TCP keepalive seems to send to only one port

From: Cesar Eduardo Barros (cesarb@nitnet.com.br)
Date: Sat Dec 23 2000 - 18:31:56 EST


I've been doing some experiments with the keepalive code in 2.4.0-test10 here
(I want to avoid the 2.2.x NAT I'm using (for which I don't have root) from
 timing out my connections). To test it, I reduced both tcp_keepalive_time and
tcp_keepalive_intvl to 1. Using ethereal, I saw that the keepalives were sent
as expected, but only for one of the two idle TCP connections I had to a given
host (I was testing with two remote hosts, each with two idle TCP connections,
one in port 5500 and the other in port 5501). I only saw activity on 5500, yet
netstat told me both were still active.

This means that keepalive is useless for keeping alive more than one connection
to a given host.

-- 
Cesar Eduardo Barros
cesarb@nitnet.com.br
cesarb@dcc.ufrj.br
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