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Snort not seeing IP-traffic, just Ether/Other
From: "Kim.Halavakoski () Crosskey fi" <Kim.Halavakoski () Crosskey fi>
Date: Thu, 18 Apr 2013 18:01:42 +0000

Hello,
I have setup a snort-sensor on a RedHat Linux box with traffic from a
switch span-port feeding eth1 on the box. The traffic contains
vlan-tagged traffic, if that makes any difference.

The problem is that I am just getting some weird multicast / SSAP and
DSAP encapsulated Ethernet frames on that interface on the Linux box,
but when a colleague plugged in his laptop with Windows 7 on the same
port it saw all the traffic that I would like to see, meaning IP-traffic
from the monitored networks.

So Windows 7 sees the traffic, but the Linux box running snort just sees
weird multicast / SSAP / DSAP traffic. tcpdump does not show any IP
traffic either. I know this is probably not a snort-question per se, but
being snort-users list I think some of you guys might have som good
insights to this behaviour, probably easy to fix but I just can't get it
right now :( Any ideas on what I am doing wrong here?


The interface is set in promiscuous mode:

[root () xxxanal01 khalavak]# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:14:5E:2A:34:85
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:3668068 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:628710729 (599.5 MiB)  TX bytes:0 (0.0 b)
          Interrupt:16

Snort sees only Ether and Other traffic:

[root () xxxanal01 khalavak]# snort -i eth1
Running in packet dump mode

        --== Initializing Snort ==--
Initializing Output Plugins!
pcap DAQ configured to passive.
Acquiring network traffic from "eth1".
Decoding Ethernet

        --== Initialization Complete ==--

   ,,_     -*> Snort! <*-
  o"  )~   Version 2.9.4.1 GRE (Build 69)
   ''''    By Martin Roesch & The Snort Team:
http://www.snort.org/snort/snort-team
           Copyright (C) 1998-2013 Sourcefire, Inc., et al.
           Using libpcap version 1.0.0
           Using PCRE version: 7.8 2008-09-05
           Using ZLIB version: 1.2.3

Commencing packet processing (pid=3644)
^C*** Caught Int-Signal
===============================================================================
Run time for packet processing was 7.103551 seconds
Snort processed 1354 packets.
Snort ran for 0 days 0 hours 0 minutes 7 seconds
   Pkts/sec:          193
===============================================================================
Packet I/O Totals:
   Received:         1354
   Analyzed:         1354 (100.000%)
    Dropped:            0 (  0.000%)
   Filtered:            0 (  0.000%)
Outstanding:            0 (  0.000%)
   Injected:            0
===============================================================================
Breakdown by protocol (includes rebuilt packets):
        Eth:         1354 (100.000%)
       VLAN:            0 (  0.000%)
        IP4:            0 (  0.000%)
       Frag:            0 (  0.000%)
       ICMP:            0 (  0.000%)
        UDP:            0 (  0.000%)
        TCP:            0 (  0.000%)
        IP6:            0 (  0.000%)
    IP6 Ext:            0 (  0.000%)
   IP6 Opts:            0 (  0.000%)
      Frag6:            0 (  0.000%)
      ICMP6:            0 (  0.000%)
       UDP6:            0 (  0.000%)
       TCP6:            0 (  0.000%)
     Teredo:            0 (  0.000%)
    ICMP-IP:            0 (  0.000%)
    IP4/IP4:            0 (  0.000%)
    IP4/IP6:            0 (  0.000%)
    IP6/IP4:            0 (  0.000%)
    IP6/IP6:            0 (  0.000%)
        GRE:            0 (  0.000%)
    GRE Eth:            0 (  0.000%)
   GRE VLAN:            0 (  0.000%)
    GRE IP4:            0 (  0.000%)
    GRE IP6:            0 (  0.000%)
GRE IP6 Ext:            0 (  0.000%)
   GRE PPTP:            0 (  0.000%)
    GRE ARP:            0 (  0.000%)
    GRE IPX:            0 (  0.000%)
   GRE Loop:            0 (  0.000%)
       MPLS:            0 (  0.000%)
        ARP:            0 (  0.000%)
        IPX:            0 (  0.000%)
   Eth Loop:            0 (  0.000%)
   Eth Disc:            0 (  0.000%)
   IP4 Disc:            0 (  0.000%)
   IP6 Disc:            0 (  0.000%)
   TCP Disc:            0 (  0.000%)
   UDP Disc:            0 (  0.000%)
  ICMP Disc:            0 (  0.000%)
All Discard:            0 (  0.000%)
      Other:         1354 (100.000%)
Bad Chk Sum:            0 (  0.000%)
    Bad TTL:            0 (  0.000%)
     S5 G 1:            0 (  0.000%)
     S5 G 2:            0 (  0.000%)
      Total:         1354
===============================================================================
Snort exiting

