 0;
 
 /* Session key information for Encryption and MAC */
 Newkeys *newkeys[MODE_MAX];
+static u_int32_t read_seqnr = 0;
+static u_int32_t send_seqnr = 0;
 
 /* roundup current message to extra_pad bytes */
 static u_char extra_pad = 0;
@@ -171,6 +173,87 @@ packet_connection_is_on_socket(void)
         return 1;
 }
 
+/* 
+ * Exports an IV from the CipherContext required to export the key
+ * state back from the unprivileged child to the privileged parent
+ * process.
+ */
+
+void
+packet_get_keyiv(int mode, u_char *iv, u_int len)
+{
+        CipherContext *cc;
+
+        if (mode == MODE_OUT)
+                cc = &send_context;
+        else
+                cc = &receive_context;
+
+        cipher_get_keyiv(cc, iv, len);
+}
+
+int
+packet_get_keycontext(int mode, u_char *dat)
+{
+        int plen;
+        CipherContext *cc;
+        
+        if (mode == MODE_OUT)
+                cc = &send_context;
+        else
+                cc = &receive_context;
+
+#if OPENSSL_VERSION_NUMBER < 0x00907000L
+        plen = sizeof(cc->evp.c);
+#else
+        plen = cc->evp.cipher->ctx_size;
+#endif
+
+        if (dat == NULL)
+                return (plen);
+
+#if OPENSSL_VERSION_NUMBER < 0x00907000L
+        memcpy(dat, &cc->evp.c, sizeof(cc->evp.c));
+#else
+        memcpy(dat, &cc->evp.cipher_data, plen);
+#endif
+        return (plen);
+}
+
+void
+packet_set_keycontext(int mode, u_char *dat)
+{
+        CipherContext *cc;
+        
+        if (mode == MODE_OUT)
+                cc = &send_context;
+        else
+                cc = &receive_context;
+
+#if OPENSSL_VERSION_NUMBER < 0x00907000L
+        memcpy(&cc->evp.c, dat, sizeof(cc->evp.c));
+#else
+        memcpy(&cc->evp.cipher_data, dat, cc->evp.cipher->ctx_size);
+#endif
+}
+
+u_int32_t
+packet_get_seqnr(int mode)
+{
+        return (mode == MODE_IN ? read_seqnr : send_seqnr);
+}
+
+void
+packet_set_seqnr(int mode, u_int32_t seqnr)
+{
+        if (mode == MODE_IN)
+                read_seqnr = seqnr;
+        else if (mode == MODE_OUT)
+                send_seqnr = seqnr;
+        else
+                fatal("%s: bad mode %d", __FUNCTION__, mode);
+}
+
 /* returns 1 if connection is via ipv4 */
 
 int
@@ -433,7 +516,7 @@ packet_send1(void)
          */
 }
 
-static void
+void
 set_newkeys(int mode)
 {
         Enc *enc;
@@ -477,8 +560,9 @@ set_newkeys(int mode)
         DBG(debug("cipher_init_context: %d", mode));
         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
             enc->iv, enc->block_size, encrypt);
-        memset(enc->iv,  0, enc->block_size);
-        memset(enc->key, 0, enc->key_len);
+        /* Deleting the keys does not gain extra security */
+        /* memset(enc->iv,  0, enc->block_size);
+           memset(enc->key, 0, enc->key_len); */
         if (comp->type != 0 && comp->enabled == 0) {
                 packet_init_compression();
                 if (mode == MODE_OUT)
@@ -495,7 +579,6 @@ set_newkeys(int mode)
 static void
 packet_send2(void)
 {
-        static u_int32_t seqnr = 0;
         u_char type, *cp, *macbuf = NULL;
         u_char padlen, pad;
         u_int packet_length = 0;
@@ -576,10 +659,10 @@ packet_send2(void)
 
         /* compute MAC over seqnr and packet(length fields, payload, padding) */
         if (mac && mac->enabled) {
-                macbuf = mac_compute(mac, seqnr,
+                macbuf = mac_compute(mac, send_seqnr,
                     buffer_ptr(&outgoing_packet),
                     buffer_len(&outgoing_packet));
-                DBG(debug("done calc MAC out #%d", seqnr));
+                DBG(debug("done calc MAC out #%d", send_seqnr));
         }
         /* encrypt packet and append to output buffer. */
         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
@@ -593,7 +676,7 @@ packet_send2(void)
         buffer_dump(&output);
 #endif
         /* increment sequence number for outgoing packets */
-        if (++seqnr == 0)
+        if (++send_seqnr == 0)
                 log("outgoing seqnr wraps around");
         buffer_clear(&outgoing_packet);
 
