[TriLUG] ssh 'through' a firewall

[Douglas Kojetin]

hi all-

i ssh to a computer computer behind a firewall that has access to other 
computers behind the network that i frequently need to ssh to.  what i 
normally do is

ssh user at firstcomputer
ssh user at secondcomputer

is there a shortcut i can take so that i don't ssh twice?  i've setup 
aliases and 'no-password authentication' to ease things, but it would 
be nice to do the above in one command if possible.

thanks!
doug