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Date:      Thu, 15 Feb 2001 23:36:30 +0000 (GMT)
From:      Andrew Gordon <arg@arg1.demon.co.uk>
To:        "Morten A . Middelthon" <morten@freenix.no>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: Portmap going berserk(!)
Message-ID:  <Pine.BSF.4.21.0102152319120.583-100000@server.arg.sj.co.uk>
In-Reply-To: <20010215192135.A95579@freenix.no>

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On Thu, 15 Feb 2001, Morten A . Middelthon wrote:

> I got a FreeBSD 4.1.1-STABLE built Oct 8, which seems to have been running just
> fine for about 40 days. But now, all of a sudden, portmap forks off nnn
> processes, and the load on the box goes up to about 150 (not kidding). Running

I've seen over 400...

> portmap with -v doesn't give me anything, running it with -d starts spitting
> out thousands of 'server: about to do a switch' messages to my console. I
> tried rebooting the box, but it starts all over again.

You want to reboot the NIS client boxes which are bashing it, rather than
the machine itself.

> The box is running as a DHCP, NFS, Samba, NIS, Apache, named and printserver,
> so it's quite an important box in my network.
> 
> Is there any known portmap-related problems? Right now I'm building with new
> updated sources, hoping desperately it will help.

I don't think it will help.  This is a known problem (there's a few
messages in the archives).  I suspect the reason noone's fixed it is that
it's hard to reproduce, and in the kind of situation where you do
reproduce it (NIS server in large network with lots of traffic), there
isn't much opportunity to investigate because the 'phones are ringing like
crazy with all the users that can't log in...

The work-around is to list all your NIS servers explicitly (described as
"many-cast" in the ypbind manpage) rather than broadcasting.

The few times it's happened to me, I observed:

1) Each time it happened, it was preceded by some kind of network packet
loss incident (one time it was a bad ethernet switch, another time a dud
cable).  This merely seems to trigger the problem: once the problem has
started, you can mend the network but the problem won't go away until you
reboot all the servers.

2) When this is going on, the symptoms are that one or more NIS clients
are churning out vast quantities of broadcasts.  The portmapper on the NIS
server dutifully tries to reply to each one, but the client isn't
listening to the replies.  A tcpdump trace goes something like:

client.xxx->broadcast.portmap  UDP <request for ypserv>
server.portmap->client.xxx     UDP <reply>
client->server         ICMP port unreachable






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