RE: [Sheflug] SuSE 7.3 Network Problems

["Alistair Williamson" <xxxxx [at] xxxxxxxxxxxxxx>]

Hi Alex,

Thanks for all of that.

I have tried a different patch cable (new) a different port on the hub, I
have removed all other machines from the hub (except my laptop - now running
w2k), I have also tried a direct connection via crossover cable between the
machines (I know it's a good cable - I'm using it now to the router!).

I set up the tcpdump as you suggested, when I connected my laptop to the
network, there was a fair bit of activity - both the activity lights on the
hub were flashing away and the tcpdump recorded:
11:38:40.016517 192.168.0.1.32768 > 192.168.0.295.137:
>>>NBT UDP PACKET(137): QUERY;REQUEST;BROADCAST (DF)

The same lines appear several times - with just the time stamp being
different. I thought that meant there was some network activity, however
when I tried to ping (using -n) the laptop, tcpdump recorded:

11:39:19.136704 arp who-has 192.168.0.5 tell 192.168.0.1

As my 4 year old daughter says when her mum is angry "Man - it's not looking
good!"


Any other ideas?

Cheers,

Alistair
> -----Original Message-----
> From: shef-lug-admin [at] list.sheflug.org.uk
> [mailto:shef-lug-admin [at] list.sheflug.org.uk]On Behalf Of Alex Hudson
> Sent: 15 December 2001 11:27
> To: Sheffield LUG
> Subject: RE: [Sheflug] SuSE 7.3 Network Problems
>
>
> On Sat, 2001-12-15 at 11:05, Alistair Williamson wrote:
> > I am also running SuSE 7.3 on my laptop - when it's connected to the
> > network - it can exchange pings with all the other machines (except the
> > server!)
>
> Okay, it's not firewall.
>
> First, let's rule out hardware. You've tried different cards, so it's
> not the card that's the problem. Swap cables with a known working node
> on your network (assuming you have more than one other PC on this
> network), and try with that. If it still doesn't work using the
> connection that works for other machines, then it's not hardware at all.
> If it does work, it's either a dodgy cable or a dodgy port on your hub.
>
> In terms of software, there are a number of things it could be. The best
> thing to do is make use of virtual terminals - I would run (as root)
> 'tcpdump -i eth0 -n' on a terminal and leave it running while you test
> the network on a different terminal - this way, you're capturing all
> your network stuff which may help sort out why this isn't working.
>
> Try pinging again while capturing data. You should see a line like this:
>
> 11:18:28.780776 192.168.0.1 > 192.168.0.10: icmp: echo request (DF)
> 11:18:28.780888 192.168.0.10 > 192.168.0.1: icmp: echo reply
>
> (That's my gateway machine pinging my laptop). Ignore the numbers at the
> start of the line. What you're interested in is the other stuff:
> generally, it's:
>
> 	IP address A > IP address B: traffic
>
> So the machine at 'a' is talking to 'b', tcpdump will also tell you
> roughly what they're saying. If you see something which looks like a
> five-tuple IP address (i.e., something like 192.168.0.10.80) the last
> number is the port.
>
> Now, if your network _really_ isn't working, all you're going to see is
> something like:
>
> 11:22:40.598992 arp who-has 192.168.0.10 tell 192.168.0.1
>
> .. with no responses. If this is all you get, then something's really
> screwed - I would guess hardware, but hopefully you've ruled this out,
> so this would probably indicate drivers (but this would be _very_
> surprising). If you see anything more than just this, then your network
> is running at some level.
>
> Things to try:
>
> 	ping -n (some valid ip)   - you know what this does ;)
> 	arp 			  - the output of this would be useful;
> 				    it should be the MACs of the other
> 				    network machines.
>
> Make sure you're using the -n option on ping. Make sure you're not using
> the same ip address elsewhere (always worth checking ;). Make sure the
> network configuration (subnets, etc.) is the same on the other machines.
>
> Cheers,
>
> Alex.
>
>
> ___________________________________________________________________
>
> Sheffield Linux User's Group - http://www.sheflug.co.uk .
> To unsubscribe from this list send mail to
> shef-lug-request [at] list.sheflug.org.uk with the word
> "unsubscribe" in the body of the message.
>
>   GNU the choice of a complete generation.
>

___________________________________________________________________

Sheffield Linux User's Group - http://www.sheflug.co.uk . 
To unsubscribe from this list send mail to 
shef-lug-request@list.sheflug.org.uk with the word
"unsubscribe" in the body of the message. 

  GNU the choice of a complete generation.