There is a patch for OpenSSH available here:
http://chaos2.org./~jacob/code/openssh/
...which adds a configuration directive TransmitInterlude to effectively
send ``pings'' (seems to be different to KeepAlive) at regular intervals
for the purpose of keeping an SSH connection open through a masquerade
(which otherwise times out).
The OpenSSH people do not seem to be particularly interested in making
this a permanent part of their project; please integrate it with the
Mandrake OpenSSH client.
--
"In America, anybody can be president.
That's one of the risks you take."
-- Adlai Stevenson (1900-1965)