ssh -t shmem@gateway ssh -t admin@host.example.com \
  ssh -t wrxd15@192.168.123.2 ssh -t root@192.168.254.2

##</code><code>##

# .ssh/config
Host foo
ProxyCommand ssh me@my.server.org         \
  ssh me@other.server.org                 \
  ssh root@foo.server.org /usr/sbin/sshd -i

##</code><code>##

ssh foo