Corelan Cybersecurity Research

Insecure.org has released a new major version of the free, open source “nmap” security scanner. (Don’t just call nmap a port scanner – Thanks to many improvements over the last years, nmap has become an excellent security scanner).

Visit http://nmap.org/5/ for more information about this new version.

Although there are roughly 600 updates in this new version, these are the top 5 improvements in nmap 5 :

• ncat (allows data transfer, redirection and debugging) – (Remember hobbit’s nc ?)
• ndiff scan comparison
• better performance
• improved zenmap GUI (including a real neat feature to visually map the network you have scanned)
• Improvement of nmap scripting engine (nse), reviewed existing scripts and added 32 new scripts.

Download and install the new version, buy/read the book, spread the word, and scan ‘til you drop !

Some of my favorite nmap parameters/scan parameters :

Detecting common stateless firewall misconfigurations : Some people allow incoming connections originated from port 20 (FTP), 53 (DNS) or 500 (IKE) in order to “make things work”. Big mistake. This misconfiguration can allow you to find open ports (and traverse firewalls) by setting one of these ports as source port : use parameter -g

Launch multiple scan types at once (syn scan, os & version detection, traceroute, script) : use parameter -A

Scan all ports : use parameter -p-

Display the reason why a port is in a particular state : –reason

Example :

nmap -P0 -nvv -A -p- -g 20 --reason 

Some other interesting parameters are :

-6 : enabled IPv6 scanning

-sO : IP Protocol scan

-D : try to hide a scan with decoy IP addresses

Finally, a couple of words about script scans : (http://nmap.org/nsedoc/)

–script-updatedb : update the script database

Starting Nmap 5.00 ( http://nmap.org ) at 2009-07-16 21:07 Romance Daylight Time

NSE: Updating rule database.

NSE script database updated successfully.

–script=