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Old 01-03-2011, 03:50 AM   #1
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Question RHEL Server is Broadcasting on LAN and Choking the Network

I have a RHEL 5 Server dedicated to web hosting. HTTPD 2.2.x.x is running on it with PHP and MySQL. The machine is not a server system (hardware wise, a C2D 2.66 with 2GB RAM and 2 x NICs).

I have a CIR Fiber link with a pool of live IPs. The machines including this web server is plugged into a switch which has all the live interfaces and is separate from the LAN switches.

The problem i am facing is that, when ever this web server is plugged in, the traffic on live switch is choked. Internet slows down to a halt (as live interface of proxy is plugged in this switch. DNS stops resolving name due to time outs. Mail delivery is slowed and the mail ques pile ups. The moment i get this machine of the switch, all the traffic becomes normal. Therefore i have deduced that this is the faulty server. I do not know if this server is hacked and working as a bot or it is a mere hardware problem(faulty LAN Card).

A guidance towards the identification and resolution of this problem is requested from all the members.

I have put my server offline. I can do that for long, or the management may want to shift to windows server. I hate windows, please tell me what to do.
Old 01-03-2011, 04:05 AM   #2
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Well you need to see wht the traffic is, don't you? use a tool like tcpdump or wireshark to capture some of the traffic leaving its nic and see what it is.
Old 01-03-2011, 04:33 AM   #3
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Sounds like a switching loop to me. I'd break out tcpdump/wireshark as above and look for lots of broadcast traffic.

Old 01-03-2011, 10:52 AM   #4
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Put it on a spare switch along with your laptop.

See if the problem persists (ie, bandwidth bottleneck)

Change the NIC in the machine, try again.

If it still persists, then you will have to look at the configuration of the machine. Make sure that IP6 is disabled (as long as you are not using it), then check the traffic again.

in short, With what little info you have given, I would guess that it is a bad NIC or a box that is configured with IP6 still.


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