ssh

SSH Escape Sequence:
Supported escape sequences:
~ . ----- terminate connection that got hanged
~ ^ Z -----suspend ssh --- to send the ssh-connection to background
~ #  ----- 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 a newline.)


References:
http://rcsg-gsir.imsb-dsgi.nrc-cnrc.gc.ca/documents/internet/node30.html