* New upstream release (closes: #395507, #397961, #420035). Important

  changes not previously backported to 4.3p2:
  - 4.4/4.4p1 (http://www.openssh.org/txt/release-4.4):
    + On portable OpenSSH, fix a GSSAPI authentication abort that could be
      used to determine the validity of usernames on some platforms.
    + Implemented conditional configuration in sshd_config(5) using the
      "Match" directive. This allows some configuration options to be
      selectively overridden if specific criteria (based on user, group,
      hostname and/or address) are met. So far a useful subset of
      post-authentication options are supported and more are expected to
      be added in future releases.
    + Add support for Diffie-Hellman group exchange key agreement with a
      final hash of SHA256.
    + Added a "ForceCommand" directive to sshd_config(5). Similar to the
      command="..." option accepted in ~/.ssh/authorized_keys, this forces
      the execution of the specified command regardless of what the user
      requested. This is very useful in conjunction with the new "Match"
      option.
    + Add a "PermitOpen" directive to sshd_config(5). This mirrors the
      permitopen="..." authorized_keys option, allowing fine-grained
      control over the port-forwardings that a user is allowed to
      establish.
    + Add optional logging of transactions to sftp-server(8).
    + ssh(1) will now record port numbers for hosts stored in
      ~/.ssh/known_hosts when a non-standard port has been requested
      (closes: #50612).
    + Add an "ExitOnForwardFailure" option to cause ssh(1) to exit (with a
      non-zero exit code) when requested port forwardings could not be
      established.
    + Extend sshd_config(5) "SubSystem" declarations to allow the
      specification of command-line arguments.
    + Replacement of all integer overflow susceptible invocations of
      malloc(3) and realloc(3) with overflow-checking equivalents.
    + Many manpage fixes and improvements.
    + Add optional support for OpenSSL hardware accelerators (engines),
      enabled using the --with-ssl-engine configure option.
    + Tokens in configuration files may be double-quoted in order to
      contain spaces (closes: #319639).
    + Move a debug() call out of a SIGCHLD handler, fixing a hang when the
      session exits very quickly (closes: #307890).
    + Fix some incorrect buffer allocation calculations (closes: #410599).
    + ssh-add doesn't ask for a passphrase if key file permissions are too
      liberal (closes: #103677).
    + Likewise, ssh doesn't ask either (closes: #99675).
  - 4.6/4.6p1 (http://www.openssh.org/txt/release-4.6):
    + sshd now allows the enabling and disabling of authentication methods
      on a per user, group, host and network basis via the Match directive
      in sshd_config.
    + Fixed an inconsistent check for a terminal when displaying scp
      progress meter (closes: #257524).
    + Fix "hang on exit" when background processes are running at the time
      of exit on a ttyful/login session (closes: #88337).
* Update to current GSSAPI patch from
  http://www.sxw.org.uk/computing/patches/openssh-4.6p1-gsskex-20070312.patch;
  install ChangeLog.gssapi.

1 files changed, 272 insertions, 284 deletions

diff --git a/sshd.8 b/sshd.8
index fec3c3582..74ea77182 100644
--- a/sshd.8
+++ b/sshd.8
@@ -34,7 +34,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd.8,v 1.215 2006/02/01 09:11:41 jmc Exp $
+.\" $OpenBSD: sshd.8,v 1.234 2006/08/21 08:15:57 dtucker Exp $
 .Dd September 25, 1999
 .Dt SSHD 8
 .Os
@@ -81,7 +81,7 @@ configuration file.
 .Nm
 rereads its configuration file when it receives a hangup signal,
 .Dv SIGHUP ,
-by executing itself with the name and options it was started with, e.g.,
+by executing itself with the name and options it was started with, e.g.\&
 .Pa /usr/sbin/sshd .
 .Pp
 The options are as follows:
@@ -154,7 +154,7 @@ is normally not run
 from inetd because it needs to generate the server key before it can
 respond to the client, and this may take tens of seconds.
 Clients would have to wait too long if the key was regenerated every time.
-However, with small key sizes (e.g., 512) using
+However, with small key sizes (e.g. 512) using
 .Nm
 from inetd may
 be feasible.
