[lug] An odd networking question

[Sean Reifschneider]

On 10/15/2009 08:09 PM, Kenneth D Weinert wrote:
> Anyone have any pointers on what to search for, things to read, etc to
> help me get this sorted out?

This sounds like an isolation problem.  To make the inevitable car analogy,
you were kind of saying "My car doesn't work on the highway and it doesn't
work on the Interstate and it doesn't work on the city streets."  The
descriptions of the problems were all rather high level (I can't get
e-mail).

Like with the car, there are a bunch of components that need to work before
you can get to the highway -- does the door work, can you start the car,
have you opened the garage door...

For getting on the network, there are individual components, each of which
tells you something about the problem:

   Do you have an IP address on the local network?  (ifconfig)

   Do you have a default gateway?  (netstat -nr)

   Can you ping that gateway?  (ping -n $GATEWAYIP)

   Can you resolve the name of your mail server?  (host mail.example.com)

   Can you ping your mail server?  (ping mail.example.com)

   Can you connect to your SMTP server?
         (printf 'quit\n' | nc mail.example.com 25)

It sounds like going through this set of checks might have given you a
pointer to the problem.

There are other problems that can exist between the steps above, but these
are some of the first things that I look at when I am having networking
problems.

Sean
-- 
Sean Reifschneider, Member of Technical Staff <jafo at tummy.com>
tummy.com, ltd. - Linux Consulting since 1995: Ask me about High Availability

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