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-rw-r--r--ssh.189
1 files changed, 53 insertions, 36 deletions
diff --git a/ssh.1 b/ssh.1
index eba0e0f93..548339e6b 100644
--- a/ssh.1
+++ b/ssh.1
@@ -9,7 +9,7 @@
9.\" 9.\"
10.\" Created: Sat Apr 22 21:55:14 1995 ylo 10.\" Created: Sat Apr 22 21:55:14 1995 ylo
11.\" 11.\"
12.\" $Id: ssh.1,v 1.20 2000/03/26 03:04:54 damien Exp $ 12.\" $Id: ssh.1,v 1.21 2000/04/13 02:26:37 damien Exp $
13.\" 13.\"
14.Dd September 25, 1999 14.Dd September 25, 1999
15.Dt SSH 1 15.Dt SSH 1
@@ -49,7 +49,7 @@
49.Oc 49.Oc
50.Op Ar hostname | user@hostname 50.Op Ar hostname | user@hostname
51.Op Ar command 51.Op Ar command
52.Sh DESCRIPTION 52.Sh DESCRIPTION
53.Nm 53.Nm
54(Secure Shell) is a program for logging into a remote machine and for 54(Secure Shell) is a program for logging into a remote machine and for
55executing commands on a remote machine. 55executing commands on a remote machine.
@@ -60,7 +60,7 @@ X11 connections and
60arbitrary TCP/IP ports can also be forwarded over the secure channel. 60arbitrary TCP/IP ports can also be forwarded over the secure channel.
61.Pp 61.Pp
62.Nm 62.Nm
63connects and logs into the specified 63connects and logs into the specified
64.Ar hostname . 64.Ar hostname .
65The user must prove 65The user must prove
66his/her identity to the remote machine using one of several methods. 66his/her identity to the remote machine using one of several methods.
@@ -71,7 +71,7 @@ or
71.Pa /etc/shosts.equiv 71.Pa /etc/shosts.equiv
72on the remote machine, and the user names are 72on the remote machine, and the user names are
73the same on both sides, the user is immediately permitted to log in. 73the same on both sides, the user is immediately permitted to log in.
74Second, if 74Second, if
75.Pa \&.rhosts 75.Pa \&.rhosts
76or 76or
77.Pa \&.shosts 77.Pa \&.shosts
@@ -94,7 +94,7 @@ It means that if the login would be permitted by
94or 94or
95.Pa /etc/shosts.equiv , 95.Pa /etc/shosts.equiv ,
96and if additionally the server can verify the client's 96and if additionally the server can verify the client's
97host key (see 97host key (see
98.Pa /etc/ssh_known_hosts 98.Pa /etc/ssh_known_hosts
99and 99and
100.Pa $HOME/.ssh/known_hosts 100.Pa $HOME/.ssh/known_hosts
@@ -109,17 +109,17 @@ spoofing, DNS spoofing and routing spoofing.
109and the rlogin/rsh protocol in general, are inherently insecure and should be 109and the rlogin/rsh protocol in general, are inherently insecure and should be
110disabled if security is desired.] 110disabled if security is desired.]
111.Pp 111.Pp
112As a third authentication method, 112As a third authentication method,
113.Nm 113.Nm
114supports RSA based authentication. 114supports RSA based authentication.
115The scheme is based on public-key cryptography: there are cryptosystems 115The scheme is based on public-key cryptography: there are cryptosystems
116where encryption and decryption are done using separate keys, and it 116where encryption and decryption are done using separate keys, and it
117is not possible to derive the decryption key from the encryption key. 117is not possible to derive the decryption key from the encryption key.
118RSA is one such system. 118RSA is one such system.
119The idea is that each user creates a public/private 119The idea is that each user creates a public/private
120key pair for authentication purposes. 120key pair for authentication purposes.
121The server knows the public key, and only the user knows the private key. 121The server knows the public key, and only the user knows the private key.