@@ -783,7 +866,6 @@ packet_read_poll1(void)
 static int
 packet_read_poll2(u_int32_t *seqnr_p)
 {
-        static u_int32_t seqnr = 0;
         static u_int packet_length = 0;
         u_int padlen, need;
         u_char *macbuf, *cp, type;
@@ -845,17 +927,17 @@ packet_read_poll2(u_int32_t *seqnr_p)
          * increment sequence number for incoming packet
          */
         if (mac && mac->enabled) {
-                macbuf = mac_compute(mac, seqnr,
+                macbuf = mac_compute(mac, read_seqnr,
                     buffer_ptr(&incoming_packet),
                     buffer_len(&incoming_packet));
                 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
                         packet_disconnect("Corrupted MAC on input.");
-                DBG(debug("MAC #%d ok", seqnr));
+                DBG(debug("MAC #%d ok", read_seqnr));
                 buffer_consume(&input, mac->mac_len);
         }
         if (seqnr_p != NULL)
-                *seqnr_p = seqnr;
-        if (++seqnr == 0)
+                *seqnr_p = read_seqnr;
+        if (++read_seqnr == 0)
                 log("incoming seqnr wraps around");
 
         /* get padlen */
diff --git a/packet.h b/packet.h
index d6bf2aab4..b87a03cf8 100644
--- a/packet.h
+++ b/packet.h
@@ -56,6 +56,13 @@ void	*packet_get_string(u_int *length_ptr);
 void     packet_disconnect(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 void     packet_send_debug(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 
+void     set_newkeys(int mode);
+void     packet_get_keyiv(int, u_char *, u_int);
+int      packet_get_keycontext(int, u_char *);
+void     packet_set_keycontext(int, u_char *);
+u_int32_t packet_get_seqnr(int);
+void     packet_set_seqnr(int, u_int32_t);
+
 void     packet_write_poll(void);
 void     packet_write_wait(void);
 int      packet_have_data_to_write(void);
diff --git a/servconf.c b/servconf.c
index 9bbd994ca..c3f1253e8 100644
--- a/servconf.c
+++ b/servconf.c
@@ -36,6 +36,8 @@ static void add_one_listen_addr(ServerOptions *, char *, u_short);
 
 /* AF_UNSPEC or AF_INET or AF_INET6 */
 extern int IPv4or6;
+/* Use of privilege separation or not */
+extern int use_privsep;
 
 /* Initializes the server options to their default values. */
 
@@ -110,6 +112,9 @@ initialize_server_options(ServerOptions *options)
         options->client_alive_count_max = -1;
         options->authorized_keys_file = NULL;
         options->authorized_keys_file2 = NULL;
+
+        /* Needs to be accessable in many places */
+        use_privsep = -1;
 }
 
 void
@@ -235,6 +240,10 @@ fill_default_server_options(ServerOptions *options)
         }
         if (options->authorized_keys_file == NULL)
                 options->authorized_keys_file = _PATH_SSH_USER_PERMITTED_KEYS;
+
+        /* Turn privilege separation on by default */
+        if (use_privsep == -1)
+                use_privsep = 1;
 }
 
 /* Keyword tokens. */
@@ -267,6 +276,7 @@ typedef enum {
         sBanner, sVerifyReverseMapping, sHostbasedAuthentication,
         sHostbasedUsesNameFromPacketOnly, sClientAliveInterval,
         sClientAliveCountMax, sAuthorizedKeysFile, sAuthorizedKeysFile2,
+        sUsePrivilegeSeparation,
         sDeprecated
 } ServerOpCodes;
 
@@ -342,6 +352,7 @@ static struct {
         { "clientalivecountmax", sClientAliveCountMax },
         { "authorizedkeysfile", sAuthorizedKeysFile },
         { "authorizedkeysfile2", sAuthorizedKeysFile2 },
+        { "useprivilegeseparation", sUsePrivilegeSeparation},
         { NULL, sBadOption }
 };
 
@@ -718,6 +729,10 @@ parse_flag:
                 intptr = &options->allow_tcp_forwarding;
                 goto parse_flag;
 
