diff options
Diffstat (limited to 'ssh.0')
| -rw-r--r-- | ssh.0 | 51 |
1 files changed, 30 insertions, 21 deletions
@@ -354,9 +354,9 @@ DESCRIPTION applications (eg. sftp(1)). The subsystem is specified as the remote command. - -T Disable pseudo-tty allocation. + -T Disable pseudo-terminal allocation. - -t Force pseudo-tty allocation. This can be used to execute + -t Force pseudo-terminal allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be very useful, e.g. when implementing menu services. Multiple -t options force tty allocation, even if ssh has no local tty. @@ -510,17 +510,22 @@ AUTHENTICATION whose host key is not known or has changed. When the user's identity has been accepted by the server, the server - either executes the given command, or logs into the machine and gives the - user a normal shell on the remote machine. All communication with the + either executes the given command in a non-interactive session or, if no + command has been specified, logs into the machine and gives the user a + normal shell as an interactive session. All communication with the remote command or shell will be automatically encrypted. - If a pseudo-terminal has been allocated (normal login session), the user - may use the escape characters noted below. + If an interactive session is requested ssh by default will only request a + pseudo-terminal (pty) for interactive sessions when the client has one. + The flags -T and -t can be used to override this behaviour. - If no pseudo-tty has been allocated, the session is transparent and can - be used to reliably transfer binary data. On most systems, setting the - escape character to M-bM-^@M-^\noneM-bM-^@M-^] will also make the session transparent even if - a tty is used. + If a pseudo-terminal has been allocated the user may use the escape + characters noted below. + + If no pseudo-terminal has been allocated, the session is transparent and + can be used to reliably transfer binary data. On most systems, setting + the escape character to M-bM-^@M-^\noneM-bM-^@M-^] will also make the session transparent + even if a tty is used. The session terminates when the command or shell on the remote machine exits and all X11 and TCP connections have been closed. @@ -638,16 +643,20 @@ VERIFYING HOST KEYS $ ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key If the fingerprint is already known, it can be matched and the key can be - accepted or rejected. Because of the difficulty of comparing host keys - just by looking at fingerprint strings, there is also support to compare - host keys visually, using random art. By setting the VisualHostKey - option to M-bM-^@M-^\yesM-bM-^@M-^], a small ASCII graphic gets displayed on every login to a - server, no matter if the session itself is interactive or not. By - learning the pattern a known server produces, a user can easily find out - that the host key has changed when a completely different pattern is - displayed. Because these patterns are not unambiguous however, a pattern - that looks similar to the pattern remembered only gives a good - probability that the host key is the same, not guaranteed proof. + accepted or rejected. If only legacy (MD5) fingerprints for the server + are available, the ssh-keygen(1) -E option may be used to downgrade the + fingerprint algorithm to match. + + Because of the difficulty of comparing host keys just by looking at + fingerprint strings, there is also support to compare host keys visually, + using random art. By setting the VisualHostKey option to M-bM-^@M-^\yesM-bM-^@M-^], a small + ASCII graphic gets displayed on every login to a server, no matter if the + session itself is interactive or not. By learning the pattern a known + server produces, a user can easily find out that the host key has changed + when a completely different pattern is displayed. Because these patterns + are not unambiguous however, a pattern that looks similar to the pattern + remembered only gives a good probability that the host key is the same, + not guaranteed proof. To get a listing of the fingerprints along with their random art for all known hosts, the following command line can be used: @@ -948,4 +957,4 @@ AUTHORS created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. -OpenBSD 5.7 March 3, 2015 OpenBSD 5.7 +OpenBSD 5.7 May 22, 2015 OpenBSD 5.7 |