How to drop TCP connection without killing process?
lcook at sybase.com
Mon May 24 16:43:00 EDT 2004
> What you're asking for is kindof weird
Yes, I guess it is. Let me explain:
A POP3 server I use doesn't send a response on occasion. This causes Mozilla
to stop checking that POP3 account because the connection is still up. And
the connection just stays up, with no traffic, as far as I can tell. I'd like
to force that connection to drop so that Mozilla will start checking that
account again. And I like to do this without having to stop and restart Mozilla.
> but one way of accomplishing
> what you're asking for is to use something like ipchains
I guess this won't be useful since there does not appear to be any traffic on
> This might be useful:
> tcpdump 'host my-computer tcp port my-local-port'
> If there are any keepalives being sent, tcpdump WILL see them.
That is what I am doing, so I guess Mozilla must not use keepalives.
> Although I need to tell you up front that:
> 1: by default, TCP doesn't use ANY keepalives. The application
> that uses a TCP session needs to enable these manually.
> 2: If TCP keepalives are enabled, typically these keepalives are
> sent out every few hours or so. So, if you're waiting to see
> an elusive TCP keepalive, you might be waiting for a while.
> Applications that need some sort of keepalive feature
> (especially if these are short) have to implement these things
> themselves and not depend on TCP's keepalive feature.
Thanks for the explaination of keepalives. I'll leave tcpdump running
overnight just to confirm there are no keepalives. I guess Mozilla needs a
timeout when waiting for POP3 responses.
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