+        case sUsePrivilegeSeparation:
+                intptr = &use_privsep;
+                goto parse_flag;
+
         case sAllowUsers:
                 while ((arg = strdelim(&cp)) && *arg != '\0') {
                         if (options->num_allow_users >= MAX_ALLOW_USERS)
diff --git a/session.c b/session.c
index a31ff85d8..17227c9ff 100644
--- a/session.c
+++ b/session.c
@@ -56,6 +56,8 @@ RCSID("$OpenBSD: session.c,v 1.128 2002/02/16 00:51:44 markus Exp $");
 #include "serverloop.h"
 #include "canohost.h"
 #include "session.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
 
 #ifdef HAVE_CYGWIN
 #include <windows.h>
@@ -63,39 +65,15 @@ RCSID("$OpenBSD: session.c,v 1.128 2002/02/16 00:51:44 markus Exp $");
 #define is_winnt       (GetVersion() < 0x80000000)
 #endif
 
-/* types */
-
-#define TTYSZ 64
-typedef struct Session Session;
-struct Session {
-        int     used;
-        int     self;
-        struct passwd *pw;
-        Authctxt *authctxt;
-        pid_t   pid;
-        /* tty */
-        char    *term;
-        int     ptyfd, ttyfd, ptymaster;
-        int     row, col, xpixel, ypixel;
-        char    tty[TTYSZ];
-        /* X11 */
-        int     display_number;
-        char    *display;
-        int     screen;
-        char    *auth_display;
-        char    *auth_proto;
-        char    *auth_data;
-        int     single_connection;
-        /* proto 2 */
-        int     chanid;
-        int     is_subsystem;
-};
+/* Imports */
+extern int use_privsep;
+extern int mm_recvfd;
 
 /* func */
 
 Session *session_new(void);
 void    session_set_fds(Session *, int, int, int);
-static void     session_pty_cleanup(void *);
+void    session_pty_cleanup(void *);
 void    session_proctitle(Session *);
 int     session_setup_x11fwd(Session *);
 void    do_exec_pty(Session *, const char *);
@@ -112,7 +90,6 @@ int	check_quietlogin(Session *, const char *);
 static void do_authenticated1(Authctxt *);
 static void do_authenticated2(Authctxt *);
 
-static void session_close(Session *);
 static int session_pty_req(Session *);
 
 /* import */
@@ -1448,7 +1425,8 @@ session_pty_req(Session *s)
 {
         u_int len;
         int n_bytes;
-
+        int res;
+        
         if (no_pty_flag) {
                 debug("Allocating a pty not permitted for this authentication.");
                 return 0;
@@ -1477,7 +1455,15 @@ session_pty_req(Session *s)
 
         /* Allocate a pty and open it. */
         debug("Allocating pty.");
-        if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) {
+        if (!use_privsep) {
+                res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty,
+                        sizeof(s->tty));
+                if (res)
+                        pty_setowner(s->pw, s->tty);
+        } else 
+                res = mm_pty_allocown(mm_recvfd,
+                    &s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
+        if (!res) {
                 if (s->term)
                         xfree(s->term);
                 s->term = NULL;
@@ -1498,7 +1484,6 @@ session_pty_req(Session *s)
          * time in case we call fatal() (e.g., the connection gets closed).
          */
         fatal_add_cleanup(session_pty_cleanup, (void *)s);
-        pty_setowner(s->pw, s->tty);
 
         /* Set window size from the packet. */
         pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
@@ -1661,7 +1646,7 @@ session_set_fds(Session *s, int fdin, int fdout, int fderr)
  * Function to perform pty cleanup. Also called if we get aborted abnormally
  * (e.g., due to a dropped connection).
  */
-static void
+void
 session_pty_cleanup(void *session)
 {
         Session *s = session;
@@ -1739,7 +1724,7 @@ session_exit_message(Session *s, int status)
         s->chanid = -1;
 }
 
-static void
+void
 session_close(Session *s)
 {
         debug("session_close: session %d pid %d", s->self, s->pid);
diff --git a/session.h b/session.h
index ec8284a5f..e3123beed 100644
--- a/session.h
+++ b/session.h
@@ -26,6 +26,32 @@
 #ifndef SESSION_H
 #define SESSION_H
 
