Re: [LARTC] MSN keeps disconnecting with load balancing

[Corey Hickey <bugfood-ml@fatooh.org>]

ro0ot wrote:
> Hi,
> 
> I have the my gateway with load balancing traffic going out over two 
> providers.  Web browsing is fine...working great.
> 
> But, my clients (office staff) complains that MSN keeps disconnecting 
> (in 5 mins).  Why?

Do you mean MSN instant messenger? I've never used it, but I can give
you a few generic steps to take when you want to figure out what's going
wrong with a connection. Are you familiar with tcpdump and/or ethereal?

1. Go to the computer of a client who is complaining about disconnection.

2. ssh into your gateway and run:
# tcpdump -i eth0 host 123.123.123.123 and port not ssh
Change "eth0" to the inside interface and "123.123.123.123" to the IP
address of your client.

3. See if tcpdump is catching lots and lots of packets. If it is, either
stop programs on your clients machine that access the Internet or use
more filters (like "and port not imaps").

4. Once you're not catching lots of extraneous packets, kill tcpdump and
run:
# tcpdump -s 1500 -w log -i eth0 host 123.123.123.123 and port not ssh
Include any other filters you have to use.

5. Have your client start up their program, and then sit there and wait.
Don't do anything else that would send packets through the gateway; you
don't want to clutter up the log.

6. See if the problem manifests. Most likely it won't, because that's
just the way things are :) , but if it does you'll have a log. Kill
tcpdump and examine the file with:
# tcpdump -r log
If you want more verbosity, use "-v", "-vv", or "-vvv". Or, if you want
to use a gui, copy the log file to some machine with X11 and use:
# ethereal -r log


-Corey
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