diff options
Diffstat (limited to 'ssh.1')
-rw-r--r-- | ssh.1 | 89 |
1 files changed, 53 insertions, 36 deletions
@@ -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 |
55 | executing commands on a remote machine. | 55 | executing commands on a remote machine. |
@@ -60,7 +60,7 @@ X11 connections and | |||
60 | arbitrary TCP/IP ports can also be forwarded over the secure channel. | 60 | arbitrary TCP/IP ports can also be forwarded over the secure channel. |
61 | .Pp | 61 | .Pp |
62 | .Nm | 62 | .Nm |
63 | connects and logs into the specified | 63 | connects and logs into the specified |
64 | .Ar hostname . | 64 | .Ar hostname . |
65 | The user must prove | 65 | The user must prove |
66 | his/her identity to the remote machine using one of several methods. | 66 | his/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 |
72 | on the remote machine, and the user names are | 72 | on the remote machine, and the user names are |
73 | the same on both sides, the user is immediately permitted to log in. | 73 | the same on both sides, the user is immediately permitted to log in. |
74 | Second, if | 74 | Second, if |
75 | .Pa \&.rhosts | 75 | .Pa \&.rhosts |
76 | or | 76 | or |
77 | .Pa \&.shosts | 77 | .Pa \&.shosts |
@@ -94,7 +94,7 @@ It means that if the login would be permitted by | |||
94 | or | 94 | or |
95 | .Pa /etc/shosts.equiv , | 95 | .Pa /etc/shosts.equiv , |
96 | and if additionally the server can verify the client's | 96 | and if additionally the server can verify the client's |
97 | host key (see | 97 | host key (see |
98 | .Pa /etc/ssh_known_hosts | 98 | .Pa /etc/ssh_known_hosts |
99 | and | 99 | and |
100 | .Pa $HOME/.ssh/known_hosts | 100 | .Pa $HOME/.ssh/known_hosts |
@@ -109,17 +109,17 @@ spoofing, DNS spoofing and routing spoofing. | |||
109 | and the rlogin/rsh protocol in general, are inherently insecure and should be | 109 | and the rlogin/rsh protocol in general, are inherently insecure and should be |
110 | disabled if security is desired.] | 110 | disabled if security is desired.] |
111 | .Pp | 111 | .Pp |
112 | As a third authentication method, | 112 | As a third authentication method, |
113 | .Nm | 113 | .Nm |
114 | supports RSA based authentication. | 114 | supports RSA based authentication. |
115 | The scheme is based on public-key cryptography: there are cryptosystems | 115 | The scheme is based on public-key cryptography: there are cryptosystems |
116 | where encryption and decryption are done using separate keys, and it | 116 | where encryption and decryption are done using separate keys, and it |
117 | is not possible to derive the decryption key from the encryption key. | 117 | is not possible to derive the decryption key from the encryption key. |
118 | RSA is one such system. | 118 | RSA is one such system. |
119 | The idea is that each user creates a public/private | 119 | The idea is that each user creates a public/private |
120 | key pair for authentication purposes. | 120 | key pair for authentication purposes. |
121 | The server knows the public key, and only the user knows the private key. | 121 | The server knows the public key, and only the user knows the private key. |
122 | The file | 122 | The file |
123 | .Pa $HOME/.ssh/authorized_keys | 123 | .Pa $HOME/.ssh/authorized_keys |
124 | lists the public keys that are permitted for logging | 124 | lists the public keys that are permitted for logging |
125 | in. | 125 | in. |
@@ -142,18 +142,18 @@ key but without disclosing it to the server. | |||
142 | implements the RSA authentication protocol automatically. | 142 | implements the RSA authentication protocol automatically. |
143 | The user creates his/her RSA key pair by running | 143 | The user creates his/her RSA key pair by running |
144 | .Xr ssh-keygen 1 . | 144 | .Xr ssh-keygen 1 . |
145 | This stores the private key in | 145 | This stores the private key in |
146 | .Pa \&.ssh/identity | 146 | .Pa \&.ssh/identity |
147 | and the public key in | 147 | and the public key in |
148 | .Pa \&.ssh/identity.pub | 148 | .Pa \&.ssh/identity.pub |
