nmap
nmap is used scan large networks to determine which hosts are up and what services they are offering. It supports the following scanning techniques:
- UDP
- TCP connect()
- TCP SYN (half open)
- ftp proxy (bounce attack)
- Reverse-ident
- ICMP (ping sweep)
- FIN
- ACK sweep
- Xmas Tree
- SYN sweep
- IP Protocol
- Null scan
nmap also supports
- Remote OS detection via TCP/IP fingerprinting
- Stealth scanning
- Dynamic delay and retransmission calculations
- Parallel scanning
- Detection of down hosts via parallel pings
- Decoy scanning
- port filtering detection
- Direct (non-portmapper) RPC scanning
- Fragmentation scanning
- Flexible target and port specification.