# Nmap

Nmap is a tool for network discovery.

Read the nmap book: https://nmap.org/book/

There are different types of scans, some of them send packets and some of them do not. Sending specific packets to specific ports is how you do host discovery.

# Host discovery

• ARP ping

Default on local ethernet. Low weight and not threatening.

ICMP protocol

• ICMP ping

TCP or UDP layer scans to detect if host is up.