122The file 122The file
123.Pa $HOME/.ssh/authorized_keys 123.Pa $HOME/.ssh/authorized_keys
124lists the public keys that are permitted for logging 124lists the public keys that are permitted for logging
125in. 125in.
@@ -142,18 +142,18 @@ key but without disclosing it to the server.
142implements the RSA authentication protocol automatically. 142implements the RSA authentication protocol automatically.
143The user creates his/her RSA key pair by running 143The user creates his/her RSA key pair by running
144.Xr ssh-keygen 1 . 144.Xr ssh-keygen 1 .
145This stores the private key in 145This stores the private key in
146.Pa \&.ssh/identity 146.Pa \&.ssh/identity
147and the public key in 147and the public key in
148.Pa \&.ssh/identity.pub 148.Pa \&.ssh/identity.pub
149in the user's home directory. 149in the user's home directory.
150The user should then copy the 150The user should then copy the
151.Pa identity.pub 151.Pa identity.pub
152to 152to
153.Pa \&.ssh/authorized_keys 153.Pa \&.ssh/authorized_keys
154in his/her home directory on the remote machine (the 154in his/her home directory on the remote machine (the
155.Pa authorized_keys 155.Pa authorized_keys
156file corresponds to the conventional 156file corresponds to the conventional
157.Pa \&.rhosts 157.Pa \&.rhosts
158file, and has one key 158file, and has one key
159per line, though the lines can be very long). 159per line, though the lines can be very long).
@@ -167,7 +167,7 @@ See
167.Xr ssh-agent 1 167.Xr ssh-agent 1
168for more information. 168for more information.
169.Pp 169.Pp
170If other authentication methods fail, 170If other authentication methods fail,
171.Nm 171.Nm
172prompts the user for a password. 172prompts the user for a password.
173The password is sent to the remote 173The password is sent to the remote
@@ -188,7 +188,7 @@ and suspend
188with 188with
189.Ic ~^Z . 189.Ic ~^Z .
190All forwarded connections can be listed with 190All forwarded connections can be listed with
191.Ic ~# 191.Ic ~#
192and if 192and if
193the session blocks waiting for forwarded X11 or TCP/IP 193the session blocks waiting for forwarded X11 or TCP/IP
194connections to terminate, it can be backgrounded with 194connections to terminate, it can be backgrounded with
@@ -232,7 +232,7 @@ Forwarding of X11 connections can be
232configured on the command line or in configuration files. 232configured on the command line or in configuration files.
233.Pp 233.Pp
234The 234The
235.Ev DISPLAY 235.Ev DISPLAY
236value set by 236value set by
237.Nm 237.Nm
238will point to the server machine, but with a display number greater 238will point to the server machine, but with a display number greater
@@ -265,10 +265,10 @@ electronic purse; another is going trough firewalls.
265.Nm 265.Nm
266automatically maintains and checks a database containing RSA-based 266automatically maintains and checks a database containing RSA-based
267identifications for all hosts it has ever been used with. 267identifications for all hosts it has ever been used with.
268The database is stored in 268The database is stored in
269.Pa \&.ssh/known_hosts 269.Pa \&.ssh/known_hosts
270in the user's home directory. 270in the user's home directory.
271Additionally, the file 271Additionally, the file
272.Pa /etc/ssh_known_hosts 272.Pa /etc/ssh_known_hosts
273is automatically checked for known hosts. 273is automatically checked for known hosts.
274Any new hosts are automatically added to the user's file. 274Any new hosts are automatically added to the user's file.
@@ -290,10 +290,10 @@ host key is not known or has changed.
290Disables forwarding of the authentication agent connection. 290Disables forwarding of the authentication agent connection.
291This may also be specified on a per-host basis in the configuration file. 291This may also be specified on a per-host basis in the configuration file.
292.It Fl c Ar blowfish|3des 292.It Fl c Ar blowfish|3des
293Selects the cipher to use for encrypting the session. 293Selects the cipher to use for encrypting the session.
294.Ar 3des 294.Ar 3des
295is used by default. 295is used by default.
