I think you are spot on David. xinetd has a default of 60 instances per
daemon active at one time. This is configurable in xinetd.conf or in the
individual config files for each daemon. The 7.2 default, again, is 60
per daemon and the default rsh config file does not override that
default. My guess is that at the rate he is spawning rsh processes that
by the time he gets near 500 there are still 60 open rsh connections so
xinetd refuses to start any additional rsh instances. The fix would be to
put an instance line in /etc/xinetd.d/rsh with some higher value, say 200,
then restart xinetd and test.
- rick -
On Sat, 9 Mar 2002, David Talkington wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Rhugga wrote:
>
> >
> >We are having problems with rsh on 7.2 machines. We are doing massive
> >rsh connections on a 250-node cluster executing PVM jobs. We reach a
> >point where we get the following error: (single machine test)
> >
> >poll: protocol failure in circuit setup
> >
> >It happens around 500 or so connections. I wrote test scripts that
> >spawned rsh connections in sequence doing a simple 'uname -S' and
> >found that near 500 connections this error would occur. Note: It is
> >not always the same amount, it may be 497, 495, 499, but never 500.
> >
> >Is there a limit on open sockets or is there a limitation in in.rshd?
> >These machines are otherwise idle when these tests are being ran.
>
> My instinct would be to point the finger at xinetd. inetd's
> performance in this regard was known to suck; I don't know how xinetd
> compares, but I'd suspect it.
>
> I won't presume to know what's best for your situation, but there are
> usually better options than rsh -- ssh being the obvious one, and it's
> a lot faster than you might think, if you use a good algorithm such as
> blowfish. Another option for rshd might be to use a more robust
> services daemon such as tcpserver; http://cr.yp.to/ucspi-tcp.html.
>
> Just some thoughts.
>
> - -d
>
>
> - --
> David Talkington
>
> PGP key: http://www.prairienet.org/~dtalk/0xCA4C11AD.pgp
> - --
> http://setiathome.ssl.berkeley.edu/pale_blue_dot.html
>
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