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.
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.
Ken
mailto:[EMAIL PROTECTED]
http://www.sewingwitch.com/ken/
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