@@ -311,17 +311,6 @@ or
 .Ql \&*NP\&*
 ).
 .Pp
-System security is not improved unless
-.Nm rshd ,
-.Nm rlogind ,
-and
-.Nm rexecd
-are disabled (thus completely disabling
-.Xr rlogin
-and
-.Xr rsh
-into the machine).
-.Sh COMMAND EXECUTION AND DATA FORWARDING
 If the client successfully authenticates itself, a dialog for
 preparing the session is entered.
 At this time the client may request
@@ -329,7 +318,7 @@ things like allocating a pseudo-tty, forwarding X11 connections,
 forwarding TCP connections, or forwarding the authentication agent
 connection over the secure channel.
 .Pp
-Finally, the client either requests a shell or execution of a command.
+After this, the client either requests a shell or execution of a command.
 The sides then enter session mode.
 In this mode, either side may send
 data at any time, and such data is forwarded to/from the shell or
@@ -384,31 +373,73 @@ The
 .Dq rc
 files are given the X11
 authentication protocol and cookie in standard input.
+See
+.Sx SSHRC ,
+below.
 .It
 Runs user's shell or command.
 .El
+.Sh SSHRC
+If the file
+.Pa ~/.ssh/rc
+exists,
+.Xr sh 1
+runs it after reading the
+environment files but before starting the user's shell or command.
+It must not produce any output on stdout; stderr must be used
+instead.
+If X11 forwarding is in use, it will receive the "proto cookie" pair in
+its standard input (and
+.Ev DISPLAY
+in its environment).
+The script must call
+.Xr xauth 1
+because
+.Nm
+will not run xauth automatically to add X11 cookies.
+.Pp
+The primary purpose of this file is to run any initialization routines
+which may be needed before the user's home directory becomes
+accessible; AFS is a particular example of such an environment.
+.Pp
+This file will probably contain some initialization code followed by
+something similar to:
+.Bd -literal -offset 3n
+if read proto cookie && [ -n "$DISPLAY" ]; then
+        if [ `echo $DISPLAY | cut -c1-10` = 'localhost:' ]; then
+                # X11UseLocalhost=yes
+                echo add unix:`echo $DISPLAY |
+                    cut -c11-` $proto $cookie
+        else
+                # X11UseLocalhost=no
+                echo add $DISPLAY $proto $cookie
+        fi | xauth -q -
+fi
+.Ed
+.Pp
+If this file does not exist,
+.Pa /etc/ssh/sshrc
+is run, and if that
+does not exist either, xauth is used to add the cookie.
 .Sh AUTHORIZED_KEYS FILE FORMAT
-.Pa ~/.ssh/authorized_keys
-is the default file that lists the public keys that are
-permitted for RSA authentication in protocol version 1
-and for public key authentication (PubkeyAuthentication)
-in protocol version 2.
 .Cm AuthorizedKeysFile
-may be used to specify an alternative file.
-.Pp
+specifies the file containing public keys for
+public key authentication;
+if none is specified, the default is
+.Pa ~/.ssh/authorized_keys .
 Each line of the file contains one
 key (empty lines and lines starting with a
 .Ql #
 are ignored as
 comments).
-Each RSA public key consists of the following fields, separated by
-spaces: options, bits, exponent, modulus, comment.
-Each protocol version 2 public key consists of:
-options, keytype, base64 encoded key, comment.
-The options field
-is optional; its presence is determined by whether the line starts
+Protocol 1 public keys consist of the following space-separated fields:
+options, bits, exponent, modulus, comment.
+Protocol 2 public key consist of:
+options, keytype, base64-encoded key, comment.
+The options field is optional;
+its presence is determined by whether the line starts
 with a number or not (the options field never starts with a number).
-The bits, exponent, modulus and comment fields give the RSA key for
+The bits, exponent, modulus, and comment fields give the RSA key for
 protocol version 1; the
 comment field is not used for anything (but may be convenient for the
 user to identify the key).
@@ -423,7 +454,7 @@ Note that lines in this file are usually several hundred bytes long
 keys up to 16 kilobits.
 You don't want to type them in; instead, copy the
 .Pa identity.pub ,
-.Pa id_dsa.pub
+.Pa id_dsa.pub ,
 or the
 .Pa id_rsa.pub
 file and edit it.
