[Techtalk] network failure help!

[Devdas Bhagat]

On 13/05/04 19:01 +0100, Telsa Gwynne wrote:
<snip>
> I once took my little laptop somewhere else, plugged into an
> office network, and was told "We use DHCP here". Unusually, I
> had rarely used DHCP. Everyone else uses the damn thing, but I
> haven't a clue about it still. I had a resolv.conf and a hostname 
> that worked for me at home. So I used "pump" (a RH app of the time:
> I am not sure it's still the default) to "sort all the DHCP stuff out", 
Its not the default on RH now. It is still on Debian though, IIRC.

> admired the now-sorted network, stayed for ages, and went home.
> 
> By the time I plugged the laptop back in at home, I had 
> completely forgotten about this little jaunt. As you do.
> Ahem. And the wretched thing would _not_ talk to the net. I 
ping ip.of.gate.way <=== first debugging test.
If that works, then you have a network connection. If it doesn't, then
bother about lower level stuff like hardware.
Then ping by name. This test has issues with providers blocking ICMP due
to crap like blaster.

<snip>
> Eventually I realised that it was still trying to look up 
> every hostname on the nameserver in that office. Behind the
> office firewall. Which was saying "bog off". 
Ah! Yet another reason to actually see what is on the network.
tcpdump is your friend. It has saved me hours of debugging netwokr
issues.

<snip>
> So if your laptop has been travelling with you, I would 
> check what network it thinks it is connecting to. :) 
In this case, there was a physical connection, but no data link layer
connection.

Devdas Bhagat