The Three-Way Handshake, Ports, and Protocols
Learn about the three-way handshake, ports, and protocols and how they're used with Nmap.
What is a three-way handshake?
Before we start working with Nmap, it’s important that we understand how the three-way handshake works. Most of the scans we’ll be doing with Nmap will involve the requests and responses in a three-way handshake.
The three-way handshake is the protocol by which two computers establish a secure communication channel. There are three steps involved, which is why it’s called three-way handshake.
Establishing connection
Let’s assume there are two computers, a server and a client. Now, this is how a three-way handshake establishes a connection between two computers:
Get hands-on with 1200+ tech skills courses.