Subtle and peculiar network hardware problem

[david at thekramers.net (David Kramer)]

steve at horne.homelinux.net wrote, On 08/03/2004 10:29 PM:
> 
> I recently bought a laptop on ebay (long irrelevant story) which
> has a problem I've neber seen before.  When I set up the built-in ethernet,
> everything seems to go fine.  Works in Knoppix (first time), and in xp (after n reboots, for large n -- maybe a clue?)  
> 
> "seems" is the key word.  I can ping out, dns lookups work,
> at least in knoppix.  (I think pings worked in xp too.)
> 
> 
> But I can't use ssh, or a browser.  Even in knoppix.

You don't say what happens when you try.

Diagnostics:
tail -f /var/log/messages as you try your browser
tcpdump  -i whatevertheethernetdeviceis as you try your browser
iptables -L -n | more to see any firewall rules that might be blocking

My first-cut guess is that you have a firewall rule blocking TCP traffic but 
not UDP traffic, either on the laptop itself, or whatever you use between the 
internet and your intranet.  Try assigning it a very different IP address, too.

> When I plug a network card into the pcmcia slot, the pcmcia
> card works fine in all respects in both knoppix and xp.

Since it will have a different device name, it may not be blocked by the firewall.

> The question -- is it possible that the hardware is somehow broken,
> so that pings work, and dns lookups work, but 
> nothing else???

I really can't imagine that's the case.  Once you have link-level 
connectivity, the hardware doesn't care what protocol runs over it,


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