SSH
A generic term referring to SSH protocols or software products.
SSH-1
The SSH protocol, Version 1. This protocol went through several
revisions, of which 1.3 and 1.5 are the best known, and we will
write SSH-1.3 and SSH-1.5 should the distinction be necessary.
SSH-2
The SSH protocol, Version 2, as defined by several draft standards
documents of the IETF SECSH working group.
SSH1
Tatu Ylönen's software implementing the SSH-1 protocol; the original
SSH. Now distributed and maintained (minimally) by SSH
Communications Security, Inc.
SSH2
The "SSH Secure Shell" product from SSH Communications Security, Inc.
This is a commercial SSH-2 protocol implementation, though it is
licensed free of charge in some circumstances.
ssh (all lowercase letters)
A client program included in SSH1, SSH2, OpenSSH, F-Secure SSH, and
other products, for running secure terminal sessions and remote
commands. In SSH1 and SSH2, it is also named ssh1/ssh2, respectively.
OpenSSH
The product OpenSSH from the OpenBSD project,
which implements both the SSH-1 and SSH-2 protocols.
OpenSSH/1
OpenSSH, referring specifically to its behavior
when using the SSH-1 protocol.
OpenSSH/2
OpenSSH, referring specifically to its behavior
when using the SSH-2 protocol.
SSH client 有一個 Escape Character (跳脫字元)，事實上 rsh/rlogin 也有支援 Escape Character (~)，就如同 Ctrl-] 之於 telnet 一樣…
SSH client 的 Escape Character 一般跟 rsh/rlogin 一樣設定成 ~，詳細用法可於命令列按 ~? 來取得說明，要注意的是，為了避免影響一般正常的輸入，Escape Character 必須是命令列換行後的第一個按鍵，如果你已經輸入別的按鍵，即使按 backspace 把游標移回開頭處再輸入 Escape Character 也是無效的！請先按 Enter 換行後再輸入吧！
myhost# ~?
Supported escape sequences:
~. - terminate connection
~B - send a BREAK to the remote system
~C - open a command line
~R - Request rekey (SSH protocol 2 only)
~^Z - suspend ssh
~# - list forwarded connections
~& - background ssh (when waiting for connections to terminate)
~? - this message
~~ - send the escape character by typing it twice
(Note that escapes are only recognized immediately after newline.)
Following the previous notes about enabling core dump, here’s a note about changing the filename of core dump.
In Linux (since Linux 2.6 and 2.4.21)
you can change the core dump filename from the file /proc/sys/kernel/core_pattern
%% A single % character
%p PID of dumped process
%u real UID of dumped process
%g real GID of dumped process
%s number of signal causing dump
%t time of dump (seconds since 0:00h, 1 Jan 1970)
%h hostname (same as 'nodename' returned by uname(2))
%e executable filename
Linux have a default core filename pattern of “core”.
Alternatively, if /proc/sys/kernel/core_uses_pid contains a non-zero value, then the core dump file name will include a suffix .PID (process id), ex: core.PID
In FreeBSD, sysctl variable “kern.corefile” controls the filename of core dump.
Any sequence of %N in this filename template will be replaced by
the process name, %P by the processes PID, and %U by the UID.
FreeBSD have a default core filename pattern of “%N.core”
You can include path in the filename pattern both in Linux and FreeBSD.
This make it possible to put core dump file in a separated directory.
