Ethereal and ethereal do store the packets, but in a ring buffer file for a
limited number of seconds. This limits the size of the log file but does allow
you to go back up to the beginning of the buffer to get some previous history.
Whether it is long enough to capture all traffic of interest is a possible
problem.
-----Original Message-----
From: Murtland, Jerry [mailto:MurtlandJ@Grangeinsurance.com]
Sent: Monday, September 13, 2004 12:52 PM
To: 'Alex Butcher, ISC/ISYS'; David W. Goodrum; Raj Malhotra
Cc: focus-ids@securityfocus.com
Subject: RE: session logging IDS
Hmmmm, I would like verification that either Cisco or Intrushield (or any
other IDS/IPS) can actually capture an entire session from beginning to
end, when the alert was triggered somewhere in the middle, and that they
can do it all the time.
From the way that you are stating it, it cannot be done. The IDS's sniffer
must be manually started and cannot go back to the beginning of an attack to
find out what happened. This can only be done if the sniffer were enabled
100% of the time, and we all know that you basically cannot do this due to
logging capacity.
I'm more interested in tethereal and how you say it can go back per the
'tag' keyword. I'd have to try it out to see how this works, but are you
saying you can go back and review packets previous from when the sniffer was
enabled? I can't see how this could occur since packets are not stored.
Jerry J. Murtland
-----Original Message-----
From: Alex Butcher, ISC/ISYS [mailto:Alex.Butcher@bristol.ac.uk]
Sent: Thursday, September 02, 2004 4:04 AM
To: David W. Goodrum; Raj Malhotra
Cc: focus-ids@securityfocus.com
Subject: Re: session logging IDS
--On 30 August 2004 18:04 -0400 "David W. Goodrum" <dgoodrum@nfr.com> wrote:
Hmmmm, I would like verification that either Cisco or Intrushield (or any
other IDS/IPS) can actually capture an entire session from beginning to
end, when the alert was triggered somewhere in the middle, and that they
can do it all the time.
That would certainly be a new feature for Cisco's offering since the last
time I worked with it (Mid-2002).
The only other things that I've seen that are relevant are Niksun's NetVCR
and Snort/sourcefire. At the moment, out of the box, Snort can only capture
subsequent packets in a session or from a source host *after* the
alert-triggering packet (using the 'tag' keyword). I'm currently extending
ACID and FLoP to allow pcap files of tagged alerts to be downloaded from
ACID for analysis using Ethereal or other tools.
The other thing I thought of, after being inspired by Niksun's product, was
to arrange for tethereal to dump to a pair of files (i.e. a double buffer),
switching every n minutes. It would then be possible to arrange for an IDS
to send a signal to tethereal (or rather, some controlling process) when it
generated an interesting alert, telling tethereal to preserve the previous
dump file, and continue logging to the current one until further notice,
giving you upto at least n minutes of reverse 'time travel'.
-dave
David W. Goodrum
Best Regards,
Alex.
--
Alex Butcher: Security & Integrity, Personal Computer Systems Group
Information Systems and Computing GPG Key ID: F9B27DC9
GPG Fingerprint: D62A DD83 A0B8 D174 49C4 2849 832D 6C72 F9B2 7DC9
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