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authorColin Watson <cjwatson@debian.org>2005-05-30 21:44:32 +0000
committerColin Watson <cjwatson@debian.org>2005-05-30 21:44:32 +0000
commita55bd782aa819b7f5ae716de000f19f4f531850e (patch)
tree12638b19bc0ed9c8d48541d460693ab0fbb58e89 /sshd.0
parentfe9489f7e522f780f3fa5c2f28208124d193398c (diff)
parent5d05471f6657646d1d6500c7c43134462c407ee6 (diff)
Import OpenSSH 4.1p1.
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1SSHD(8) OpenBSD System Manager's Manual SSHD(8)
2
3NAME
4 sshd - OpenSSH SSH daemon
5
6SYNOPSIS
7 sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]
8 [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]
9
10DESCRIPTION
11 sshd (SSH Daemon) is the daemon program for ssh(1). Together these pro-
12 grams replace rlogin and rsh, and provide secure encrypted communications
13 between two untrusted hosts over an insecure network. The programs are
14 intended to be as easy to install and use as possible.
15
16 sshd is the daemon that listens for connections from clients. It is nor-
17 mally started at boot from /etc/rc. It forks a new daemon for each in-
18 coming connection. The forked daemons handle key exchange, encryption,
19 authentication, command execution, and data exchange. This implementa-
20 tion of sshd supports both SSH protocol version 1 and 2 simultaneously.
21 sshd works as follows:
22
23 SSH protocol version 1
24 Each host has a host-specific RSA key (normally 1024 bits) used to iden-
25 tify the host. Additionally, when the daemon starts, it generates a
26 server RSA key (normally 768 bits). This key is normally regenerated ev-
27 ery hour if it has been used, and is never stored on disk.
28
29 Whenever a client connects, the daemon responds with its public host and
30 server keys. The client compares the RSA host key against its own
31 database to verify that it has not changed. The client then generates a
32 256-bit random number. It encrypts this random number using both the
33 host key and the server key, and sends the encrypted number to the serv-
34 er. Both sides then use this random number as a session key which is
35 used to encrypt all further communications in the session. The rest of
36 the session is encrypted using a conventional cipher, currently Blowfish
37 or 3DES, with 3DES being used by default. The client selects the encryp-
38 tion algorithm to use from those offered by the server.
39
40 Next, the server and the client enter an authentication dialog. The
41 client tries to authenticate itself using .rhosts authentication combined
42 with RSA host authentication, RSA challenge-response authentication, or
43 password based authentication.
44
45 Regardless of the authentication type, the account is checked to ensure
46 that it is accessible. An account is not accessible if it is locked,
47 listed in DenyUsers or its group is listed in DenyGroups . The defini-
48 tion of a locked account is system dependant. Some platforms have their
49 own account database (eg AIX) and some modify the passwd field ( `*LK*'
50 on Solaris, `*' on HP-UX, containing `Nologin' on Tru64 and a leading
51 `!!' on Linux). If there is a requirement to disable password authenti-
52 cation for the account while allowing still public-key, then the passwd
53 field should be set to something other than these values (eg `NP' or
54 `*NP*' ).
55
56 rshd, rlogind, and rexecd are disabled (thus completely disabling rlogin
57 and rsh into the machine).
58
59 SSH protocol version 2
60 Version 2 works similarly: Each host has a host-specific key (RSA or DSA)
61 used to identify the host. However, when the daemon starts, it does not
62 generate a server key. Forward security is provided through a Diffie-
63 Hellman key agreement. This key agreement results in a shared session
64 key.
65
66 The rest of the session is encrypted using a symmetric cipher, currently
67 128-bit AES, Blowfish, 3DES, CAST128, Arcfour, 192-bit AES, or 256-bit
68 AES. The client selects the encryption algorithm to use from those of-
69 fered by the server. Additionally, session integrity is provided through
70 a cryptographic message authentication code (hmac-sha1 or hmac-md5).
71
72 Protocol version 2 provides a public key based user (PubkeyAuthentica-
73 tion) or client host (HostbasedAuthentication) authentication method,
74 conventional password authentication and challenge response based meth-
75 ods.
76
77 Command execution and data forwarding
78 If the client successfully authenticates itself, a dialog for preparing
79 the session is entered. At this time the client may request things like
80 allocating a pseudo-tty, forwarding X11 connections, forwarding TCP/IP
81 connections, or forwarding the authentication agent connection over the
82 secure channel.
