RE: Questions: nmap, nessus unreliability, setting up a packet capture box, using Impacket

["Jerry Shenk" <jshenk () decommunications com>]

If you use SHADOW, you can easily modify it to grab the full snaplen of
the packets.  To do this, modify the tcpdump command in the std.ph (or
whatever the site is named) file in the sensor directory.  Here's a
modification I made for special purpose sensor I installed a few months
ago to deal with a specific problem user.

$LOGPROG  = "/usr/sbin/tcpdump -s 4000";

BTW, some tcpdumps with use -s 0 to specify to grab the entire payload
of the packet but that doesn't work for all of them - just wanted to
head off any flames in advance....but this isn't a terribly flamey
group;)

-----Original Message-----
From: Dan Goldberg [mailto:dan () madjic net] 
Sent: Friday, April 23, 2004 2:12 PM
To: Paul Johnston; pen-test () securityfocus com
Subject: Re: Questions: nmap, nessus unreliability, setting up a packet
capture box, using Impacket


> 1) How reliable have people here found nmap and nessus to be?
> Anything that can be done about this?

Paul,
        I have had very good luck with Nmap. It helps to know something 
about the path to the host(s) your are interested in. You will get 
different results and responses depending on whether there are 
firewalls or packet filters between the scanner and target. (Sorry I 
know this is obvious).
        In addition I always capture a packet trace of any scan I
perform 
create an audit trail of the scan and see anything that Nmap fails to 
report on as I would expect.
        I also tend to break large scans in to smaller chunks. Rather
than 
scanning -p 1-65535 on a host  I will script out a few chunks at a 
time usually getting well known or expected ports first. This is 
mostly to keep from bogging down the scanner (especially if the 
scanner is a windows box).

> 2) I'm looking at setting up a box to capture all traffic on our
> scanning network. Does anyone have thoughts on doing this, based on
> their operational experiences?

I would think that a system like Shadow 
http://www.nswc.navy.mil/ISSEC/CID/ would help here or else Snort in 
Logging mode.
        I have used Shadow to capture large amounts of traffic on a 24
hour 
basis and the front end is excellent for reviewing headers. It does 
collect IIRC the 1st 68 bytes though not entire packets.

> 3) Using Core Impact's Impacket library,
I have never used this.

Hope this helps.
-- 
dan () madjic net
-- 

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Ethical Hacking at the InfoSec Institute. Mention this ad and get $545 off
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to facilitate one-on-one interaction with one of our expert instructors.
Attend a course taught by an expert instructor with years of in-the-field
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