@@ -438,26 +469,6 @@ No spaces are permitted, except within double quotes.
 The following option specifications are supported (note
 that option keywords are case-insensitive):
 .Bl -tag -width Ds
-.It Cm from="pattern-list"
-Specifies that in addition to public key authentication, the canonical name
-of the remote host must be present in the comma-separated list of
-patterns
-.Pf ( Ql \&*
-and
-.Ql \&?
-serve as wildcards).
-The list may also contain
-patterns negated by prefixing them with
-.Ql \&! ;
-if the canonical host name matches a negated pattern, the key is not accepted.
-The purpose
-of this option is to optionally increase security: public key authentication
-by itself does not trust the network or name servers or anything (but
-the key); however, if somebody somehow steals the key, the key
-permits an intruder to log in from anywhere in the world.
-This additional option makes using a stolen key more difficult (name
-servers and/or routers would have to be compromised in addition to
-just the key).
 .It Cm command="command"
 Specifies that the command is executed whenever this key is used for
 authentication.
@@ -473,6 +484,9 @@ to restrict certain public keys to perform just a specific operation.
 An example might be a key that permits remote backups but nothing else.
 Note that the client may specify TCP and/or X11
 forwarding unless they are explicitly prohibited.
+The command originally supplied by the client is available in the
+.Ev SSH_ORIGINAL_COMMAND
+environment variable.
 Note that this option applies to shell, command or subsystem execution.
 .It Cm environment="NAME=value"
 Specifies that the string is to be added to the environment when
@@ -487,20 +501,38 @@ option.
 This option is automatically disabled if
 .Cm UseLogin
 is enabled.
+.It Cm from="pattern-list"
+Specifies that in addition to public key authentication, the canonical name
+of the remote host must be present in the comma-separated list of
+patterns.
+The purpose
+of this option is to optionally increase security: public key authentication
+by itself does not trust the network or name servers or anything (but
+the key); however, if somebody somehow steals the key, the key
+permits an intruder to log in from anywhere in the world.
+This additional option makes using a stolen key more difficult (name
+servers and/or routers would have to be compromised in addition to
+just the key).
+.Pp
+See
+.Sx PATTERNS
+in
+.Xr ssh_config 5
+for more information on patterns.
+.It Cm no-agent-forwarding
+Forbids authentication agent forwarding when this key is used for
+authentication.
 .It Cm no-port-forwarding
 Forbids TCP forwarding when this key is used for authentication.
 Any port forward requests by the client will return an error.
-This might be used, e.g., in connection with the
+This might be used, e.g. in connection with the
 .Cm command
 option.
+.It Cm no-pty
+Prevents tty allocation (a request to allocate a pty will fail).
 .It Cm no-X11-forwarding
 Forbids X11 forwarding when this key is used for authentication.
 Any X11 forward requests by the client will return an error.
-.It Cm no-agent-forwarding
-Forbids authentication agent forwarding when this key is used for
-authentication.
-.It Cm no-pty
-Prevents tty allocation (a request to allocate a pty will fail).
 .It Cm permitopen="host:port"
 Limit local
 .Li ``ssh -L''
@@ -520,16 +552,20 @@ device on the server.
 Without this option, the next available device will be used if
 the client requests a tunnel.
 .El
-.Ss Examples
-1024 33 12121...312314325 ylo@foo.bar
 .Pp
-from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23...2334 ylo@niksula
-.Pp
-command="dump /home",no-pty,no-port-forwarding 1024 33 23...2323 backup.hut.fi
-.Pp
-permitopen="10.2.1.55:80",permitopen="10.2.1.56:25" 1024 33 23...2323
-.Pp
-tunnel="0",command="sh /etc/netstart tun0" ssh-rsa AAAA...== reyk@openbsd.org
+An example authorized_keys file:
+.Bd -literal -offset 3n
+# Comments allowed at start of line
+ssh-rsa AAAAB3Nza...LiPk== user@example.net
+from="*.sales.example.net,!pc.sales.example.net" ssh-rsa
+AAAAB2...19Q== john@example.net
+command="dump /home",no-pty,no-port-forwarding ssh-dss
+AAAAC3...51R== example.net
+permitopen="192.0.2.1:80",permitopen="192.0.2.2:25" ssh-dss
+AAAAB5...21S==
+tunnel="0",command="sh /etc/netstart tun0" ssh-rsa AAAA...==
+jane@example.net
+.Ed
 .Sh SSH_KNOWN_HOSTS FILE FORMAT
 The
 .Pa /etc/ssh/ssh_known_hosts
@@ -538,7 +574,7 @@ and
 files contain host public keys for all known hosts.