[root () xxxanal01 khalavak]

Same with tcpdump, not seeing any IP-traffic just weird "Unknown SSAP"
and "Null information" packets:

[root () xxxanal01 khalavak]# tcpdump -nn  -i eth1
tcpdump: WARNING: eth1: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
20:55:14.105981 00:10:db:fc:45:00 Unknown SSAP 0x26 > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Command],
length 60
20:55:14.106120 00:50:56:95:45:00 > 00:10:db:fc:40:05 Null Information,
send seq 32, rcv seq 0, Flags [Command], length 60
20:55:14.106840 00:10:db:fc:45:00 Unknown SSAP 0x26 > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Response],
length 52
20:55:14.107173 00:10:db:fc:45:00 Unknown SSAP 0x28 > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Command],
length 191
20:55:14.107275 00:50:56:95:45:00 Unknown SSAP 0x3e > 00:10:db:fc:40:05
Unknown DSAP 0x78 Information, send seq 32, rcv seq 0, Flags [Response],
length 52
20:55:14.108298 00:50:56:95:45:00 Unknown SSAP 0x40 > 00:10:db:fc:40:05
Unknown DSAP 0x78 Information, send seq 32, rcv seq 0, Flags [Command],
length 138
20:55:14.108354 00:50:56:95:45:00 Unknown SSAP 0x40 > 00:10:db:fc:40:05
Unknown DSAP 0x78 Information, send seq 32, rcv seq 0, Flags [Response],
length 58
20:55:14.108423 00:50:56:95:45:00 STP > 00:10:db:fc:40:05 Unknown DSAP
0x78 Information, send seq 32, rcv seq 0, Flags [Command], length 89
20:55:14.109385 00:10:db:fc:45:00 Unknown SSAP 0x28 > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Response],
length 52
20:55:14.109395 00:10:db:fc:45:00 Unknown SSAP 0x2a > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Command],
length 52
20:55:14.109400 00:10:db:fc:45:00 Unknown SSAP 0x2a > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Response],
length 52
20:55:14.109488 00:10:db:fc:45:00 Unknown SSAP 0x2c > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Command],
length 95
20:55:14.109494 00:10:db:fc:45:00 Unknown SSAP 0x2c > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Response],
length 80
20:55:14.109567 00:50:56:95:45:00 STP > 00:10:db:fc:40:05 Unknown DSAP
0x78 Information, send seq 32, rcv seq 0, Flags [Response], length 52
20:55:14.110465 00:50:56:95:45:00 Unknown SSAP 0x44 > 00:10:db:fc:40:05
Unknown DSAP 0x78 Information, send seq 32, rcv seq 0, Flags [Command],
length 1206
20:55:14.110546 00:50:56:95:45:00 Unknown SSAP 0x44 > 00:10:db:fc:40:05
Unknown DSAP 0x78 Information, send seq 32, rcv seq 0, Flags [Response],
length 52
20:55:14.111141 00:10:db:fc:45:00 Unknown SSAP 0x2e > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Command],
length 52
20:55:14.111327 00:10:db:fc:45:00 Unknown SSAP 0x2e > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Response],
length 75
20:55:14.111338 00:10:db:fc:45:00 Unknown SSAP 0x30 > 00:50:56:95:20:66
Unknown DSAP 0x6c Information, send seq 32, rcv seq 0, Flags [Command],
length 52
20:55:14.111542 00:50:56:95:45:00 > 00:10:db:fc:40:05 Null Information,
send seq 32, rcv seq 0, Flags [Command], length 46
20:55:14.111581 00:50:56:95:45:00 > 00:10:db:fc:40:05 Null Information,
send seq 32, rcv seq 0, Flags [Command], length 46
20:55:14.119656 00:50:56:95:45:00 Unknown SSAP 0x44 > 00:50:56:95:20:64
Unknown DSAP 0xb6 Information, send seq 32, rcv seq 0, Flags [Command],
length 240
^C
22 packets captured
22 packets received by filter
0 packets dropped by kernel
[root () xxxanal01 khalavak]#

Best regards,

Kim Halavakoski

PGP S°: 0BFA A910 9AA7 94A5 A323  53F5 4151 4CE4 33BE 35FA
kim.halavakoski () crosskey fi
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