149 | in the user's home directory. | 149 | in the user's home directory. |
150 | The user should then copy the | 150 | The user should then copy the |
151 | .Pa identity.pub | 151 | .Pa identity.pub |
152 | to | 152 | to |
153 | .Pa \&.ssh/authorized_keys | 153 | .Pa \&.ssh/authorized_keys |
154 | in his/her home directory on the remote machine (the | 154 | in his/her home directory on the remote machine (the |
155 | .Pa authorized_keys | 155 | .Pa authorized_keys |
156 | file corresponds to the conventional | 156 | file corresponds to the conventional |
157 | .Pa \&.rhosts | 157 | .Pa \&.rhosts |
158 | file, and has one key | 158 | file, and has one key |
159 | per line, though the lines can be very long). | 159 | per line, though the lines can be very long). |
@@ -167,7 +167,7 @@ See | |||
167 | .Xr ssh-agent 1 | 167 | .Xr ssh-agent 1 |
168 | for more information. | 168 | for more information. |
169 | .Pp | 169 | .Pp |
170 | If other authentication methods fail, | 170 | If other authentication methods fail, |
171 | .Nm | 171 | .Nm |
172 | prompts the user for a password. | 172 | prompts the user for a password. |
173 | The password is sent to the remote | 173 | The password is sent to the remote |
@@ -188,7 +188,7 @@ and suspend | |||
188 | with | 188 | with |
189 | .Ic ~^Z . | 189 | .Ic ~^Z . |
190 | All forwarded connections can be listed with | 190 | All forwarded connections can be listed with |
191 | .Ic ~# | 191 | .Ic ~# |
192 | and if | 192 | and if |
193 | the session blocks waiting for forwarded X11 or TCP/IP | 193 | the session blocks waiting for forwarded X11 or TCP/IP |
194 | connections to terminate, it can be backgrounded with | 194 | connections to terminate, it can be backgrounded with |
@@ -232,7 +232,7 @@ Forwarding of X11 connections can be | |||
232 | configured on the command line or in configuration files. | 232 | configured on the command line or in configuration files. |
233 | .Pp | 233 | .Pp |
234 | The | 234 | The |
235 | .Ev DISPLAY | 235 | .Ev DISPLAY |
236 | value set by | 236 | value set by |
237 | .Nm | 237 | .Nm |
238 | will point to the server machine, but with a display number greater | 238 | will 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 |
266 | automatically maintains and checks a database containing RSA-based | 266 | automatically maintains and checks a database containing RSA-based |
267 | identifications for all hosts it has ever been used with. | 267 | identifications for all hosts it has ever been used with. |
268 | The database is stored in | 268 | The database is stored in |
269 | .Pa \&.ssh/known_hosts | 269 | .Pa \&.ssh/known_hosts |
270 | in the user's home directory. | 270 | in the user's home directory. |
271 | Additionally, the file | 271 | Additionally, the file |
272 | .Pa /etc/ssh_known_hosts | 272 | .Pa /etc/ssh_known_hosts |
273 | is automatically checked for known hosts. | 273 | is automatically checked for known hosts. |
274 | Any new hosts are automatically added to the user's file. | 274 | Any new hosts are automatically added to the user's file. |
@@ -290,10 +290,10 @@ host key is not known or has changed. | |||
290 | Disables forwarding of the authentication agent connection. | 290 | Disables forwarding of the authentication agent connection. |
291 | This may also be specified on a per-host basis in the configuration file. | 291 | This 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 |
293 | Selects the cipher to use for encrypting the session. | 293 | Selects the cipher to use for encrypting the session. |
294 | .Ar 3des | 294 | .Ar 3des |
295 | is used by default. | 295 | is used by default. |
296 | It is believed to be secure. | 296 | It 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. |
299 | It is presumably more secure than the | 299 | It is presumably more secure than the |
@@ -322,7 +322,7 @@ This is useful if | |||
322 | .Nm | 322 | .Nm |
323 | is going to ask for passwords or passphrases, but the user | 323 | is going to ask for passwords or passphrases, but the user |
324 | wants it in the background. | 324 | wants it in the background. |
