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First time attempting to connect Linux to Windows peer to peer

F

Felecha

Golden Member
I don't have a lot of networking experience and I've used up all that I do have.

This is at my job.

I have a laptop HP N5470 Windows XP SP2, and we have a CPCI "dialer" running Linux RedHat 9, with 2 ethernets, eth0 and eth1 (I'm a rookie at Linux, too). The dialer runs software written for our company by an outside contractor.

Thats the whole network, just those 2 machines.

I set my laptop to 10.0.2.1 with no Gateway or DNS

I set the Linux eth0 to 10.0.2.5, also no gateway or DNS. It's the only card activated

Both 255.255.255.0

I added an entry to the etc/hosts as directed by the contractor
10.0.2.5 dialer

I thought that would be sufficient, but I can't ping either machine from the other. I can ping each machine from itself.

In Windows Network Connections it says "Connected". The amber and green lights on the ethernet ports are on. I am using a crossover cable, manufactured not hand-made, and known to be good.

I don't know where to go further
 
On the Linux box, as root, say "tcpdump" or "tcpdump -i eth0".

The from the Windows box do a "ping 10.0.2.5". Note you ping the IP, not the name

You may or may not see these packets in tcpdump. If you do then the physical connection is OK and you screwed something else up, e.g. you might have firewalling on on the Linux box. If you don't see anything check the physical connection and the Windows setup again.

Again, start testing with IP addresses, not names. Name resolution can be screwed up for other reasons.

Workground don't matter at that level.
 
Oh, and are you sure you have the right card connected?

It is nontrivial to figure out which eth0 or eth1 belongs to which physical card. Take one card out to be sure,
 
The connection is just a direct cat5 cable, laptop port to Linux port. It's a crossover cable.

When I pinged I did it by IP - "ping 10.0.2.5"

And I will try the other port on the Linux when I get to work. On the face of the machine are 2 ports labeled LAN 1 and LAN 2, from the manufacturer (Carlo Gavazzi - it's an industrial rig). I think that when we first got it and did some preliminary setup before sending it out to the Linux developer to build his app for it, I was using LAN 1 as eth0. Then we had it on our company LAN, connected through a hub, and DHCP, and it worked, although at that time too we had to diddle things. Unfortunately I'm a newbie at the company and the guy with the most networking knowledge knows nothing of Linux. And he was out yesterday too.

But since we're going to be using it the way I'm trying to set it up now, I went ahead and hoped my rookie knowledge would suffice.
 
The port on the Linux IS the correct port. I set it up in exactly the same way connected to my desktop at work instead of the laptop. Same IP = 10.0.2.1, etc. The desktop and Linux box CAN ping each other. So there's something on the laptop setup that's not working.

I did the tcpdump thing and it works. Thanks. Always learning.

 
What are you getting when you ping from the laptop? Destination host unreachable, Timing out, or something else? You might try the winsock2 fix if your laptop is on the internet much or if you have run an antispyware app. They can corrupt winsock, which basically leaves your NIC without connectivity no matter what you do. Just a thought.
 
I do run Ad-Aware every now and then.

Ping gets me a timeout, not host unreachable.

I just now put the laptop back on the regular network here, and it connected to Yahoo right away. So if a Winsock corruption thing is happening I couldn't do ANYTHING?
 
Well, there's learning in here somewhere.

A coworker suggested setting up a hub and conneccting both to that with straigt-through cables. THAT WORKS.

So a direct cross-over between the laptop and the Linux does not work and connecting through a hub does work ....And a direct crossover from my desktop to the Linux does work ... ???

 
Originally posted by: Felecha
Well, there's learning in here somewhere.

A coworker suggested setting up a hub and conneccting both to that with straigt-through cables. THAT WORKS.

So a direct cross-over between the laptop and the Linux does not work and connecting through a hub does work ....And a direct crossover from my desktop to the Linux does work ... ???
Click to expand...

Ahhhh!

The problem here is that the auto-negotiation, the discovery of the speed for the cards, failed. The cards arrived at different ideas whether you have 10 or 100 mbit, full-duplex or half etc.

You need both good cards and good drivers for it to work in that situation.

If you connect to a hub it is easier because the port isn't such a moving target as the other ethernet card can be which might try autonegotiation at the same time so that they present moving targets to each other.
 
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