Well-Known Network Ports

All things you need to know about network ports for CompTIA A+ exam

File Transfer Protocol (FTP)—Data Connection

20; Make files available for download across a network (data connection port)

File Transfer Protocol (FTP)—Control connection

21; Make files available for download across a network (control connection port)

Secure Shell (SSH)

22; Make a secure connection to the command-line interface of a server.

Telnet

23; Make an unsecure connection to the command-line interface of a server.

Simple Mail Transfer Protocol (SMTP)

25; Transfer email messages across a network.

Domain Name System (DNS)

53; Facilitate identification of hosts by name alongside IP addressing.

Dynamic Host Configuration Protocol (DHCP) Server

67; Provision an IP address configuration to clients.

DHCP Client

68; Request a dynamic IP address configuration from a server.

HyperText Transfer Protocol (HTTP)

80; Provision unsecure websites and web services.

Post Office Protocol (POP)

110; Retrieve email messages from a server mailbox.

NetBIOS over TCP/IP

137/139; Support networking features of legacy Windows versions.

Internet Mail Access Protocol (IMAP)

143; Read and manage mail messages on a server mailbox.

Simple Network Management Protocol (SNMP)

161; Query status information from network devices.

SNMP trap operation

162; Report status information to a management server.

Lightweight Directory Access Protocol (LDAP)

389; Query information about network users and resources.

HTTP Secure (HTTPS)

443; Provision secure websites and services.

Server Message Block (SMB)

445; Implement Windows-compatible file and printer sharing services on a local network (also sometimes referred to as Common Internet File System [CIFS])

Remote Desktop Protocol (RDP)

3389; Make a secure connection to the graphical desktop of a computer.