Ports and Protocols

• When data is transmitted over a network, it is essentially done over what is called a port.

• You can think of ports as separate communication channels that hold specific purpose.

• For example, if you are browsing the web, you typically send traffic over port 80 or 443 because those are meant for web browsing.

• In total there are 65535 ports, but we only need to know a handful.

Top Ports & Protocols to Know :

• Among all 65535 ports, there are some ports that are known as Common Ports.

• They are used frequently for specific reasons and will be very helpful for you to understand as a hacker.

• You should attempt to commit the following ports/protocols to memory or at least have them listed somewhere that you can reference very quickly.

Top Ports & Protocols to Know Cont. :

1. Port 20/21 — File Transfer Protocol

2. Port 22 — Secure Shell

3. Port 23 — Telnet

4. Port 25 — Simple Mail Transfer Protocol

5. Port 53 — Domain Name Server

6. Port 80 — HyperText Transfer Protocol

7. Port 110 — Post Office Protocol 3

8. Port 123 — Network Time Protocol

9. Port 139 — Server Message Block Over NETBIOS

10. Port 161 — Simple Network

11. Port 389 — Lightweight Directory Access Protocol

12. Port 443 — HyperText Transfer Protocol Secure

13. Port 445 — Server Message Block

14. Port 3389 — Remote Desktop Protocol

TCP and UDP :

• When using ports, it is important to know that each port exists on both TCP & UDP.

• TCP is a connection–oriented protocol built around confirming packet delivery.

• This means that every packet that is sent over TCP has its delivery confirmed and is resent if delivery fails, making it a little slower than UDP.

• UDP is known as a connection–less protocol, meaning that it does not check for failed transmission of packets.

• As a result, UDP is faster but may result in some lost packets.