83
84 Finally, the client either requests a shell or execution of a command.
85 The sides then enter session mode. In this mode, either side may send
86 data at any time, and such data is forwarded to/from the shell or command
87 on the server side, and the user terminal in the client side.
88
89 When the user program terminates and all forwarded X11 and other connec-
90 tions have been closed, the server sends command exit status to the
91 client, and both sides exit.
92
93 sshd can be configured using command-line options or a configuration file
94 (by default sshd_config(5)). Command-line options override values speci-
95 fied in the configuration file.
96
97 sshd rereads its configuration file when it receives a hangup signal,
98 SIGHUP, by executing itself with the name and options it was started
99 with, e.g., /usr/sbin/sshd.
100
101 The options are as follows:
102
103 -4 Forces sshd to use IPv4 addresses only.
104
105 -6 Forces sshd to use IPv6 addresses only.
106
107 -b bits
108 Specifies the number of bits in the ephemeral protocol version 1
109 server key (default 768).
110
111 -D When this option is specified, sshd will not detach and does not
112 become a daemon. This allows easy monitoring of sshd.
113
114 -d Debug mode. The server sends verbose debug output to the system
115 log, and does not put itself in the background. The server also
116 will not fork and will only process one connection. This option
117 is only intended for debugging for the server. Multiple -d op-
118 tions increase the debugging level. Maximum is 3.
119
120 -e When this option is specified, sshd will send the output to the
121 standard error instead of the system log.
122
123 -f configuration_file
124 Specifies the name of the configuration file. The default is
125 /etc/ssh/sshd_config. sshd refuses to start if there is no con-
126 figuration file.
127
128 -g login_grace_time
129 Gives the grace time for clients to authenticate themselves (de-
130 fault 120 seconds). If the client fails to authenticate the user
131 within this many seconds, the server disconnects and exits. A
132 value of zero indicates no limit.
133
134 -h host_key_file
135 Specifies a file from which a host key is read. This option must
136 be given if sshd is not run as root (as the normal host key files
137 are normally not readable by anyone but root). The default is
138 /etc/ssh/ssh_host_key for protocol version 1, and
139 /etc/ssh/ssh_host_rsa_key and /etc/ssh/ssh_host_dsa_key for pro-
140 tocol version 2. It is possible to have multiple host key files
141 for the different protocol versions and host key algorithms.
142
143 -i Specifies that sshd is being run from inetd(8). sshd is normally
144 not run from inetd because it needs to generate the server key
145 before it can respond to the client, and this may take tens of
146 seconds. Clients would have to wait too long if the key was re-
147 generated every time. However, with small key sizes (e.g., 512)
148 using sshd from inetd may be feasible.
149
150 -k key_gen_time
151 Specifies how often the ephemeral protocol version 1 server key
152 is regenerated (default 3600 seconds, or one hour). The motiva-
153 tion for regenerating the key fairly often is that the key is not
154 stored anywhere, and after about an hour it becomes impossible to
155 recover the key for decrypting intercepted communications even if
156 the machine is cracked into or physically seized. A value of ze-
157 ro indicates that the key will never be regenerated.
158
159 -o option
160 Can be used to give options in the format used in the configura-
161 tion file. This is useful for specifying options for which there
162 is no separate command-line flag. For full details of the op-
163 tions, and their values, see sshd_config(5).
164
165 -p port
166 Specifies the port on which the server listens for connections
167 (default 22). Multiple port options are permitted. Ports speci-
168 fied in the configuration file are ignored when a command-line
169 port is specified.
170
171 -q Quiet mode. Nothing is sent to the system log. Normally the be-
172 ginning, authentication, and termination of each connection is
173 logged.
174
175 -t Test mode. Only check the validity of the configuration file and
176 sanity of the keys. This is useful for updating sshd reliably as
177 configuration options may change.