296It is believed to be secure. 296It is believed to be secure.
297.Ar 3des 297.Ar 3des
298(triple-des) is an encrypt-decrypt-encrypt triple with three different keys. 298(triple-des) is an encrypt-decrypt-encrypt triple with three different keys.
299It is presumably more secure than the 299It is presumably more secure than the
@@ -322,7 +322,7 @@ This is useful if
322.Nm 322.Nm
323is going to ask for passwords or passphrases, but the user 323is going to ask for passwords or passphrases, but the user
324wants it in the background. 324wants it in the background.
325This implies 325This implies
326.Fl n . 326.Fl n .
327The recommended way to start X11 programs at a remote site is with 327The recommended way to start X11 programs at a remote site is with
328something like 328something like
@@ -330,9 +330,9 @@ something like
330.It Fl g 330.It Fl g
331Allows remote hosts to connect to local forwarded ports. 331Allows remote hosts to connect to local forwarded ports.
332.It Fl i Ar identity_file 332.It Fl i Ar identity_file
333Selects the file from which the identity (private key) for 333Selects the file from which the identity (private key) for
334RSA authentication is read. 334RSA authentication is read.
335Default is 335Default is
336.Pa \&.ssh/identity 336.Pa \&.ssh/identity
337in the user's home directory. 337in the user's home directory.
338Identity files may also be specified on 338Identity files may also be specified on
@@ -548,6 +548,12 @@ and
548are supported. 548are supported.
549The default is 549The default is
550.Dq 3des . 550.Dq 3des .
551.It Cm Ciphers
552Specifies the ciphers allowed for protocol version 2
553in order of preference.
554Multiple ciphers must be comma-separated.
555The default is
556.Dq blowfish-cbc,3des-cbc,arcfour,cast128-cbc .
551.It Cm Compression 557.It Cm Compression
552Specifies whether to use compression. 558Specifies whether to use compression.
553The argument must be 559The argument must be
@@ -577,12 +583,12 @@ followed by a letter, or
577to disable the escape 583to disable the escape
578character entirely (making the connection transparent for binary 584character entirely (making the connection transparent for binary
579data). 585data).
580.It Cm FallBackToRsh 586.It Cm FallBackToRsh
581Specifies that if connecting via 587Specifies that if connecting via
582.Nm 588.Nm
583fails due to a connection refused error (there is no 589fails due to a connection refused error (there is no
584.Xr sshd 8 590.Xr sshd 8
585listening on the remote host), 591listening on the remote host),
586.Xr rsh 1 592.Xr rsh 1
587should automatically be used instead (after a suitable warning about 593should automatically be used instead (after a suitable warning about
588the session being unencrypted). 594the session being unencrypted).
@@ -599,10 +605,10 @@ or
599.Dq no . 605.Dq no .
600.It Cm ForwardX11 606.It Cm ForwardX11
601Specifies whether X11 connections will be automatically redirected 607Specifies whether X11 connections will be automatically redirected
602over the secure channel and 608over the secure channel and
603.Ev DISPLAY 609.Ev DISPLAY
604set. 610set.
605The argument must be 611The argument must be
606.Dq yes 612.Dq yes
607or 613or
608.Dq no . 614.Dq no .
@@ -618,7 +624,7 @@ or
618The default is 624The default is
619.Dq no . 625.Dq no .
620.It Cm GlobalKnownHostsFile 626.It Cm GlobalKnownHostsFile
621Specifies a file to use instead of 627Specifies a file to use instead of
622.Pa /etc/ssh_known_hosts . 628.Pa /etc/ssh_known_hosts .
623.It Cm HostName 629.It Cm HostName
624Specifies the real host name to log into. 630Specifies the real host name to log into.
@@ -697,6 +703,17 @@ or
697.It Cm Port 703.It Cm Port
698Specifies the port number to connect on the remote host. 704Specifies the port number to connect on the remote host.
699Default is 22. 705Default is 22.
706.It Cm Protocol
707Specifies the protocol versions
708.Nm
709should support in order of preference.
