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Old 06-29-2016, 03:59 AM   #1
berndbausch
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How to get rid of SNAP packets in tcpdump trace?


I am running tcpdump and get packets of this sort roughly once a second:
Code:
22:43:05.589112 fc:15:b4:fa:2c:d3 > 01:14:c2:44:1e:cc, 802.3, length 80: LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: oui Unknown (0x0014c2), pid Unknown (0x0001): Unnumbered, ui, Flags [Command], length 66
They pollute my output and make it hard to read. I have been unable to find a way to filter them out.
What are they for?
How to filter them out?

Thanks much!
 
Old 06-30-2016, 05:04 AM   #2
jnihil
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That dst MAC is a loop-detection multicast packet sent by HP's virtualconnect.
I can't seem to find a way to match on SNAP headers, but you could do the following to filter out such packets by filtering on the dst MAC:

tcpdump -i <inerface> ether src not 01:14:c2:44:1e:cc
 
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Old 06-30-2016, 10:37 AM   #3
berndbausch
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Quote:
Originally Posted by jnihil View Post
That dst MAC is a loop-detection multicast packet sent by HP's virtualconnect.
I can't seem to find a way to match on SNAP headers, but you could do the following to filter out such packets by filtering on the dst MAC:

tcpdump -i <inerface> ether src not 01:14:c2:44:1e:cc
VirtualConnect makes sense - this happens inside an HPE Blades enclosure.
Filtering for this particular MAC address looks like a good solution. Thanks!
 
  


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