ISC reader Keith reports a "strange packet" on his network. He gets the following alert 9/28/2010 2:09 PM : C4K_L2MAN-6-INVALIDSOURCEADDRESSPACKET 272: Sep 28 19:09:41: %C4K_L2MAN-6-INVALIDSOURCEADDRESSPACKET: (Suppressed 5 times)Packet received with invalid source MAC address (45:42:55:47:3D:57) on port Po1 in vlan 24 and the following packet to go with it: 0000 3d 3d 4b 56 3d 44 45 42 55 47 3d 57 26 4c 3d 3d No surprise really that this packet is "illegal". When parsed into plain ASCII, it reads ==KV=DEBUG=W&L== Has anyone seen this before and might know what sort of device could be burping out these non-IP packets directly onto the VLAN? |
Daniel 385 Posts ISC Handler Sep 28th 2010 |
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Sep 28th 2010 1 decade ago |
a two year old post on cisco forums yields little info on a similar message:
https://supportforums.cisco.com/thread/147193?tstart=0&viewcondensed |
Alan 57 Posts |
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Sep 29th 2010 1 decade ago |
Yep that mac showed up there.
==KV=DEBUG=W&L== is that related to KV Ladder Building software for PCL? You may have something interesting... |
drStrangeP0rk 11 Posts |
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Sep 29th 2010 1 decade ago |
Sorry PLC?
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drStrangeP0rk 11 Posts |
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Sep 29th 2010 1 decade ago |
Can't comment anything on this particular packet but the log message is pretty well known here from our Catalyst 4500 machines for some years.
The posting gave me a hint to analyse the "MAC-adresses" seen here. Some obviously ascii highlights: 21:21:21:21:23:3C: !!!!#< 21:23:46:75:33:21: !#Fu3! 2D:61:6C:69:76:65: -alive 3D:30:2E:31:0D:0A: =0.1\r\n 41:25:37:43:70:6F: A%7Cpo 47:3D:31:35:6D:76: G=15mv 57:25:33:44:61:74: W%3Dat 61:67:65:3A:20:64: age: d 63:6D:64:2F:65:76: cmd/ev 65:0D:0A:43:6F:6F: e\r\nCoo 65:3A:20:31:31:35: e: 115 65:63:6B:6F:29:20: ecko) 69:72:65:66:6F:78: irefox 69:76:65:3A:20:31: ive: 1 6D:2F:64:65:2E:68: m/de.h 6F:6E:74:65:6E:74: ontent 73:3D:64:65:3A:35: s=de:5 My assumption: a somehow broken IP-stack on the endhost, not a particular application, maybe a flaw in the NIC driver. It looks like "fragments" of data with the network header stripped. |
Jens 42 Posts |
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Sep 29th 2010 1 decade ago |
is the source and destination MAC addr. the same ?
if yes, i recall our IPS blocked it on a CISCO L3 switch, and noted that this is an impossible packet, cause is a DoS tool called LAND.C, search for it you should have a lead form there. |
Jens 8 Posts |
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Sep 29th 2010 1 decade ago |
Thanks for the help, everyone. I've received some pretty good leads. Hopefully, they will help determine a resolution. I'll keep you posted.
I am seeing this packet on a Cat4500. The source and destination MACs are different. Source - 45:42:55:47:3D:57 Destination - 3d:3d:4b:56:3d:44 |
Keith 1 Posts |
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Sep 29th 2010 1 decade ago |
The leading 45: makes it a multicast address, suspect this is some sort of discovery protocol.
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Jeff 3 Posts |
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Sep 29th 2010 1 decade ago |
<pre>
45:42:55:47:3D:57: EBUG=W 3d:3d:4b:56:3d:44: ==KV=D </pre> For shorthand analysis: <pre> echo $MAC | sed 's/(//' | sed 's/)//' | awk -F: '{printf "%s: %c%c%c%c%c%c\n", $0, strtonum("0x"$1), strtonum("0x"$2), strtonum("0x"$3), strtonum("0x"$4), strtonum("0x"$5), strtonum("0x"$6)}' </pre> |
Jens 42 Posts |
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Sep 30th 2010 1 decade ago |
We have the same on two switches. We have traced it back to a Tandberg. I am continually looking to identify the mechanics, but I have been told that it is innocuous. Not sure I am buying that just yet because I don't know exactly why it is occurring and it does not appear to happen with any of our other Tandbergs.
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Jens 1 Posts |
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Sep 30th 2010 1 decade ago |
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