178
179 -u len This option is used to specify the size of the field in the utmp
180 structure that holds the remote host name. If the resolved host
181 name is longer than len, the dotted decimal value will be used
182 instead. This allows hosts with very long host names that over-
183 flow this field to still be uniquely identified. Specifying -u0
184 indicates that only dotted decimal addresses should be put into
185 the utmp file. -u0 may also be used to prevent sshd from making
186 DNS requests unless the authentication mechanism or configuration
187 requires it. Authentication mechanisms that may require DNS in-
188 clude RhostsRSAAuthentication, HostbasedAuthentication and using
189 a from="pattern-list" option in a key file. Configuration op-
190 tions that require DNS include using a USER@HOST pattern in
191 AllowUsers or DenyUsers.
192
193CONFIGURATION FILE
194 sshd reads configuration data from /etc/ssh/sshd_config (or the file
195 specified with -f on the command line). The file format and configura-
196 tion options are described in sshd_config(5).
197
198LOGIN PROCESS
199 When a user successfully logs in, sshd does the following:
200
201 1. If the login is on a tty, and no command has been specified,
202 prints last login time and /etc/motd (unless prevented in the
203 configuration file or by $HOME/.hushlogin; see the FILES sec-
204 tion).
205
206 2. If the login is on a tty, records login time.
207
208 3. Checks /etc/nologin; if it exists, prints contents and quits
209 (unless root).
210
211 4. Changes to run with normal user privileges.
212
213 5. Sets up basic environment.
214
215 6. Reads the file $HOME/.ssh/environment, if it exists, and users
216 are allowed to change their environment. See the
217 PermitUserEnvironment option in sshd_config(5).
218
219 7. Changes to user's home directory.
220
221 8. If $HOME/.ssh/rc exists, runs it; else if /etc/ssh/sshrc ex-
222 ists, runs it; otherwise runs xauth. The ``rc'' files are
223 given the X11 authentication protocol and cookie in standard
224 input.
225
226 9. Runs user's shell or command.
227
228AUTHORIZED_KEYS FILE FORMAT
229 $HOME/.ssh/authorized_keys is the default file that lists the public keys
230 that are permitted for RSA authentication in protocol version 1 and for
231 public key authentication (PubkeyAuthentication) in protocol version 2.
232 AuthorizedKeysFile may be used to specify an alternative file.
233
234 Each line of the file contains one key (empty lines and lines starting
235 with a `#' are ignored as comments). Each RSA public key consists of the
236 following fields, separated by spaces: options, bits, exponent, modulus,
237 comment. Each protocol version 2 public key consists of: options, key-
238 type, base64 encoded key, comment. The options field is optional; its
239 presence is determined by whether the line starts with a number or not
240 (the options field never starts with a number). The bits, exponent, mod-
241 ulus and comment fields give the RSA key for protocol version 1; the com-
242 ment field is not used for anything (but may be convenient for the user
243 to identify the key). For protocol version 2 the keytype is ``ssh-dss''
244 or ``ssh-rsa''.
245
246 Note that lines in this file are usually several hundred bytes long (be-
247 cause of the size of the public key encoding) up to a limit of 8 kilo-
248 bytes, which permits DSA keys up to 8 kilobits and RSA keys up to 16
249 kilobits. You don't want to type them in; instead, copy the
250 identity.pub, id_dsa.pub or the id_rsa.pub file and edit it.
251
252 sshd enforces a minimum RSA key modulus size for protocol 1 and protocol
253 2 keys of 768 bits.
254
255 The options (if present) consist of comma-separated option specifica-
256 tions. No spaces are permitted, except within double quotes. The fol-
257 lowing option specifications are supported (note that option keywords are
258 case-insensitive):
259
260 from="pattern-list"
261 Specifies that in addition to public key authentication, the
262 canonical name of the remote host must be present in the comma-
263 separated list of patterns (`*' and `?' serve as wildcards). The
264 list may also contain patterns negated by prefixing them with
265 `!'; if the canonical host name matches a negated pattern, the
266 key is not accepted. The purpose of this option is to optionally
267 increase security: public key authentication by itself does not
268 trust the network or name servers or anything (but the key); how-
269 ever, if somebody somehow steals the key, the key permits an in-
270 truder to log in from anywhere in the world. This additional op-
271 tion makes using a stolen key more difficult (name servers and/or
272 routers would have to be compromised in addition to just the
273 key).
