Common ports and protocols
Here are a list of common ports and protocols you will see when scanning networks.

When you are scanning networks, there are some common ports and protocols that you will see again and again. Here is a list of common TCP and UDP ports, with short descriptions of what each one is used for.
TCP
Common TCP ports:
- Port 21 is FTP - File Transfer Protocol (FTP) is used to transfer files to and from a remote location.
- Port 22 is SSH - Secure Shell (SSH) allows you to send remote commands to a server. Traffic over SSH is encrypted.
- Port 23 is Telnet - Telnet allows you to send remote commands to the server. Traffic over telnet is not encrypted.
- Port 25 is SMTP - Simple Mail Transfer Protocol (SMTP) is an e-mail protocol.
- Port 53 is DNS - Domain Name Server (DNS) is used to resolve domain names to IP addresses.
- Port 80 is HTTP - Hypertext Transfer Protocol (HTTP) is an insecure and unencrypted protocol used for communicating between a client and a server. It is commonly used for web servers.
- Port 110 is POP3 - Post Office Protocol version 3 (POP3) is an e-mail protocol.
- Port 139 is SMB - Samba (SMB) is a file share protocol. This port is typically used on older versions of Windows.
- Port 143 is IMAP - Internet Message Access Protocol (IMAP) is an e-mail protocol.
- Port 443 is HTTPS - Hypertext Transfer Protocol Secure (HTTPS) is the secure and encrypted version of HTTP, a protocol used for communicating between a client and a server. It is commonly used for web servers.
- Port 445 is SMB - Samba (SMB) is a file share protocol. This port is typically used on newer versions of Windows.
UDP
Common UDP ports:
- Port 53 is DNS - Domain Name Server (DNS) is used to resolve domain names to IP addresses.
- Port 67 and 68 are DHCP - Dynamic Host Configuration Protocol (DHCP) is used for managing IP addresses within a network.
- Port 69 is TFTP - Trivial File Transfer Protocol (TFTP) is similar to FTP, but uses UDP instead of TCP.
- Port 161 is SNMP - Single Network Management Protocol (SNMP) provides a framework for asking devices about their performance and configuration over the network. The protocol is used by many different network management tools.