710The possible values are
711.Dq 1
712and
713.Dq 2 .
714Multiple versions must be comma-separated.
715The default is
716.Dq 1 .
700.It Cm ProxyCommand 717.It Cm ProxyCommand
701Specifies the command to use to connect to the server. 718Specifies the command to use to connect to the server.
702The command 719The command
@@ -773,7 +790,7 @@ The default is
773.Dq no . 790.Dq no .
774.It Cm StrictHostKeyChecking 791.It Cm StrictHostKeyChecking
775If this flag is set to 792If this flag is set to
776.Dq yes , 793.Dq yes ,
777.Nm 794.Nm
778ssh will never automatically add host keys to the 795ssh will never automatically add host keys to the
779.Pa $HOME/.ssh/known_hosts 796.Pa $HOME/.ssh/known_hosts
@@ -839,7 +856,7 @@ will normally set the following environment variables:
839The 856The
840.Ev DISPLAY 857.Ev DISPLAY
841variable indicates the location of the X11 server. 858variable indicates the location of the X11 server.
842It is automatically set by 859It is automatically set by
843.Nm 860.Nm
844to point to a value of the form 861to point to a value of the form
845.Dq hostname:n 862.Dq hostname:n
@@ -885,10 +902,10 @@ on to new connections).
885Set to the name of the user logging in. 902Set to the name of the user logging in.
886.El 903.El
887.Pp 904.Pp
888Additionally, 905Additionally,
889.Nm 906.Nm
890reads 907reads
891.Pa $HOME/.ssh/environment , 908.Pa $HOME/.ssh/environment ,
892and adds lines of the format 909and adds lines of the format
893.Dq VARNAME=value 910.Dq VARNAME=value
894to the environment. 911to the environment.
@@ -911,7 +928,7 @@ ignores this file if it is accessible by others.
911It is possible to specify a passphrase when 928It is possible to specify a passphrase when
912generating the key; the passphrase will be used to encrypt the 929generating the key; the passphrase will be used to encrypt the
913sensitive part of this file using 3DES. 930sensitive part of this file using 3DES.
914.It Pa $HOME/.ssh/identity.pub 931.It Pa $HOME/.ssh/identity.pub
915Contains the public key for authentication (public part of the 932Contains the public key for authentication (public part of the
916identity file in human-readable form). 933identity file in human-readable form).
917The contents of this file should be added to 934The contents of this file should be added to
@@ -1031,7 +1048,7 @@ Additionally, successful RSA host authentication is normally
1031required. 1048required.
1032This file should only be writable by root. 1049This file should only be writable by root.
1033.It Pa /etc/shosts.equiv 1050.It Pa /etc/shosts.equiv
1034This file is processed exactly as 1051This file is processed exactly as
1035.Pa /etc/hosts.equiv . 1052.Pa /etc/hosts.equiv .
1036This file may be useful to permit logins using 1053This file may be useful to permit logins using
1037.Nm 1054.Nm
@@ -1048,7 +1065,7 @@ Commands in this file are executed by
1048.Nm 1065.Nm
1049when the user logs in just before the user's shell (or command) is 1066when the user logs in just before the user's shell (or command) is
1050started. 1067started.
1051See the 1068See the
1052.Xr sshd 8 1069.Xr sshd 8
1053manual page for more information. 1070manual page for more information.
1054.It Pa $HOME/.ssh/environment 1071.It Pa $HOME/.ssh/environment
@@ -1077,7 +1094,7 @@ external libraries.
1077has been updated to support ssh protocol 1.5, making it compatible with 1094has been updated to support ssh protocol 1.5, making it compatible with
1078all other ssh protocol 1 clients and servers. 1095all other ssh protocol 1 clients and servers.
1079.It 1096.It
1080contains added support for 1097contains added support for
1081.Xr kerberos 8 1098.Xr kerberos 8
1082authentication and ticket passing. 1099authentication and ticket passing.
1083.It 1100.It