274
275 command="command"
276 Specifies that the command is executed whenever this key is used
277 for authentication. The command supplied by the user (if any) is
278 ignored. The command is run on a pty if the client requests a
279 pty; otherwise it is run without a tty. If an 8-bit clean chan-
280 nel is required, one must not request a pty or should specify no-
281 pty. A quote may be included in the command by quoting it with a
282 backslash. This option might be useful to restrict certain pub-
283 lic keys to perform just a specific operation. An example might
284 be a key that permits remote backups but nothing else. Note that
285 the client may specify TCP/IP and/or X11 forwarding unless they
286 are explicitly prohibited. Note that this option applies to
287 shell, command or subsystem execution.
288
289 environment="NAME=value"
290 Specifies that the string is to be added to the environment when
291 logging in using this key. Environment variables set this way
292 override other default environment values. Multiple options of
293 this type are permitted. Environment processing is disabled by
294 default and is controlled via the PermitUserEnvironment option.
295 This option is automatically disabled if UseLogin is enabled.
296
297 no-port-forwarding
298 Forbids TCP/IP forwarding when this key is used for authentica-
299 tion. Any port forward requests by the client will return an er-
300 ror. This might be used, e.g., in connection with the command
301 option.
302
303 no-X11-forwarding
304 Forbids X11 forwarding when this key is used for authentication.
305 Any X11 forward requests by the client will return an error.
306
307 no-agent-forwarding
308 Forbids authentication agent forwarding when this key is used for
309 authentication.
310
311 no-pty Prevents tty allocation (a request to allocate a pty will fail).
312
313 permitopen="host:port"
314 Limit local ``ssh -L'' port forwarding such that it may only con-
315 nect to the specified host and port. IPv6 addresses can be spec-
316 ified with an alternative syntax: host/port. Multiple permitopen
317 options may be applied separated by commas. No pattern matching
318 is performed on the specified hostnames, they must be literal do-
319 mains or addresses.
320
321 Examples
322 1024 33 12121...312314325 ylo@foo.bar
323
324 from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23...2334 ylo@niksula
325
326 command="dump /home",no-pty,no-port-forwarding 1024 33 23...2323 back-
327 up.hut.fi
328
329 permitopen="10.2.1.55:80",permitopen="10.2.1.56:25" 1024 33 23...2323
330
331SSH_KNOWN_HOSTS FILE FORMAT
332 The /etc/ssh/ssh_known_hosts and $HOME/.ssh/known_hosts files contain
333 host public keys for all known hosts. The global file should be prepared
334 by the administrator (optional), and the per-user file is maintained au-
335 tomatically: whenever the user connects from an unknown host its key is
336 added to the per-user file.
337
338 Each line in these files contains the following fields: hostnames, bits,
339 exponent, modulus, comment. The fields are separated by spaces.
340
341 Hostnames is a comma-separated list of patterns (`*' and `?' act as wild-
342 cards); each pattern in turn is matched against the canonical host name
343 (when authenticating a client) or against the user-supplied name (when
344 authenticating a server). A pattern may also be preceded by `!' to indi-
345 cate negation: if the host name matches a negated pattern, it is not ac-
346 cepted (by that line) even if it matched another pattern on the line.
347
348 Alternately, hostnames may be stored in a hashed form which hides host
349 names and addresses should the file's contents be disclosed. Hashed
350 hostnames start with a `|' character. Only one hashed hostname may ap-
351 pear on a single line and none of the above negation or wildcard opera-
352 tors may be applied.
353
354 Bits, exponent, and modulus are taken directly from the RSA host key;
355 they can be obtained, e.g., from /etc/ssh/ssh_host_key.pub. The optional
356 comment field continues to the end of the line, and is not used.
357
358 Lines starting with `#' and empty lines are ignored as comments.
359
360 When performing host authentication, authentication is accepted if any
361 matching line has the proper key. It is thus permissible (but not recom-
362 mended) to have several lines or different host keys for the same names.
363 This will inevitably happen when short forms of host names from different
364 domains are put in the file. It is possible that the files contain con-
365 flicting information; authentication is accepted if valid information can
366 be found from either file.
367
368 Note that the lines in these files are typically hundreds of characters
369 long, and you definitely don't want to type in the host keys by hand.
370 Rather, generate them by a script or by taking /etc/ssh/ssh_host_key.pub
371 and adding the host names at the front.
