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Trying to Help a Troubled Network with Linux?
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?"
First step isn't to blunder in and migrate - the first step is to work out what's causing the outages etc. use ethereal or some other packet sniffer to establish where the broadcast floods are coming from - use nmap to find insecure hosts - also, investigate what kind of routers are being used, and what rules are being employed.
Basically, OSS/Linux are great, but don't rush in without establishing the issues first.
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.
The first step in troubleshooting is in knowing the network topology. How are network segments separated? How are the connected? Where are routers, hubs, switches, etc.? Which switches are managed, and how are the VLANs set up on them? Where are the DHCP servers, and what do they serve? Where are all your network drops?
Do your network segments have multiple subnets attached to them?
Is everything subnetted properly?
The first set of questions are ones YOU should be able to answer. After all, it's YOUR network, and YOU should know how it's set up. The last two are harder to deal with, because these settings may be on computers not in your control.
Answer the first questions first, then when you are looking at packet traces, TCP/IP dumps, logs, etc. and you see a problem, you'll have a better idea where the problem is physically located, saving much time and energy.
And then there's the "dumb questions" I shouldn't have to ask: Do you have a loop? Are your cables wired to T568A or T568B standards? Are all your cables in good repair?
Give me my freedom, and I'll take care of my own security, thank you.
Without any more information, you've got a bad NIC, almost certainly. Look on the switch for the port whose light is always on. As you've describe it, software has almost nothing to do with it. This is a NIC, or a bad switch, or bad cabling, or something.
"He who would learn astronomy, and other recondite arts, let him go elsewhere. " -- John Calvin, commenting on Genesis 1
Go on, mod me 'insightfull' or mod me 'flamebait', it's one or the other.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
I have a better idea. Get Linux and slap it on all your windows boxes and be done. For good.
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