325 | This implies | 325 | This implies |
326 | .Fl n . | 326 | .Fl n . |
327 | The recommended way to start X11 programs at a remote site is with | 327 | The recommended way to start X11 programs at a remote site is with |
328 | something like | 328 | something like |
@@ -330,9 +330,9 @@ something like | |||
330 | .It Fl g | 330 | .It Fl g |
331 | Allows remote hosts to connect to local forwarded ports. | 331 | Allows remote hosts to connect to local forwarded ports. |
332 | .It Fl i Ar identity_file | 332 | .It Fl i Ar identity_file |
333 | Selects the file from which the identity (private key) for | 333 | Selects the file from which the identity (private key) for |
334 | RSA authentication is read. | 334 | RSA authentication is read. |
335 | Default is | 335 | Default is |
336 | .Pa \&.ssh/identity | 336 | .Pa \&.ssh/identity |
337 | in the user's home directory. | 337 | in the user's home directory. |
338 | Identity files may also be specified on | 338 | Identity files may also be specified on |
@@ -548,6 +548,12 @@ and | |||
548 | are supported. | 548 | are supported. |
549 | The default is | 549 | The default is |
550 | .Dq 3des . | 550 | .Dq 3des . |
551 | .It Cm Ciphers | ||
552 | Specifies the ciphers allowed for protocol version 2 | ||
553 | in order of preference. | ||
554 | Multiple ciphers must be comma-separated. | ||
555 | The default is | ||
556 | .Dq blowfish-cbc,3des-cbc,arcfour,cast128-cbc . | ||
551 | .It Cm Compression | 557 | .It Cm Compression |
552 | Specifies whether to use compression. | 558 | Specifies whether to use compression. |
553 | The argument must be | 559 | The argument must be |
@@ -577,12 +583,12 @@ followed by a letter, or | |||
577 | to disable the escape | 583 | to disable the escape |
578 | character entirely (making the connection transparent for binary | 584 | character entirely (making the connection transparent for binary |
579 | data). | 585 | data). |
580 | .It Cm FallBackToRsh | 586 | .It Cm FallBackToRsh |
581 | Specifies that if connecting via | 587 | Specifies that if connecting via |
582 | .Nm | 588 | .Nm |
583 | fails due to a connection refused error (there is no | 589 | fails due to a connection refused error (there is no |
584 | .Xr sshd 8 | 590 | .Xr sshd 8 |
585 | listening on the remote host), | 591 | listening on the remote host), |
586 | .Xr rsh 1 | 592 | .Xr rsh 1 |
587 | should automatically be used instead (after a suitable warning about | 593 | should automatically be used instead (after a suitable warning about |
588 | the session being unencrypted). | 594 | the session being unencrypted). |
@@ -599,10 +605,10 @@ or | |||
599 | .Dq no . | 605 | .Dq no . |
600 | .It Cm ForwardX11 | 606 | .It Cm ForwardX11 |
601 | Specifies whether X11 connections will be automatically redirected | 607 | Specifies whether X11 connections will be automatically redirected |
602 | over the secure channel and | 608 | over the secure channel and |
603 | .Ev DISPLAY | 609 | .Ev DISPLAY |
604 | set. | 610 | set. |
605 | The argument must be | 611 | The argument must be |
606 | .Dq yes | 612 | .Dq yes |
607 | or | 613 | or |
608 | .Dq no . | 614 | .Dq no . |
@@ -618,7 +624,7 @@ or | |||
618 | The default is | 624 | The default is |
619 | .Dq no . | 625 | .Dq no . |
620 | .It Cm GlobalKnownHostsFile | 626 | .It Cm GlobalKnownHostsFile |
621 | Specifies a file to use instead of | 627 | Specifies 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 |
624 | Specifies the real host name to log into. | 630 | Specifies the real host name to log into. |
@@ -697,6 +703,17 @@ or | |||
697 | .It Cm Port | 703 | .It Cm Port |
698 | Specifies the port number to connect on the remote host. | 704 | Specifies the port number to connect on the remote host. |
699 | Default is 22. | 705 | Default is 22. |
706 | .It Cm Protocol | ||
707 | Specifies the protocol versions | ||
708 | .Nm | ||
709 | should support in order of preference. | ||
710 | The possible values are | ||
711 | .Dq 1 | ||
712 | and | ||
713 | .Dq 2 . | ||
