Using Nmap to find open ports

Network Mapper (Nmap) is a security scanner written by Gordon Lyon. It is used to find hosts and services in a network. It first came out in September 1997. Nmap has various features as well as scripts to perform various tests such as finding the OS, service version, brute force default logins, and so on.

Some of the most common types of scan are:

• TCP connect() scan
• SYN stealth scan
• UDP scan
• Ping scan
• Idle scan