With telnet most people know you can hit ^] to escape back to the program, but most people don’t realize that you can do a similar thing with OpenSSH. This is VERY helpful when your session dies. In OpenSSH the escape key is the tilde. Here is the segment from the OpenSSH manual.
*Escape Characters*
When a pseudo terminal has been requested, ssh supports a number of func-
tions through the use of an escape character.
A single tilde character can be sent as ~~ or by following the tilde by a
character other than those described below. The escape character must
always follow a newline to be interpreted as special. The escape charac-
ter can be changed in configuration files using the EscapeChar configura-
tion directive or on the command line by the -e option.
The supported escapes (assuming the default `~') are:
~. Disconnect
~^Z Background ssh
~# List forwarded connections
~& Background ssh at logout when waiting for forwarded connection /
X11 sessions to terminate
~? Display a list of escape characters
~C Open command line (only useful for adding port forwardings using
the -L and -R options)
~R Request rekeying of the connection (only useful for SSH protocol
version 2 and if the peer supports it)