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Arp resolution problem

Posted on 2000-04-14
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Last Modified: 2010-04-20
My problem is ... peculiar... So, I have a linux box (actually it's booted off floppies - bootdisk & rootdisk) and when I try to resolve an ip address (for instance I type: ping 195.116.101.80) nothing happens. I have put up a sniffer and I noticed that really weird arp request packets are being sent out, look at this:
eth src: 00:c0:13:14:15:16 (OK - my hw)
eth dst: FF:FF:FF:FF:FF:FF (OK - brdcst)
packet arp request (OK)
sender hw: 00:00:00:00:00:00 (?)
sender ip: 0.0.0.0 (?)
target hw: 00:00:00:00:00:00 (?)
target ip: 0.0.0.0 (?)

what the hell... ???
I usually just bring my interface up with a normal:
ifconfig eth0 195.116.101.1
the "noarp" flag is _not_ set. (even if it was no arp frames would have been sent). I have kernel version 2.2.6, and the distibution is slack 4.0.  Honestly I don't know what the mechanism for resolving arp is (kernel? what syscall?). I have taken a look at /etc/nsswitch.conf - but it seems ok. I have no clue :( The worst thing is, that it was all working fine not long ago...

regards,
Filip

P.S. If I missed any important info, please let me know
PSS: I just realized at other times I get totaly random values like:
sender hw: 05 00 00 00 00 10
sender ip: 0.0.1.0
target hw: 00 00 e4 51 00 00
target ip: 228.97.0.0
I realize that something is messed up big time, if anyone can help, I'll be really glad!
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Question by:Filip_Ruszkowski
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kiffney earned 200 total points
ID: 2717415
So, it's just ping and arp that appear messed up?  Or every other net function (telnet, ftp)?  I assume it's everything.  What does the output of ifconfig say?  What does 'dmesg' say when it gets to your ethernet device?  What happened since the time when everything was working fine?  Is your network cable good?  Is your ethercard good?  (the only way to really tell is swap with known good cables and cards - do the cable first, it's cheapest)?  If this is 10baseT (looks like thick telephone cables, not like coax) is your hub ok?  does it light up at your port when you start the pc?
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Expert Comment

by:arikb
ID: 2718882
Can you post the tcpdump output? You can run it on any of the machines you are testing it with.
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by:Filip_Ruszkowski
ID: 2719303
ehm...
First of all, I got it to work. I figured out the the problem lay on the kernel-bootdisk(kernel: 2.2.6). I tried /bootdisk1.44/net.i on the slackware distro and it worked with the same old rootdisk. I then recompiled the kernel several times (and put it on the bootdisk) and tried to match it to the net.i config file (/kernels/net.i/config). If I took the config straight from net.i it actually didn't compile. I then turned off math emulation and all the exprimental stuff and it did compile, I put on floppy booted, and what? - I got the same arp problem. I then compiled the 2.2.14 kernel (the same options turned on I had before) and it worked fine - so it is really hard to say what wqas going on I tested the problem on 2 different 3com cards and a Realtek which otherwise worked fine with linux.

So, thanx for the feedback, but I got it to work myself - still not knowing what the reason for this behavior was. The points go to kiffney. Well, I'm glad it's working :)
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by:Filip_Ruszkowski
ID: 2719308
as said before, I'm glad it's working.
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