Re: Immortal connection

From: Jacob Luna Lundberg (
Date: Thu Mar 16 2000 - 11:51:23 EST

On Thu, 16 Mar 2000, Petr Sebor wrote:
> I have noticed that I do have an 'immortal' connection on my box. The client does
> connect over dialup with secure pop3, which is locally wrapped to insecure pop3. However,
> the connection still remains open a long time after the client has disconnected.
> ( read - terminated connection, the mail client disconnects after exitting ) I tried to
> watch communication between the remote host and my box, but there is no active packet exchange
> at all. I would rather suspect the is some -timeout- mechanism that would terminate the connection,
> transparently...

     This reminds me of a problem I (and some other people) have had with
ssh on linux, although more general than just over dialups. If I ssh to a
different box (over my 33.6kbps modem, over my cable-modem, etc.) the
connection will die after a while left unattended but it won't notice it
until I come back and press a key. I found out recently that in my case,
anyway, it _is_ related to a timeout. Specifically, the tcp keepalive
time on linux defaults to 7200 seconds, which is apparently too long for
ssh. Ssh seems to like it better if you set
/proc/sys/net/ipv4/tcp_keepalive_time to something around of 300 seconds.

     I read somewhere that this is supposed to make both sides notice when
the connection is down if they're both using it. Of course, it could also
be completely unrelated to your problem. ;-)

> Is this normal ? I'm using 2.2.15pre14, but I have observed this quite some time ago with
> older pre releases, but on connection comming ONLY from dialups. Is there anything that I may
> look for ?

     I've seen the above issue since sometime in the 2.1.x series all the
way up through the 2.3.x series.



"Heh. You mean this is Stef's source code?" -User Friendly

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