301‐reading 2 - Skalyx866/Notes GitHub Wiki

What is a port? Describe it with an analogy that would help a family member understand.

A port is a software port that is open on a computer to allow designated services to connect to the computer. Think of a computer like a switchboard and ports as the sockets where you are redirecting the calls.

What does a port scanner send to a port to check the current status?

The port scanner sends a SYN packet to a port to check the current status.

When a port scanner sends a request to connect, what are the three possible responses? Describe them.

Either the port does not respond where the packet was blocked, the port is closed where it does not take the packet, or if it is open where it sends a SYN-ACK back.

What is the difference between TCP and UDP?

UDP is a connectionless protocol but does not have the error handling of TCP.

Telnet: Port 23 an unencrypted messaging protocol that sends messages in plain text SSH: Secure shell on port 22, a lot like telnet but is encrypted DNS: Domain name server on port UDP port 53, is a server holding domain names of a company. SMTP: Simple mail transfer protocol: port 25, uses to send out emails.

Source: What is a Port Scanner and How Does it Work?, Common Ports