At 09:19 PM 7/25/01, you wrote:
>On Tue, 24 Jul 2001 11:16:21 -1000, Clifton Royston wrote:
>
> >When we've seen similar problems, it's usually because TCP does *not*
> >see that the modem connection has gone away; they may have been
> >disconnected, but the old TCP connection is hanging around. I'm not
> >sure why the situation you describe would come up.
>
>A normal TCP connection will live forever without any packets. To get a
>timeout, you need to turn on "keepalives" after you create the
>connection. This forces a packet to be sent periodically, and kills the
>connection if the keepalives aren't seen frequently enough. I don't see
>any reference to keepalives in the qpopper source code, so unless the
>client asks for them, stale connections could have no indication that
>would cause qpopper to kill them. OTOH, your OS may provide keepalives
>by default. Linux, for instance, can be configured to use keepalives on
>all TCP connections using settings in /proc/sys/net/ipv4.
I've coded this and will give it a try. Good thinking.
>The modem bank should kill any outstanding TCP connections when a modem
>disconnects by sending a RST packet (I think) to the other end. But
>this won't protect you from a break in the connection somewhere else.
Some experiments I did the other day seem to indicate not all dialup
concentrators get this right...
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Daniel Senie [EMAIL PROTECTED]
Amaranth Networks Inc. http://www.amaranth.com