+#define TTYSZ 64
+typedef struct Session Session;
+struct Session {
+        int     used;
+        int     self;
+        struct passwd *pw;
+        Authctxt *authctxt;
+        pid_t   pid;
+        /* tty */
+        char    *term;
+        int     ptyfd, ttyfd, ptymaster;
+        int     row, col, xpixel, ypixel;
+        char    tty[TTYSZ];
+        /* X11 */
+        int     display_number;
+        char    *display;
+        int     screen;
+        char    *auth_display;
+        char    *auth_proto;
+        char    *auth_data;
+        int     single_connection;
+        /* proto 2 */
+        int     chanid;
+        int     is_subsystem;
+};
+
 void     do_authenticated(Authctxt *);
 
 int      session_open(Authctxt*, int);
@@ -34,4 +60,6 @@ void	 session_close_by_pid(pid_t, int);
 void     session_close_by_channel(int, void *);
 void     session_destroy_all(void);
 
+Session *session_new(void);
+void     session_close(Session *);
 #endif
diff --git a/sshd.c b/sshd.c
index ea9293251..cbe316087 100644
--- a/sshd.c
+++ b/sshd.c
@@ -72,6 +72,11 @@ RCSID("$OpenBSD: sshd.c,v 1.228 2002/02/27 21:23:13 stevesk Exp $");
 #include "misc.h"
 #include "dispatch.h"
 #include "channels.h"
+#include "session.h"
+#include "monitor_mm.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
+#include "monitor_fdpass.h"
 
 #ifdef LIBWRAP
 #include <tcpd.h>
@@ -189,8 +194,20 @@ u_int utmp_len = MAXHOSTNAMELEN;
 int *startup_pipes = NULL;
 int startup_pipe;               /* in child */
 
+/* variables used for privilege separation */
+#define MM_MEMSIZE      65536
+struct mm_master *mm_zback;
+struct mm_master *mm_zlib;
+
+extern int use_privsep;
+/* Socket for the child to receive a fd */
+extern int mm_recvfd;
+/* Socket for the parent to send a fd */
+int mm_sendfd;
+
 /* Prototypes for various functions defined later in this file. */
 void destroy_sensitive_data(void);
+void demote_sensitive_data(void);
 
 static void do_ssh1_kex(void);
 static void do_ssh2_kex(void);
@@ -477,6 +494,69 @@ destroy_sensitive_data(void)
         memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
 }
 
+/* Demote private to public keys for network child */
+void
+demote_sensitive_data(void)
+{
+        Key *tmp;
+        int i;
+
+        if (sensitive_data.server_key) {
+                tmp = key_demote(sensitive_data.server_key);
+                key_free(sensitive_data.server_key);
+                sensitive_data.server_key = tmp;
+        }
+        for (i = 0; i < options.num_host_key_files; i++) {
+                if (sensitive_data.host_keys[i]) {
+                        tmp = key_demote(sensitive_data.host_keys[i]);
+                        key_free(sensitive_data.host_keys[i]);
+                        sensitive_data.host_keys[i] = tmp;
+                }
+        }
+
+        /* We do not clear ssh1_host key and cookie.  XXX - Okay Niels? */
+}
+
+void
+privsep_postauth(Authctxt *authctxt)
+{
+        pid_t pid;
+
+        if (0) {
+                /* File descriptor passing is broken */
+                mm_apply_keystate(mm_zlib);
+                use_privsep = 0;
+                return;
+        }
+
+        pid = fork();
+        if (pid == -1)
+                fatal("fork of unprivileged child failed");
+        else if (pid != 0) {
+                debug2("User child is on pid %d", pid);
+                close(mm_recvfd);
+                monitor_child_postauth(mm_sendfd);
+
+                /* Teardown? */
+                exit(0);
+        }
+
+        close(mm_sendfd);
+
+        /* Demote the private keys to public keys. */
+        demote_sensitive_data();
+
+        /* Drop privileges */
+        if (seteuid(authctxt->pw->pw_uid) == -1)
+                fatal("%s: seteuid", __FUNCTION__);
+        if (setuid(authctxt->pw->pw_uid) == -1)
+                fatal("%s: setuid", __FUNCTION__);
+
+        /* It is safe now to apply the key state */
+        mm_apply_keystate(mm_zlib);
+}
+
+
 static char *
 list_hostkey_types(void)
 {
@@ -518,6 +598,25 @@ get_hostkey_by_type(int type)
         return NULL;
 }
 