372
373 Examples
374
375 closenet,...,130.233.208.41 1024 37 159...93 closenet.hut.fi
376 cvs.openbsd.org,199.185.137.3 ssh-rsa AAAA1234.....=
377
378 # A hashed hostname
379 |1|JfKTdBh7rNbXkVAQCRp4OQoPfmI=|USECr3SWf1JUPsms5AqfD5QfxkM= ssh-rsa
380 AAAA1234.....=
381
382FILES
383 /etc/ssh/sshd_config
384 Contains configuration data for sshd. The file format and con-
385 figuration options are described in sshd_config(5).
386
387 /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key,
388 /etc/ssh/ssh_host_rsa_key
389 These three files contain the private parts of the host keys.
390 These files should only be owned by root, readable only by root,
391 and not accessible to others. Note that sshd does not start if
392 this file is group/world-accessible.
393
394 /etc/ssh/ssh_host_key.pub, /etc/ssh/ssh_host_dsa_key.pub,
395 /etc/ssh/ssh_host_rsa_key.pub
396 These three files contain the public parts of the host keys.
397 These files should be world-readable but writable only by root.
398 Their contents should match the respective private parts. These
399 files are not really used for anything; they are provided for the
400 convenience of the user so their contents can be copied to known
401 hosts files. These files are created using ssh-keygen(1).
402
403 /etc/moduli
404 Contains Diffie-Hellman groups used for the "Diffie-Hellman Group
405 Exchange". The file format is described in moduli(5).
406
407 /var/empty
408 chroot(2) directory used by sshd during privilege separation in
409 the pre-authentication phase. The directory should not contain
410 any files and must be owned by root and not group or world-
411 writable.
412
413 /var/run/sshd.pid
414 Contains the process ID of the sshd listening for connections (if
415 there are several daemons running concurrently for different
416 ports, this contains the process ID of the one started last).
417 The content of this file is not sensitive; it can be world-read-
418 able.
419
420 $HOME/.ssh/authorized_keys
421 Lists the public keys (RSA or DSA) that can be used to log into
422 the user's account. This file must be readable by root (which
423 may on some machines imply it being world-readable if the user's
424 home directory resides on an NFS volume). It is recommended that
425 it not be accessible by others. The format of this file is de-
426 scribed above. Users will place the contents of their
427 identity.pub, id_dsa.pub and/or id_rsa.pub files into this file,
428 as described in ssh-keygen(1).
429
430 /etc/ssh/ssh_known_hosts, $HOME/.ssh/known_hosts
431 These files are consulted when using rhosts with RSA host authen-
432 tication or protocol version 2 hostbased authentication to check
433 the public key of the host. The key must be listed in one of
434 these files to be accepted. The client uses the same files to
435 verify that it is connecting to the correct remote host. These
436 files should be writable only by root/the owner.
437 /etc/ssh/ssh_known_hosts should be world-readable, and
438 $HOME/.ssh/known_hosts can, but need not be, world-readable.
439
440 /etc/motd
441 See motd(5).
442
443 $HOME/.hushlogin
444 This file is used to suppress printing the last login time and
445 /etc/motd, if PrintLastLog and PrintMotd, respectively, are en-
446 abled. It does not suppress printing of the banner specified by
447 Banner.
448
449 /etc/nologin
450 If this file exists, sshd refuses to let anyone except root log
451 in. The contents of the file are displayed to anyone trying to
452 log in, and non-root connections are refused. The file should be
453 world-readable.
454
455 /etc/hosts.allow, /etc/hosts.deny
456 Access controls that should be enforced by tcp-wrappers are de-
457 fined here. Further details are described in hosts_access(5).
458
459 $HOME/.rhosts
460 This file is used during RhostsRSAAuthentication and
461 HostbasedAuthentication and contains host-username pairs, sepa-
462 rated by a space, one per line. The given user on the corre-
463 sponding host is permitted to log in without a password. The
464 same file is used by rlogind and rshd. The file must be writable
465 only by the user; it is recommended that it not be accessible by
466 others.
467
468 It is also possible to use netgroups in the file. Either host or
469 user name may be of the form +@groupname to specify all hosts or
470 all users in the group.
471
472 $HOME/.shosts
473 For ssh, this file is exactly the same as for .rhosts. However,
474 this file is not used by rlogin and rshd, so using this permits
475 access using SSH only.