 The global file should
 be prepared by the administrator (optional), and the per-user file is
-maintained automatically: whenever the user connects from an unknown host
+maintained automatically: whenever the user connects from an unknown host,
 its key is added to the per-user file.
 .Pp
 Each line in these files contains the following fields: hostnames,
@@ -546,7 +582,7 @@ bits, exponent, modulus, comment.
 The fields are separated by spaces.
 .Pp
 Hostnames is a comma-separated list of patterns
-.Pf ( Ql \&*
+.Pf ( Ql *
 and
 .Ql \&?
 act as
@@ -558,6 +594,13 @@ A pattern may also be preceded by
 to indicate negation: if the host name matches a negated
 pattern, it is not accepted (by that line) even if it matched another
 pattern on the line.
+A hostname or address may optionally be enclosed within
+.Ql \&[
+and
+.Ql \&]
+brackets then followed by
+.Ql \&:
+and a non-standard port number.
 .Pp
 Alternately, hostnames may be stored in a hashed form which hides host names
 and addresses should the file's contents be disclosed.
@@ -568,7 +611,7 @@ Only one hashed hostname may appear on a single line and none of the above
 negation or wildcard operators may be applied.
 .Pp
 Bits, exponent, and modulus are taken directly from the RSA host key; they
-can be obtained, e.g., from
+can be obtained, for example, from
 .Pa /etc/ssh/ssh_host_key.pub .
 The optional comment field continues to the end of the line, and is not used.
 .Pp
@@ -593,88 +636,19 @@ Rather, generate them by a script
 or by taking
 .Pa /etc/ssh/ssh_host_key.pub
 and adding the host names at the front.
-.Ss Examples
-.Bd -literal
-closenet,...,130.233.208.41 1024 37 159...93 closenet.hut.fi
-cvs.openbsd.org,199.185.137.3 ssh-rsa AAAA1234.....=
-.Ed
-.Bd -literal
+.Pp
+An example ssh_known_hosts file:
+.Bd -literal -offset 3n
+# Comments allowed at start of line
+closenet,...,192.0.2.53 1024 37 159...93 closenet.example.net
+cvs.example.net,192.0.2.10 ssh-rsa AAAA1234.....=
 # A hashed hostname
 |1|JfKTdBh7rNbXkVAQCRp4OQoPfmI=|USECr3SWf1JUPsms5AqfD5QfxkM= ssh-rsa
 AAAA1234.....=
 .Ed
 .Sh FILES
-.Bl -tag -width Ds
-.It Pa /etc/ssh/sshd_config
-Contains configuration data for
-.Nm sshd .
-The file format and configuration options are described in
-.Xr sshd_config 5 .
-.It Pa /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_rsa_key
-These three files contain the private parts of the host keys.
-These files should only be owned by root, readable only by root, and not
-accessible to others.
-Note that
-.Nm
-does not start if this file is group/world-accessible.
-.It Pa /etc/ssh/ssh_host_key.pub, /etc/ssh/ssh_host_dsa_key.pub, /etc/ssh/ssh_host_rsa_key.pub
-These three files contain the public parts of the host keys.
-These files should be world-readable but writable only by
-root.
-Their contents should match the respective private parts.
-These files are not
-really used for anything; they are provided for the convenience of
-the user so their contents can be copied to known hosts files.
-These files are created using
-.Xr ssh-keygen 1 .
-.It Pa /etc/ssh/moduli
-Contains Diffie-Hellman groups used for the "Diffie-Hellman Group Exchange".
-The file format is described in
-.Xr moduli 5 .
-.It Pa /var/empty
-.Xr chroot 2
-directory used by
-.Nm
-during privilege separation in the pre-authentication phase.
