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Date: Mon, 16 May 2016 18:36:50 +0100
From: Gary Palmer <gpalmer@freebsd.org>
To: Larry Rosenman <ler@lerctr.org>
Cc: Freebsd net <freebsd-net@freebsd.org>
Subject: Re: Closed port RST: Any way to find out what port(s)?
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On Mon, May 16, 2016 at 12:31:02PM -0500, Larry Rosenman wrote:
> I'm seeing tons of:
> Limiting closed port RST response from 201 to 200 packets/sec
> in my log.  Is there any way to see what port(s) are being pounded?

sysctl net.inet.tcp.log_in_vain=1

I expect you would get a ton of spam from that, so my suggestion would
be tcpdump.  e.g.

tcpdump -i <interface> -n 'tcp[tcpflags] & (tcp-rst) != 0'

Regards,

Gary