+Key *
+get_hostkey_by_index(int ind)
+{
+        if (ind < 0 || ind >= options.num_host_key_files)
+                return (NULL);
+        return (sensitive_data.host_keys[ind]);
+}
+
+int
+get_hostkey_index(Key *key)
+{
+        int i;
+        for (i = 0; i < options.num_host_key_files; i++) {
+                if (key == sensitive_data.host_keys[i])
+                        return (i);
+        }
+        return (-1);
+}
+
 /*
  * returns 1 if connection should be dropped, 0 otherwise.
  * dropping starts at connection #max_startups_begin with a probability
@@ -594,6 +693,8 @@ main(int ac, char **av)
         int listen_sock, maxfd;
         int startup_p[2];
         int startups = 0;
+        Authctxt *authctxt;
+        int sp[2];
         Key *key;
         int ret, key_used = 0;
 
@@ -1231,23 +1332,84 @@ main(int ac, char **av)
 
         packet_set_nonblocking();
 
+        if (!use_privsep)
+                goto skip_privilegeseparation;
+                
+        /* Set up unprivileged child process to deal with network data */
+        monitor_socketpair(sp);
+        mm_recvfd = sp[0];
+        mm_sendfd = sp[1];
+
+        /* Used to share zlib space across processes */
+        mm_zback = mm_create(NULL, MM_MEMSIZE);
+        mm_zlib = mm_create(mm_zback, 20 * MM_MEMSIZE);
+
+        /* Compression needs to share state across borders */
+        mm_init_compression(mm_zlib);
+
+        pid = fork();
+        if (pid == -1)
+                fatal("fork of unprivileged child failed");
+        else if (pid != 0) {
+                debug2("Network child is on pid %d", pid);
+                authctxt = monitor_child_preauth(mm_sendfd);
+
+                /* The member allocation is not visible, so sync it */
+                mm_share_sync(&mm_zlib, &mm_zback);
+                goto authenticated;
+        } else {
+                /* Demote the private keys to public keys. */
+                demote_sensitive_data();
+
+                /* Change our root directory - /var/empty is standard*/
+                if (chroot("/var/empty") == -1)
+                        fatal("chroot(/var/empty)");
+                if (chdir("/") == -1)
+                        fatal("chdir(/)");
+                
+                /* Drop our privileges */
+                seteuid(32767); /* XXX - Niels */
+                setuid(32767);
+        }               
+
+ skip_privilegeseparation:
+
         /* perform the key exchange */
         /* authenticate user and start session */
         if (compat20) {
                 do_ssh2_kex();
-                do_authentication2();
+                authctxt = do_authentication2();
+                if (use_privsep)
+                        mm_send_keystate(mm_recvfd);
         } else {
                 do_ssh1_kex();
-                do_authentication();
+                authctxt = do_authentication();
         }
-        /* The connection has been terminated. */
-        verbose("Closing connection to %.100s", remote_ip);
+
+        /* If we use privilege separation, the unprivileged child exits */
+        if (use_privsep)
+                exit(0);
+
+ authenticated:
+        /* 
+         * In privilege separation, we fork another child and prepare
+         * file descriptor passing.
+         */
+        if (use_privsep)
+                privsep_postauth(authctxt);
+
+        /* Perform session preparation. */
+        do_authenticated(authctxt);
 
 #ifdef USE_PAM
         finish_pam();
 #endif /* USE_PAM */
 
         packet_close();
+
+        if (use_privsep)
+                mm_terminate(mm_recvfd);
+
         exit(0);
 }
 
@@ -1453,8 +1615,6 @@ do_ssh1_kex(void)
                 for (i = 0; i < 16; i++)
                         session_id[i] = session_key[i] ^ session_key[i + 16];
         }
-        /* Destroy the private and public keys.  They will no longer be needed. */
-        destroy_sensitive_data();
 
         /* Destroy the decrypted integer.  It is no longer needed. */
         BN_clear_free(session_key_int);
@@ -1502,6 +1662,7 @@ do_ssh2_kex(void)
         kex->client_version_string=client_version_string;
         kex->server_version_string=server_version_string;
         kex->load_host_key=&get_hostkey_by_type;
+        kex->host_key_index=&get_hostkey_index;
 
         xxx_kex = kex;