Well, just when I was working on my e-book on nmap (Announced), Fyodor decided to release a new version of his popular hacking tool. Which mean my book will be postponed even further. But on the upside it will contain a huge amount of new information and functions not available before, including 2nd generation OS detection.

Here is a list of Major new option in nmap 4.50:

• Zenmap graphical front-end and results viewer: Zenmap is a cross-platform (tested on Linux, Windows, Mac OS X) GUI which supports all Nmap options. It allows easier browsing, searching, sorting, and saving of Nmap results.
• 2nd Generation OS Detection: The new 2nd generation system incorporates everything we learned during those years and has proven itself more effective and accurate. The new database has 1,085 signatures, ranging from the 2Wire 11701HG wireless ADSL modem to the ZyXEL ZyWall 2 Plus firewall. In addition to more than 500 general purpose OS fingerprints, it contains 94 switches, 92 printers, 81 WAPs, 63 broadband routers, 31 firewalls, 19 VoIP phones, 16 webcams, 8 cell phones, and more. We currently only have fingerprints for 1 ATM machine and 2 game consoles. The new system is extensively documented.
• Nmap Scripting Engine: The Nmap Scripting Engine helps change that by allowing users to write (and share) simple scripts to automate a wide variety of networking tasks. Those scripts are then executed in parallel with the speed and efficiency you expect from Nmap.
• Performance and accuracy improvements: We have made a number of improvements to enhance Nmap performance and accuracy. Not only were the host discovery and OS detection systems completely replaced, but we improved the port scanning algorithms in the process.
• Version detection enhancements: The Nmap version detection system has continued to flourish. It allows Nmap to determine the service listening on a port using protocol communication rather than making assumptions based on port number.
• Host discovery (ping scanning) system rewritten: The old host discovery system (massping()) was removed and the primary port scanning engine (ultra_scan()) augmented to support host discovery. The new system is more accurate, and in some cases faster.
• Bug fixes: There were hundreds of bug and portability fixes to keep Nmap working on all the popular operating systems and prevent crashes or other misbehavior. These are all detailed in the Nmap Changelog.
• Political correctness: To cultivate a professional image, we long ago capitalized all references to God in error message text and also reworded all instances of “fucked up” to “borked”.
• –reason explains why a port is open/closed/filtered: The new –reason option adds a column to the Nmap port state table which explains why Nmap assigned a port status. For example, a port could be listed as “filtered” because no response was received, or because an ICMP network unreachable message was received. With –reason, you can find out which was the case without digging through –packet-trace logs.
• Advanced traceroute support: Nmap now offers a –traceroute option which uses Nmap data to determine which sort of packets are most likely to slip through the target network and produce useful results.
• Public Subversion (SVN) repository: While some formerly open source programs are becomming more proprietary, Nmap continues to open up with a public Subversion (SVN) source code repository. All users can now check out the latest Nmap in-development code, and several developers now have commit access so sending patches to Fyodor is no longer a bottleneck.
• TCP and IP Options: Nmap now supports IP options with the new –ip-options flag. You can specify any options in hex, or use “R” (record route), “T” (record timestamp), “U” (record route & timestamp), “S [route]” (strict source route), or “L [route]” (loose source route).

For a list of more options and detailed changelog and information about the new version of Nmap, visit the site announcement page: http://insecure.org/stf/Nmap-4.50-Release.html