-The directory should not contain any files and must be owned by root
-and not group or world-writable.
-.It Pa /var/run/sshd.pid
-Contains the process ID of the
-.Nm
-listening for connections (if there are several daemons running
-concurrently for different ports, this contains the process ID of the one
-started last).
-The content of this file is not sensitive; it can be world-readable.
-.It Pa ~/.ssh/authorized_keys
-Lists the public keys (RSA or DSA) that can be used to log into the user's account.
-This file must be readable by root (which may on some machines imply
-it being world-readable if the user's home directory resides on an NFS
-volume).
-It is recommended that it not be accessible by others.
-The format of this file is described above.
-Users will place the contents of their
-.Pa identity.pub ,
-.Pa id_dsa.pub
-and/or
-.Pa id_rsa.pub
-files into this file, as described in
-.Xr ssh-keygen 1 .
-.It Pa "/etc/ssh/ssh_known_hosts", "~/.ssh/known_hosts"
-These files are consulted when using rhosts with RSA host
-authentication or protocol version 2 hostbased authentication
-to check the public key of the host.
-The key must be listed in one of these files to be accepted.
-The client uses the same files
-to verify that it is connecting to the correct remote host.
-These files should be writable only by root/the owner.
-.Pa /etc/ssh/ssh_known_hosts
-should be world-readable, and
-.Pa ~/.ssh/known_hosts
-can, but need not be, world-readable.
-.It Pa /etc/motd
-See
-.Xr motd 5 .
-.It Pa ~/.hushlogin
+.Bl -tag -width Ds -compact
+.It ~/.hushlogin
 This file is used to suppress printing the last login time and
 .Pa /etc/motd ,
 if
@@ -685,86 +659,49 @@ respectively,
 are enabled.
 It does not suppress printing of the banner specified by
 .Cm Banner .
-.It Pa /etc/nologin
-If this file exists,
+.Pp
+.It ~/.rhosts
+This file is used for host-based authentication (see
+.Xr ssh 1
+for more information).
+On some machines this file may need to be
+world-readable if the user's home directory is on an NFS partition,
+because
 .Nm
-refuses to let anyone except root log in.
-The contents of the file
-are displayed to anyone trying to log in, and non-root connections are
-refused.
-The file should be world-readable.
-.It Pa /etc/hosts.allow, /etc/hosts.deny
-Access controls that should be enforced by tcp-wrappers are defined here.
-Further details are described in
-.Xr hosts_access 5 .
-.It Pa ~/.rhosts
-This file is used during
-.Cm RhostsRSAAuthentication
-and
-.Cm HostbasedAuthentication
-and contains host-username pairs, separated by a space, one per
-line.
-The given user on the corresponding host is permitted to log in
-without a password.
-The same file is used by rlogind and rshd.
-The file must
-be writable only by the user; it is recommended that it not be
+reads it as root.
+Additionally, this file must be owned by the user,
+and must not have write permissions for anyone else.
+The recommended
+permission for most machines is read/write for the user, and not
 accessible by others.
 .Pp
-It is also possible to use netgroups in the file.
-Either host or user
-name may be of the form +@groupname to specify all hosts or all users
-in the group.
-.It Pa ~/.shosts
-For ssh,
-this file is exactly the same as for
-.Pa .rhosts .
-However, this file is
-not used by rlogin and rshd, so using this permits access using SSH only.
-.It Pa /etc/hosts.equiv
-This file is used during
-.Cm RhostsRSAAuthentication
-and
-.Cm HostbasedAuthentication
-authentication.
-In the simplest form, this file contains host names, one per line.
-Users on
-those hosts are permitted to log in without a password, provided they
-have the same user name on both machines.
-The host name may also be
-followed by a user name; such users are permitted to log in as
-.Em any
-user on this machine (except root).
-Additionally, the syntax
-.Dq +@group
-can be used to specify netgroups.
-Negated entries start with
-.Ql \&- .
-.Pp
-If the client host/user is successfully matched in this file, login is
-automatically permitted provided the client and server user names are the
-same.
-Additionally, successful client host key authentication is required.
-This file must be writable only by root; it is recommended
-that it be world-readable.
