[ILUG] Question about networks and interfaces on a laptop

From: Anthony Staines (anthony.staines at domain ucd.ie)
Date: Mon 27 May 2002 - 10:37:31 IST


Hi,

I run Red Hat 7.2 on a laptop, which moves between work, where it gets a
fixed IP address on eth0 (network card) and home, where it picks up an
IP address courtesy of Eircom on ppp0 (a modem). So far so fine.

Both of these work nicely, except that when at home I can't access my
work websites, or the servers here. I get '-Site- could not be found'
messages in Mozilla. I can't ping them, and I can't traceroute them by
name. In fact I can't see any of the ucd.ie domain. By IP address there
are no problems. (In other words 'ping XXX.ucd.ie' gets nowhere; 'ping
137.43.XX.XX' works normallly).

If I bring down eth0 at home everything is hunky-dory, and it all just
works. I assume that the problem is connected with the DNS setup linked
to eth0, and when I kill this interface everything defaults to the ppp0
interface on the modem.

Now for the question - I'm very lazy, and resent typing 'ipconfig eth0
down' regularly. Can I set things up either not to bring up eth0 if it
isn't plugged in, or so that this won't interfere with name resolution.

As is obvious I don't really understand how all of this hangs together -
  a pointer to a nice simple tutorial would be welcome also.

Anthony Staines

-- 
Anthony Staines, Lecturer in Epidemiology, Department of Public Health,
   UCD, Earlsfort Terrace, Dublin2, Ireland. http://phm.ucd.ie/
   E-mail :- Anthony.Staines at domain ucd.ie Web :- http://astaines.ucd.ie/
     Work :- + 353 1 716 7345       Fax :- +353 1 716 7407
     Home :- + 353 1 849 1089    Mobile :- +353 1 86 606 9713	


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