Nmap
Nmap (Network Mapper) is a network security scanner.
Features
General features:
- Host discovery
- Port scanning (enumerating open/closed/filtered ports on one or more target hosts)
- Service detection (determining service types and version numbers)
- OS detection
Other features:
- IP protocol scan
- Uptime detection (using TCP timestamps
- Traceroute
- DNS resolution
- Idle scan (using "zombies")
- FTP bounce scan (using proxy FTP connections)
- etc
Typical uses
- Identifying open ports on a compromised host
- Auditing the security of a network, by identifying unexpected computers