Majek's technical blog: Pcap support for Nmap Script Engine

Some time ago I wrote nse-pcap patch for Nmap that adds some libpcap features to Diman's NSE. Today I ported changes to current Nmap. It's definitely time to check if the code is worth time I spent on it!

I think that pcap support one of the most promising features in NSE. It gives "new experience" to advanced programmers. It also introduces easy to use and powerful way of distributing received packets to registered Lua NSE threads. I think it is very nice way of programming pcap applications. Basically it's based on callbacks from pcap, rather than iterating over sequence of pcap results.

Good example of nse-pcap power can give my implemetation of Lcamtuf's p0f SYN+ACK scan.

Try out installation of nse-pcap.

$ svn co --username=guest --password= svn://svn.insecure.org/nmap-exp/soc07/nmap nmap
$ cd nmap
$ wget http://ai.pjwstk.edu.pl/~majek/private/nmap/nse-pcap/nmap-soc07-5184-ncap-try2B2-with-whitespace.diff
$ cat nmap-soc07-5184-ncap-try2B2-with-whitespace.diff|patch -p1
$ ./configure --without-nmapfe && make

And play with the power of p0f.nse script:

$ sudo ./nmap -n -sT -PS80 -p21,22,53,80,443 --script=p0f.nse www.cisco.com

Starting Nmap 4.22SOC1 ( http://insecure.org ) at 2007-07-12 00:04 CEST
Interesting ports on 198.133.219.25:
PORT    STATE    SERVICE
21/tcp  open     ftp
|_ p0f signature: UNKNOWN [65500:61:1:64:M1436,N,N,S,N,W0,N,N,T:AT:?:?] (link: IPSec/GRE, up: 1446 hrs, ipid:54702)
22/tcp  filtered ssh
53/tcp  filtered domain
80/tcp  open     http
|_ p0f signature: UNKNOWN [8192:238:0:44:M1460:A:?:?] (link: ethernet/modem, up: disabled, fill:4008, ipid:1)
443/tcp open     https
|_ p0f signature: UNKNOWN [8192:238:0:44:M1460:A:?:?] (link: ethernet/modem, up: disabled, fill:f8ef, ipid:10)

From this information I can see at least source NAT. And next try:

$ sudo ./nmap -n -sT -p21,22,53,80,443 --script=p0f.nse www.orkut.com

Starting Nmap 4.22SOC1 ( http://insecure.org ) at 2007-07-12 00:04 CEST
Interesting ports on 209.85.141.85:
PORT    STATE    SERVICE
21/tcp  open     ftp
|_ p0f signature: UNKNOWN [65500:61:1:64:M1436,N,N,S,N,W0,N,N,T:AT:?:?] (link: IPSec/GRE, up: 7282 hrs, ipid:30587)
22/tcp  filtered ssh
53/tcp  filtered domain
80/tcp  open     http
|_ p0f signature: UNKNOWN [8190:235:0:44:M1400:A:?:?] (link: sometimes DSL (2), up: disabled, fill:0f2d, ipid:28096)
443/tcp closed   https

I'm waiting for feedback or bug reports!

UPDATE #1:
Okay. I'm so enthusiastic about this project, because I wrote it. But there also some other promising features in nmap, like Swen's Web application detection.

UPDATE #2:
Some usefull links: