[WBEL-users] Network Connectivity on WBEL 4

[Dan Herrstrom]

> 
> Do the lights blink as when you do the ping?  I know it's silly, but
> that's actually how I figured out my problems with my bad switch
> (the lights blinked on the port that the packet came out, but didn't
> on the port the packet should have been received on).  That will at
> least tell you if the packet is leaving the Linux machine.  If it
> is, does the Window's machine blink immediatly afterwards?

Yes the lights all blink as they should. This is not a phyiscal layer issue.

> 
> If you can control the network enough (ensure that it's traffic
> free).  Take the Workstation run the whatever windows utility that
> will show you how many packets have been sent and received (one of
> the "LAN Connection" windows shows it).  Record the TX and RX
> counters on both machines.  Then run ping so it sends only one
> packet.  Now examine all of the counters again.  Which ones
> changed should help figure out what activity is actually happening.
> I'd try doing that, and running ping in both directions (from
> Windows to Linux, and from Linux to Windows).

On the Windows box the bytes sent goes up but not the bytes received.

> Curious.  It says stopped, even after you started it...  That's
> weird.  What's iptables -L say?  That'll print out the actual rules,
> and more specifically the default policy.
> 

I'm guessing its because I set the firewall to 'disabled' during
install. (I'm not really worried about it right now as the box has no
access to/from the internet anyway.)

[root at mainframe ~]# iptables -L
Chain INPUT (policy ACCEPT)
target          prot  opt   source                        destination

Chain FORWARD (policy ACCEPT)
target         prot   opt   source                       destination

Chain OUTPUT (policy ACCEPT)
target         prot   opt   source                       destination
[root at mainframe ~]#

> > > Finally, you might be looking in all the wrong places.  I've have
> > > several times where "ping" didn't work not because the machine I
> > > just setup was configured wrong.  The packets got off the new
> > > machine and to the destination machine just fine.  However, the
> > > existing machines couldn't route packets back, because it was
> > > missing a route or something else was misconfigured.  So be aware of
> > > that.  That handiest way to see that is to run a packet sniffer on
> > > the destination.  The poor man's way of doing that is to watch the
> > > blinky lights on the switches.

I did a packet capture with Ethereal and the windows machine sends out
ARP requests when i attempt to ping from it but never receives
responses. If I attempt to ping it from the linux box it receives ARP
requests from the linux box and sends the reply but the linux box
seems to ignore it and continues to do ARP requests never sending a
ICMP packet.

> Just to be anal retentive, when you used the laptop, did you pull
> the wires from one of the mainframe NIC's?  In theory you could be
> dealing with bad ports on the switch, or bad cabling.  Grabbing
> another cable, or using another port on the switch wouldn't test
> that.  I'd try of the cables from mainframe leaving it on the same
> port on the NIC.  Then I'd try using the IP from the mainframe on
> the Window's machine.

Yes i used one of the ones from the machine in question 

(OT: It's not really a mainframe the name is just a reference to a
cartoon I watched as a kid).

> Hmmm, could it be the "SELinux" stuff.  I don't know if that has
> anything to do with networking (my co-worker setup all of our
> CentOS4/WBEL4 machines).  I know it's broken some things on some
> machines we've had around.  Anything interesting in dmesg?  Does the
> dmesg output change when you run ping?

Nothing changes. I only guessed maybe SELinux was involved since on a
previous install I tried upgrading to Fedora Core 3 (which has SELinux
enabled by default I belive) from Core 2 it broke at least SSH access
to the machine. I've completely reinstalled WBEL with
SELinux set to disabled and no change.

> I'm pretty much out of suggestions after that... Good luck.

Thanks for your help.