The top 6 improvements in Nmap 6 are:
1. NSE enhanced
The Nmap Scripting Engine (NSE) has exploded in popularity and capabilities. This modular system allows users to automate a wide variety of networking tasks, from querying network applications for configuration information to vulnerability detection and advanced host discovery. The script count has grown from 59 in Nmap 5 to 348 in Nmap 6, and all of them are documented and categorized. The underlying NSE infrastructure has improved dramatically as well.
2. Better Web scanning
When Nmap was first released in 1997, most of the network services offered by a server listened on individual TCP or UDP ports and could be found with a simple port scan. Now, applications are just as commonly accessed via URL path instead, all sharing a web server listening on a single port. Nmap now includes many techniques for enumerating those applications, as well as performing a wide variety of other HTTP tasks, from web site spidering to brute force authentication cracking. Technologies such as SSL encryption, HTTP pipelining, and caching mechanisms are well supported.
3. Full IPv6 support
Given the exhaustion of available IPv4 addresses, the Internet community is trying to move to IPv6. Nmap version 6 contains full support for IP version 6. And it is released just in time for the World IPv6 Launch.
Nmap's developers have created a new IPv6 OS detection system, advanced host discovery, raw-packet IPv6 port scanning, and many NSE scripts for IPv6-related protocols. It's easy to use too—just specify the -6 argument along with IPv6 target IP addresses or DNS records.
4. New Nping Tool
The newest member of the Nmap suite of networking and security tools is Nping, an open source tool for network packet generation, response analysis and response time measurement. Nping can generate network packets for a wide range of protocols, allowing full control over protocol headers. While Nping can be used as a simple ping utility to detect active hosts, it can also be used as a raw packet generator for network stack stress testing, ARP poisoning, Denial of Service attacks, route tracing, etc. Nping's novel echo mode lets users see how packets change in transit between the source and destination hosts. That's a great way to understand firewall rules, detect packet corruption, and more.
5. Better Zenmap GUI and results viewer
While Nmap started out as a command-line tool and many (possibly most) users still use it that way, Nmap's developers have also developed an enhanced GUI and results viewer named Zenmap. One addition since Nmap 5 is a “filter hosts” feature which allows you to see only the hosts which match your criteria (e.g. Linux boxes, hosts running Apache, etc.) They have also localized the GUI to support five languages besides English. A new script selection interface helps you find and execute Nmap NSE scripts. It even tells you what arguments each script supports.
6. Faster scans
Since Nmap 5, the developers have rewritten the traceroute system for higher performance and increased the allowed parallelism of the Nmap Scripting Engine and version detection subsystems. They also performed an intense memory audit which reduced peak consumption during our benchmark scan by 90%. They made many improvements to Zenmap data structures and algorithms as well so that it can now handle large enterprise scans with ease.