Snort mailing list archives

RE: A Couple of Questions


From: twig les <twigles () yahoo com>
Date: Fri, 31 Jan 2003 11:50:06 -0800 (PST)

I have caught an errant NIC before (bad driver) using
the eval of sniffer pro.  All I noticed was that one
workstation was blabbing ten times more than the
others and the lady sitting at the station was in
finance and had no idea what a driver was.

As for Snort detecting this, the NIC would have to
break a rule and send bad packets like same
source/dest or something.  I have seen our glorious
firewall vendor do this many times, and when
tcpdumping the packets to see wth is going on the
packets had bad checksums and were being dropped at
the switch interface.  


Does anyone have an answer to my 2nd question?

Has anyone written a rule for, or been able to use
Snort to detect signs
of a failing NIC?  I don't know the terminology
off-hand but a dying NIC
may start to "yell" at the network, causing the
surrounding NICs to
spend a lot of time dropping packets not
specifically destined for them
(they still have to look at the packets to know to
drop them).  The NIC
on the offending machine still appears to work
somewhat but performance
on the machine is very poor.  Also, the surrounding
network (whatever is
in the same collision domain) will suffer.  Incoming
tech calls will be
something like "Are things running kind of slow
today?".  I've dealt
with this sort of thing in the past and have luckily
come across the
failing NIC by chance.  I'd like to be able to
pinpoint this sort of
thing more easily using Snort if at all possible. 
Please let me know if
you're aware of any such rule.

Thanks again, Lars.


-----Original Message-----
From: Morgan R. Elmore
Sent: Thursday, January 30, 2003 3:20 PM
To: Lars Borland; snort-users () lists sourceforge net
Subject: RE: [Snort-users] A Couple of Questions


Lars,

It sounds to me like some bogus sensor information
was placed into the
db while your sensor was messed up.  I'm assuming
that you are using
MySQL?  I'm going off of the top of my head, so
these commands might not
be entirely accurate...
Log into MySQL from a command prompt (DOS box):
    mysql -u (username) -p
    type in the password
    connect db (db=database name, should be snort or
something like it)
    select * from sensor;    (don't forget the
semicolon at the end of
the line)
    you should see 4 separate sensors....
    delete from sensor where sid=(the sid of the
bogus sensor)

After that, ACID should only show one sensor.



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