[Snort-users] Snort & multi-port ethernet cards

Tom Sevy tsevy at ...1701...
Thu Jun 20 07:54:04 EDT 2002


Running various versions of snort, in the 1.8 range, I've tried to use two
different multi-port ethernet adapters.

One is an HP ANA-6944B/TX (Adaptec OEM'd to HP), 4 x 21140

and

the other is a Znyx ZX346Q, 4 x 21143

Base systems:

1) Compaq Proliant 1850R 2x PIII cpu's, FreeBSD 4.4 & 4.5 versions

2) Compaq Proliant 1600R 2x PIII cpu's, RH Linux 7.3

In the various scenarios I have tried to use these cards, it seems that only
one port at a time will actually return packets.  Verified by running
tcpdump on the different ports (ie., it's not just snort!  the symptoms are
seen as the same when trying to run two instances of tcpdump or two
instances of snort.

It is not external to the snort systems -- If I remove the quad card and
through in distinct nic cards, then all is well.

The problem appears to be that when the same driver is used for multiple
NICS, only one of the NICS will function as necessary for snort.

I would like to find a solution to this problem, as I have a couple of quad
cards laying around, and using these I can have a single box monitoring many
internal lan segments.  Otherwise I have to request additional boxes as
sensors.

Hopefully someone else has seen/observed this, and might have a
fix/work-around/solution....







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