Common Network Ports

Question 1

FTP (File Transfer Protocol)

Answer 1

Uses tcp/20 (data) and tcp/21 (control) to transfer files between systems. Requires quthentication and supports full file management.

Question 2

SSH (Secure Shell)

Answer 2

Uses tcp/22 for encrypted remote console access. A secure alternative to Telnet.

Question 3

Telnet

Answer 3

Uses tcp/23 to connect remotely to devices. Not encrypted, so it’s rarely used in modern secure environments.

Question 4

SMTP (Simple Mail Transer Protocol)

Answer 4

Uses tcp/25 to send emails between servers and from devices to mail servers.

Question 5

DNS (Domain Name System)

Answer 5

Uses udp/53 (and sometimes tcp/53) to convert domain names into IP addresses.

Question 6

DHCP (Dynamic Host Configuration Protocol)

Answer 6

Uses udp/67 and udp/68 to automatically assign IP addresses and configuration to devices.

Question 7

HTTP (Hypertext Transfer Protocol)

Answer 7

Uses tcp/80 for unencrypted web browsing.

Question 8

HTTPS (HTTP Secure)

Answer 8

Uses tcp/443 for encrypted web communication using SSL/TLS.

Question 9

POP3 (Post Office Protocol v3)

Answer 9

Uses tcp/110 to retrieve email from a server. Downloads and usually removes it from the server.

Question 10

IMAP4 (Internet Message Access Protocol v4)

Answer 10

Uses tcp/143 to retrieve email while keeping messages on the server. Supports multiple clients.

Question 11

SMB (Server Message Block)

Answer 11

Uses tcp/445 for Windows file and printer sharing. Can also operate over NetBIOS.

Question 12

NetBIOS

Answer 12

Uses udp/137 (name service) and tcp/139 (session service) for older Windows networking.

Question 13

SNMP (Simple Network Management Protocol)

Answer 13

Uses udp/161 (queries) and udp/162 (traps) to manage and monitor network devices.

Question 14

LDAP (Lightweight Directory Access Protocol)

Answer 14

Uses tcp/389 to access and maintain distributed directory information (e.g., Active Directory).

Question 15

RDP (Remote Desktop Protocol)

Answer 15

Uses tcp/3389 for remote graphical desktop access to Windows systems.