714 | Multiple versions must be comma-separated. | ||
715 | The default is | ||
716 | .Dq 1 . | ||
700 | .It Cm ProxyCommand | 717 | .It Cm ProxyCommand |
701 | Specifies the command to use to connect to the server. | 718 | Specifies the command to use to connect to the server. |
702 | The command | 719 | The command |
@@ -773,7 +790,7 @@ The default is | |||
773 | .Dq no . | 790 | .Dq no . |
774 | .It Cm StrictHostKeyChecking | 791 | .It Cm StrictHostKeyChecking |
775 | If this flag is set to | 792 | If this flag is set to |
776 | .Dq yes , | 793 | .Dq yes , |
777 | .Nm | 794 | .Nm |
778 | ssh will never automatically add host keys to the | 795 | ssh 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: | |||
839 | The | 856 | The |
840 | .Ev DISPLAY | 857 | .Ev DISPLAY |
841 | variable indicates the location of the X11 server. | 858 | variable indicates the location of the X11 server. |
842 | It is automatically set by | 859 | It is automatically set by |
843 | .Nm | 860 | .Nm |
844 | to point to a value of the form | 861 | to point to a value of the form |
845 | .Dq hostname:n | 862 | .Dq hostname:n |
@@ -885,10 +902,10 @@ on to new connections). | |||
885 | Set to the name of the user logging in. | 902 | Set to the name of the user logging in. |
886 | .El | 903 | .El |
887 | .Pp | 904 | .Pp |
888 | Additionally, | 905 | Additionally, |
889 | .Nm | 906 | .Nm |
890 | reads | 907 | reads |
891 | .Pa $HOME/.ssh/environment , | 908 | .Pa $HOME/.ssh/environment , |
892 | and adds lines of the format | 909 | and adds lines of the format |
893 | .Dq VARNAME=value | 910 | .Dq VARNAME=value |
894 | to the environment. | 911 | to the environment. |
@@ -911,7 +928,7 @@ ignores this file if it is accessible by others. | |||
911 | It is possible to specify a passphrase when | 928 | It is possible to specify a passphrase when |
912 | generating the key; the passphrase will be used to encrypt the | 929 | generating the key; the passphrase will be used to encrypt the |
913 | sensitive part of this file using 3DES. | 930 | sensitive part of this file using 3DES. |
914 | .It Pa $HOME/.ssh/identity.pub | 931 | .It Pa $HOME/.ssh/identity.pub |
915 | Contains the public key for authentication (public part of the | 932 | Contains the public key for authentication (public part of the |
916 | identity file in human-readable form). | 933 | identity file in human-readable form). |
917 | The contents of this file should be added to | 934 | The contents of this file should be added to |
@@ -1031,7 +1048,7 @@ Additionally, successful RSA host authentication is normally | |||
1031 | required. | 1048 | required. |
1032 | This file should only be writable by root. | 1049 | This file should only be writable by root. |
1033 | .It Pa /etc/shosts.equiv | 1050 | .It Pa /etc/shosts.equiv |
1034 | This file is processed exactly as | 1051 | This file is processed exactly as |
1035 | .Pa /etc/hosts.equiv . | 1052 | .Pa /etc/hosts.equiv . |
1036 | This file may be useful to permit logins using | 1053 | This 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 |
1049 | when the user logs in just before the user's shell (or command) is | 1066 | when the user logs in just before the user's shell (or command) is |
1050 | started. | 1067 | started. |
1051 | See the | 1068 | See the |
1052 | .Xr sshd 8 | 1069 | .Xr sshd 8 |
1053 | manual page for more information. | 1070 | manual page for more information. |
1054 | .It Pa $HOME/.ssh/environment | 1071 | .It Pa $HOME/.ssh/environment |
@@ -1077,7 +1094,7 @@ external libraries. | |||
1077 | has been updated to support ssh protocol 1.5, making it compatible with | 1094 | has been updated to support ssh protocol 1.5, making it compatible with |
1078 | all other ssh protocol 1 clients and servers. | 1095 | all other ssh protocol 1 clients and servers. |
1079 | .It | 1096 | .It |
1080 | contains added support for | 1097 | contains added support for |
1081 | .Xr kerberos 8 | 1098 | .Xr kerberos 8 |
1082 | authentication and ticket passing. | 1099 | authentication and ticket passing. |
1083 | .It | 1100 | .It |