Subject: Re: ports beeing reused too fast

From: Stephen Hemminger <[email-masked]>
Date: Tue, 12 May 2009 08:11:19 -0700

On Tue, 12 May 2009 15:32:57 +0300
Octavian Purdila <[email-masked]> wrote:

> 
> > > > >> Any strong reason why a firewall would drop a SYN because ports were
> > > > >> used in a previous session ?
> > > > >
> > > > > We don't know why the firewall (Cisco FWSM) is dropping the packets,
> > > > > may be a bug, limitation or miss-configuration. We are trying to
> > > > > track this down with the firewall vendor.
> > > >
> 
> Interestingly, we are seeing the same behavior with another high-end firewall 
> (Juniper SRX). 
> 
> As mentioned previously, this can not be caused by the TW state, because the 
> connections are getting closed on the server side.
> 
> Thanks,
> tavi

I raised the issue to the original author of the proposed RFC and added
the issue to the ongoing review of the draft.

There is a suggested workaround using a bitmap but it seems like it would be
expensive to implement:
       http://ietfreport.isoc.org/all-ids/draft-ananth-tsvwg-timewait-00.txt

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