ZenMap (NMap) is a deep network or host scanner for determining the state of scanned objects (ports and corresponding services).
The following methods are used for scanning: UDP, TCP (connect), TCP SYN (half-open), FTP-proxy (breakthrough via ftp), Reverse-ident, ICMP (ping), FIN, ACK, Xmas tree, SYN and NULL scanning, etc.
Additional features: OS detection, "invisible" scanning, dynamic delay calculation and packet retransmission, parallel scanning, detection of inactive hosts, scanning using false hosts, detection of the presence of packet filters, direct RPC scanning, scanning using IP fragmentation, etc.