-.Pp
-.Sy "Warning: It is almost never a good idea to use user names in"
-.Pa hosts.equiv .
-Beware that it really means that the named user(s) can log in as
-.Em anybody ,
-which includes bin, daemon, adm, and other accounts that own critical
-binaries and directories.
-Using a user name practically grants the user root access.
-The only valid use for user names that I can think
-of is in negative entries.
-.Pp
-Note that this warning also applies to rsh/rlogin.
-.It Pa /etc/shosts.equiv
-This is processed exactly as
-.Pa /etc/hosts.equiv .
-However, this file may be useful in environments that want to run both
-rsh/rlogin and ssh.
-.It Pa ~/.ssh/environment
+.It ~/.shosts
+This file is used in exactly the same way as
+.Pa .rhosts ,
+but allows host-based authentication without permitting login with
+rlogin/rsh.
+.Pp
+.It ~/.ssh/authorized_keys
+Lists the public keys (RSA/DSA) that can be used for logging in as this user.
+The format of this file is described above.
+The content of the file is not highly sensitive, but the recommended
+permissions are read/write for the user, and not accessible by others.
+.Pp
+If this file, the
+.Pa ~/.ssh
+directory, or the user's home directory are writable
+by other users, then the file could be modified or replaced by unauthorized
+users.
+In this case,
+.Nm
+will not allow it to be used unless the
+.Cm StrictModes
+option has been set to
+.Dq no .
+The recommended permissions can be set by executing
+.Dq chmod go-w ~/ ~/.ssh ~/.ssh/authorized_keys .
+.Pp
+.It ~/.ssh/environment
 This file is read into the environment at login (if it exists).
 It can only contain empty lines, comment lines (that start with
 .Ql # ) ,
@@ -775,55 +712,115 @@ Environment processing is disabled by default and is
 controlled via the
 .Cm PermitUserEnvironment
 option.
-.It Pa ~/.ssh/rc
-If this file exists, it is run with
-.Pa /bin/sh
-after reading the
-environment files but before starting the user's shell or command.
-It must not produce any output on stdout; stderr must be used
-instead.
-If X11 forwarding is in use, it will receive the "proto cookie" pair in
-its standard input (and
-.Ev DISPLAY
-in its environment).
-The script must call
-.Xr xauth 1
-because
+.Pp
+.It ~/.ssh/known_hosts
+Contains a list of host keys for all hosts the user has logged into
+that are not already in the systemwide list of known host keys.
+The format of this file is described above.
+This file should be writable only by root/the owner and
+can, but need not be, world-readable.
+.Pp
+.It ~/.ssh/rc
+Contains initialization routines to be run before
+the user's home directory becomes accessible.
+This file should be writable only by the user, and need not be
+readable by anyone else.
+.Pp
+.It /etc/hosts.allow
+.It /etc/hosts.deny
+Access controls that should be enforced by tcp-wrappers are defined here.
+Further details are described in
+.Xr hosts_access 5 .
+.Pp
+.It /etc/hosts.equiv
+This file is for host-based authentication (see
+.Xr ssh 1 ) .
+It should only be writable by root.
+.Pp
+.It /etc/ssh/moduli
+Contains Diffie-Hellman groups used for the "Diffie-Hellman Group Exchange".
+The file format is described in
+.Xr moduli 5 .
+.Pp
+.It /etc/motd
+See
+.Xr motd 5 .
+.Pp
+.It /etc/nologin
+If this file exists,
 .Nm
-will not run xauth automatically to add X11 cookies.
+refuses to let anyone except root log in.
+The contents of the file
+are displayed to anyone trying to log in, and non-root connections are
+refused.
+The file should be world-readable.
 .Pp
-The primary purpose of this file is to run any initialization routines
-which may be needed before the user's home directory becomes
-accessible; AFS is a particular example of such an environment.
+.It /etc/shosts.equiv
+This file is used in exactly the same way as
+.Pa hosts.equiv ,
+but allows host-based authentication without permitting login with
+rlogin/rsh.
+.Pp
+.It /etc/ssh/ssh_known_hosts
+Systemwide list of known host keys.
+This file should be prepared by the
+system administrator to contain the public host keys of all machines in the
+organization.
+The format of this file is described above.
