I like to run nmap in phases to balance the speed and accuracy. For
example, run only a SYN scan (-sS) for the 1st phase then follow up with the
service detection, OS detection, etc., scan after you discover the list of
'live' devices and open ports. In my experience those extra options can add
lots of time (especially when scanning large blocks, like a /16) and I like
to obtain the open port list as soon as possible to feed others tools (amap,
nessus, etc.).
I also always try to add options to account for current latency conditions,
bandwidth availability, and the specs of the server running nmap. Things
like: min_hostgroup, min_parallelism, min-rtt-timeout, --max-retries.
An initial scan I may run with high latency (400ms rtt), lots of bandwidth,
and a good server is:
nmap -vv -sS -P0 -p 1-65535 -n --min_hostgroup 100 --max_retries 3
--max_rtt_timeout 1250 --min_parallelism 100 -oA <output_file> <net_block>
For a follow up:
nmap -vv -p <open_port_list> -sT -A -P0 -n --min_hostgroup 100
--max_rtt_timeout 1250 --min_parallelism 100 -oA <output_file> -iL
liveIPList
Another observation: I frequently find additional open ports when executing
multiple scans of the same blocks at different times. For whatever reason
(e.g. network hiccup, target load, server load) it helps to run repeated
scans if you want to improve/have greater confidence in your results.
Running a few SYN services scans in addition to your normal scans at
different times may reveal a few more open ports.
Tate Hansen
ClearNet Security
-----Original Message-----
From: Doug Fox [mailto:dfox168@hotmail.com]
Sent: Thursday, March 23, 2006 8:07 AM
To: pen-test@securityfocus.com
Subject: NMAP Switches, -sS, -sT, etc.
If I may, I like to poll the list what are your favorite switches when using
NMAP to conduct "intensive/comprehensive" security testing.
I have been using
NMAP -vv -A -sS -O -p1-65535 -P0 -oX target.xml www.xxx.yyy.zzz.
I find I got more information using -sS than -sT and requires short time.
Any suggestions/comments are appreciated.
Thanks,
DF
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