476
477 /etc/hosts.equiv
478 This file is used during RhostsRSAAuthentication and
479 HostbasedAuthentication authentication. In the simplest form,
480 this file contains host names, one per line. Users on those
481 hosts are permitted to log in without a password, provided they
482 have the same user name on both machines. The host name may also
483 be followed by a user name; such users are permitted to log in as
484 any user on this machine (except root). Additionally, the syntax
485 ``+@group'' can be used to specify netgroups. Negated entries
486 start with `-'.
487
488 If the client host/user is successfully matched in this file, lo-
489 gin is automatically permitted provided the client and server us-
490 er names are the same. Additionally, successful client host key
491 authentication is required. This file must be writable only by
492 root; it is recommended that it be world-readable.
493
494 Warning: It is almost never a good idea to use user names in
495 hosts.equiv. Beware that it really means that the named user(s)
496 can log in as anybody, which includes bin, daemon, adm, and other
497 accounts that own critical binaries and directories. Using a us-
498 er name practically grants the user root access. The only valid
499 use for user names that I can think of is in negative entries.
500
501 Note that this warning also applies to rsh/rlogin.
502
503 /etc/shosts.equiv
504 This is processed exactly as /etc/hosts.equiv. However, this
505 file may be useful in environments that want to run both
506 rsh/rlogin and ssh.
507
508 $HOME/.ssh/environment
509 This file is read into the environment at login (if it exists).
510 It can only contain empty lines, comment lines (that start with
511 `#'), and assignment lines of the form name=value. The file
512 should be writable only by the user; it need not be readable by
513 anyone else. Environment processing is disabled by default and
514 is controlled via the PermitUserEnvironment option.
515
516 $HOME/.ssh/rc
517 If this file exists, it is run with /bin/sh after reading the en-
518 vironment files but before starting the user's shell or command.
519 It must not produce any output on stdout; stderr must be used in-
520 stead. If X11 forwarding is in use, it will receive the "proto
521 cookie" pair in its standard input (and DISPLAY in its environ-
522 ment). The script must call xauth(1) because sshd will not run
523 xauth automatically to add X11 cookies.
524
525 The primary purpose of this file is to run any initialization
526 routines which may be needed before the user's home directory be-
527 comes accessible; AFS is a particular example of such an environ-
528 ment.
529
530 This file will probably contain some initialization code followed
531 by something similar to:
532
533 if read proto cookie && [ -n "$DISPLAY" ]; then
534 if [ `echo $DISPLAY | cut -c1-10` = 'localhost:' ]; then
535 # X11UseLocalhost=yes
536 echo add unix:`echo $DISPLAY |
537 cut -c11-` $proto $cookie
538 else
539 # X11UseLocalhost=no
540 echo add $DISPLAY $proto $cookie
541 fi | xauth -q -
542 fi
543
544 If this file does not exist, /etc/ssh/sshrc is run, and if that
545 does not exist either, xauth is used to add the cookie.
546
547 This file should be writable only by the user, and need not be
548 readable by anyone else.
549
550 /etc/ssh/sshrc
551 Like $HOME/.ssh/rc. This can be used to specify machine-specific
552 login-time initializations globally. This file should be
553 writable only by root, and should be world-readable.
554
555SEE ALSO
556 scp(1), sftp(1), ssh(1), ssh-add(1), ssh-agent(1), ssh-keygen(1),
557 chroot(2), hosts_access(5), login.conf(5), moduli(5), sshd_config(5),
558 inetd(8), sftp-server(8)
559
560 T. Ylonen, T. Kivinen, M. Saarinen, T. Rinne, and S. Lehtinen, SSH
561 Protocol Architecture, draft-ietf-secsh-architecture-12.txt, January
562 2002, work in progress material.
563
564 M. Friedl, N. Provos, and W. A. Simpson, Diffie-Hellman Group Exchange
565 for the SSH Transport Layer Protocol, draft-ietf-secsh-dh-group-
566 exchange-02.txt, January 2002, work in progress material.
567
568AUTHORS
569 OpenSSH is a derivative of the original and free ssh 1.2.12 release by
570 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo
571 de Raadt and Dug Song removed many bugs, re-added newer features and
572 created OpenSSH. Markus Friedl contributed the support for SSH protocol
573 versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support
574 for privilege separation.
575
576OpenBSD 3.7 September 25, 1999 9