Nmap(“Network Mapper”) is an open source tool for network exploration and security auditing. It was designed to rapidly scan large networks,although it works fine against single hosts. Nmap (or Network Mapper) is a powerful, complete, open-source tool for network exploration and port scanning.

After a long wait from 1997 , here is the update of NMAP , it's bigger and better this time , here is changelog of NMAP 5.0 : Changelog

How to compile from source :

# Get the source
$ wget http://nmap.org/dist/nmap-5.00.tar.bz2

# Extract the source
$ tar jxvf nmap-5.00.tar.bz2 ; cd nmap-5.00/

# As a root
$ chmod 777 *
$ ./configure
$ make
$ make install

Thats it , nmap 5.0 is up and running. Do read the changelog and manuals before you mess around.