Common TCP & UDP Ports

Well-known port numbers for network services.

Well-known ports (0-1023) identify the standard services that run on networked hosts. This table covers the ports you will actually use when configuring firewalls, ACLs, and services: SSH, DNS, HTTP and HTTPS, mail, NTP, DHCP, SNMP, and the database and remote-access ports.

Port numbers are 16 bits wide, so each transport protocol has 65,535 ports. Ports 0 to 1023 are the well-known ports assigned to standard services, 1024 to 49151 are registered ports used by vendors and applications, and 49152 to 65535 are the dynamic or ephemeral ports a client picks for its side of a connection. When you write a firewall rule or an ACL, the well-known ports are the ones you will match most often, and the table also covers common alternates such as HTTP on 8080 so a service that is not on its default port does not surprise you.

Use it as a quick lookup when writing firewall rules.

Port	Proto	Service	Description
20	TCP	FTP Data	File Transfer Protocol (data channel)
21	TCP	FTP Control	File Transfer Protocol (control)
22	TCP	SSH	Secure Shell
23	TCP	Telnet	Unencrypted remote access (avoid)
25	TCP	SMTP	Mail transfer between servers
53	UDP/TCP	DNS	Domain Name System
67/68	UDP	DHCP	Dynamic Host Configuration Protocol
80	TCP	HTTP	Hypertext Transfer Protocol
110	TCP	POP3	Post Office Protocol v3
123	UDP	NTP	Network Time Protocol
143	TCP	IMAP	Internet Message Access Protocol
161/162	UDP	SNMP	Simple Network Management Protocol
389	TCP	LDAP	Lightweight Directory Access Protocol
443	TCP	HTTPS	HTTP over TLS/SSL
514	UDP	Syslog	System logging
587	TCP	SMTP	Mail submission (authenticated)
636	TCP	LDAPS	LDAP over TLS/SSL
993	TCP	IMAPS	IMAP over TLS/SSL
995	TCP	POP3S	POP3 over TLS/SSL
1194	UDP	OpenVPN	OpenVPN default port
1812/1813	UDP	RADIUS	Authentication & accounting
3389	TCP	RDP	Remote Desktop Protocol
5432	TCP	PostgreSQL	PostgreSQL database
8080	TCP	HTTP Alt	HTTP alternative / proxy
8443	TCP	HTTPS Alt	HTTPS alternative

Frequently Asked Questions

What is port 8080 used for?

Port 8080 is a common alternate HTTP port. Application servers, proxies, and development servers use it when they cannot bind to port 80, either because another service already holds 80 or because the process cannot run with the privileges that low ports require. Seeing 8080 in a URL usually means the service is not on its default port.

How many TCP and UDP ports are there?

65,535 per protocol. Port numbers are 16 bits wide, so TCP and UDP each have the same range from 1 to 65,535, with port 0 reserved. The two protocols number their ports independently, so TCP port 53 and UDP port 53 are separate listeners.

What is the difference between TCP and UDP ports?

The number means the same thing, but the transport differs. TCP ports carry connection-oriented sessions with a handshake, ordering, and retransmission, while UDP ports carry connectionless datagrams with no delivery guarantee. Services such as DNS and DHCP listen on both.

Which ports are well known?

Ports 0 to 1023 are the well-known ports that IANA assigns to standard services, such as 22 for SSH, 25 for SMTP, 53 for DNS, 80 for HTTP, 443 for HTTPS, and 3389 for RDP. The registered range 1024 to 49151 holds vendor and application ports, and 49152 to 65535 is for ephemeral client ports.

What is port 80 used for?

Port 80 carries unencrypted HTTP web traffic. HTTPS uses port 443, and any service that serves web pages over TLS should be reached on 443 so the encryption is never downgraded.

What port does DNS use?

DNS uses UDP port 53 for most queries and TCP port 53 for zone transfers and for responses too large to fit in a single UDP packet. Blocking port 53 outbound at the firewall is a common way to force clients onto your own resolvers.

What is an ephemeral port?

An ephemeral port is the temporary source port a client picks from the dynamic range (49152 to 65535) for the duration of a connection. It lets many clients share one destination port on a server, and the port is released when the connection closes.

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