+This file should be writable only by root/the owner and
+should be world-readable.
 .Pp
-This file will probably contain some initialization code followed by
-something similar to:
-.Bd -literal
-if read proto cookie && [ -n "$DISPLAY" ]; then
-        if [ `echo $DISPLAY | cut -c1-10` = 'localhost:' ]; then
-                # X11UseLocalhost=yes
-                echo add unix:`echo $DISPLAY |
-                    cut -c11-` $proto $cookie
-        else
-                # X11UseLocalhost=no
-                echo add $DISPLAY $proto $cookie
-        fi | xauth -q -
-fi
-.Ed
+.It /etc/ssh/ssh_host_key
+.It /etc/ssh/ssh_host_dsa_key
+.It /etc/ssh/ssh_host_rsa_key
+These three files contain the private parts of the host keys.
+These files should only be owned by root, readable only by root, and not
+accessible to others.
+Note that
+.Nm
+does not start if these files are group/world-accessible.
 .Pp
-If this file does not exist,
-.Pa /etc/ssh/sshrc
-is run, and if that
-does not exist either, xauth is used to add the cookie.
+.It /etc/ssh/ssh_host_key.pub
+.It /etc/ssh/ssh_host_dsa_key.pub
+.It /etc/ssh/ssh_host_rsa_key.pub
+These three files contain the public parts of the host keys.
+These files should be world-readable but writable only by
+root.
+Their contents should match the respective private parts.
+These files are not
+really used for anything; they are provided for the convenience of
+the user so their contents can be copied to known hosts files.
+These files are created using
+.Xr ssh-keygen 1 .
 .Pp
-This file should be writable only by the user, and need not be
-readable by anyone else.
-.It Pa /etc/ssh/sshrc
-Like
-.Pa ~/.ssh/rc .
-This can be used to specify
+.It /etc/ssh/sshd_config
+Contains configuration data for
+.Nm sshd .
+The file format and configuration options are described in
+.Xr sshd_config 5 .
+.Pp
+.It /etc/ssh/sshrc
+Similar to
+.Pa ~/.ssh/rc ,
+it can be used to specify
 machine-specific login-time initializations globally.
 This file should be writable only by root, and should be world-readable.
+.Pp
+.It /var/empty
+.Xr chroot 2
+directory used by
+.Nm
+during privilege separation in the pre-authentication phase.
+The directory should not contain any files and must be owned by root
+and not group or world-writable.
+.Pp
+.It /var/run/sshd.pid
+Contains the process ID of the
+.Nm
+listening for connections (if there are several daemons running
+concurrently for different ports, this contains the process ID of the one
+started last).
+The content of this file is not sensitive; it can be world-readable.
 .El
 .Sh SEE ALSO
 .Xr scp 1 ,
@@ -839,26 +836,6 @@ This file should be writable only by root, and should be world-readable.
 .Xr sshd_config 5 ,
 .Xr inetd 8 ,
 .Xr sftp-server 8
-.Rs
-.%A T. Ylonen
-.%A T. Kivinen
-.%A M. Saarinen
-.%A T. Rinne
-.%A S. Lehtinen
-.%T "SSH Protocol Architecture"
-.%N draft-ietf-secsh-architecture-12.txt
-.%D January 2002
-.%O work in progress material
-.Re
-.Rs
-.%A M. Friedl
-.%A N. Provos
-.%A W. A. Simpson
-.%T "Diffie-Hellman Group Exchange for the SSH Transport Layer Protocol"
-.%N draft-ietf-secsh-dh-group-exchange-02.txt
-.%D January 2002
-.%O work in progress material
-.Re
 .Sh AUTHORS
 OpenSSH is a derivative of the original and free
 ssh 1.2.12 release by Tatu Ylonen.
@@ -870,3 +847,14 @@ Markus Friedl contributed the support for SSH
 protocol versions 1.5 and 2.0.
 Niels Provos and Markus Friedl contributed support
 for privilege separation.
+.Sh CAVEATS
+System security is not improved unless
+.Nm rshd ,
+.Nm rlogind ,
+and
+.Nm rexecd
+are disabled (thus completely disabling
+.Xr rlogin
+and
+.Xr rsh
+into the machine).