From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Sun, 18 Apr 2010 19:52:04 -0400
To: 9fans@9fans.net
Message-ID: <ae24cc03d1ed549c7f22fea9af04a950@kw.quanstro.net>
In-Reply-To: <a9909b30f7af925a227f0796066c2620@plan9.bell-labs.com>
References: <a9909b30f7af925a227f0796066c2620@plan9.bell-labs.com>
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Subject: Re: [9fans] multiple pings cause panic
Topicbox-Message-UUID: 07c6481a-ead6-11e9-9d60-3106f5b1d025

On Sun Apr 18 16:41:17 EDT 2010, geoff@plan9.bell-labs.com wrote:
> There are limits on the number of concurrent conversations per
> protocol.  For UDP, it's currently 1024, for TCP it's currently 1024
> on terminals and 4096 on cpu servers.  For ICMP, it's currently 128;
> you may want to raise that.  To find the current limits,
>
> 	grep '>nc = ' /sys/src/9/ip/*.c

it's surprisingly easy to burn through connections since connections
can hang out in Finwait2 for a long time, burning up packets and
connections:

	; cpu -c 'cd /net.alt/tcp; x=1??? echo $x($#x)'
	1175

i haven't had time to take a look at this issue, but i wonder if acks
during Finwait2 are resetting the timer.  this is definately related
to smtp &/| pop.

i sometimes use this script as hostowner to clear out these
connections

	x=`{grep -l Finwait2 */status|sed 's:/status::g'}
	for(i in $x)
		if(~ `{cat $i^/local} *!110 *!25)
			>$i^/ctl echo hangup

- erik