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Trying to Help a Troubled Network with Linux?

Posted by Cliff on from the penguin-packet-protection dept.

vmehta asks: "I was recently put in a situation where I am trying to help a troubled network with many students accessing it. There are issues with broadcast packets and random outages which seem to be plaguing the network. What tools and methods are the best practice when trying to use Linux and Open Source to analyze and fix a network?"

2 of 68 comments (clear)

  1. You are infected with viruses most likely by Anonymous+Crowhead · · Score: 5, Insightful

    Almost any time I see this, its some random box flooding the network. Just go to your switches...the light that is on solid continuously will point you in the right direction.

  2. map, isolate, trend by grattwood · · Score: 5, Informative

    Step 1) Map the network both logically (which networks, what is the routing, etc.) and physically... the "tug test". Label everything, and put it all in a spreadsheet. Tools are nmap, pen and paper, and a label printer. Access to the routers, or being friendly the the router admin is a must.

    Step 2) Isolate the problem protocols and hosts. Be on the lookout for appletalk, IPX, or old netbios. All very chatty protocols. Look for old hubs and replace them with switches. Look for comprimised boxen. Try to VLAN things logically (by department, or usage which ever is best for the environment). Tools are snort, ethereal, ntop, and syslog (any managed switches should be sending to a syslog server (I've used syslog-ng))

    Step 3) Trend as much as you can. Even before the network is cleaned up, start to collect statistics from the switches, and/or hosts on your network. Any gateways should be monitored as well. This will let you see if there are problems corelated to a particular time of day, if your're going over your bandwidth etc. Tools are MRTG, or for more in depth try Cacti http://www.cacti.net/

    There is much more after you get to this point, but people will be much happier the faster you get here.

    Good luck