Common port numbers and what they are for

The port numbers you are most likely to meet, with the service that normally uses each. Type a number or a name to filter.

What a port is

An IP address gets data to the right device. A port number gets it to the right program on that device. A computer can run a web server, a mail server and a game at once on one address, and the port, a number from 0 to 65,535, says which of them a piece of data is for. An address and port together are written with a colon: 192.168.1.10:8080.

Programs that wait for connections "listen" on an agreed port so that others know where to find them: web servers on 80 and 443, mail on 25, and so on. Your own browser uses a random high port for its side of each conversation.

The numbers fall into three bands. 0 to 1023 are the well-known ports, registered for the classic services. 1024 to 49151 are registered for particular products. 49152 to 65535 are free for temporary use. The registrations are kept by IANA, the body that also coordinates IP addresses. A program can be set to listen on a different port from its usual one, so the list below shows convention, not a guarantee.

TCP and UDP are the two ways of carrying data. TCP checks that everything arrives in order (web pages, mail, files). UDP sends without checking, which is quicker (calls, games, DNS questions). The same number is a different port in each.

Port	Carried by	Service	What it is for
20	TCP	FTP data	File transfer: the files themselves
21	TCP	FTP control	File transfer: commands and login
22	TCP	SSH	Secure remote login and file copy (SFTP, SCP)
23	TCP	Telnet	Old remote login with no encryption; avoid it
25	TCP	SMTP	Mail passed between mail servers
53	TCP and UDP	DNS	Turning names into addresses
67	UDP	DHCP server	Handing out addresses on a local network
68	UDP	DHCP client	A device asking for an address
69	UDP	TFTP	Very simple file transfer, used by network equipment
80	TCP	HTTP	Web pages without encryption
110	TCP	POP3	Collecting mail from a mailbox
123	UDP	NTP	Setting the clock from a time server
137	UDP	NetBIOS name	Old Windows network names
139	TCP	NetBIOS session	Old Windows file sharing
143	TCP	IMAP	Reading mail that stays on the server
161	UDP	SNMP	Monitoring network equipment
389	TCP	LDAP	Directory look-ups in offices
443	TCP and UDP	HTTPS	Web pages with encryption; UDP 443 carries HTTP/3
445	TCP	SMB	Windows file and printer sharing; never open it to the internet
465	TCP	SMTPS	Sending mail with encryption from the start
500	UDP	IKE	Setting up IPsec VPN tunnels
514	UDP	Syslog	Equipment sending its logs to a collector
587	TCP	Mail submission	A mail app sending mail to its server
631	TCP	IPP	Network printing
636	TCP	LDAPS	Directory look-ups with encryption
853	TCP	DNS over TLS	Encrypted DNS look-ups
993	TCP	IMAPS	IMAP mail with encryption
995	TCP	POP3S	POP3 mail with encryption
1194	UDP	OpenVPN	A common VPN protocol
1433	TCP	Microsoft SQL Server	Database
1723	TCP	PPTP	An old, weak VPN protocol
1883	TCP	MQTT	Messages between smart devices and their hub
3306	TCP	MySQL / MariaDB	Database
3389	TCP	Remote Desktop (RDP)	Controlling a Windows computer from afar; a favourite target of attackers
3478	UDP	STUN / TURN	Helping calls and games connect through NAT
5060	TCP and UDP	SIP	Setting up internet phone calls
5222	TCP	XMPP	Chat services
5353	UDP	mDNS	Finding printers and devices on the local network by name
5432	TCP	PostgreSQL	Database
5900	TCP	VNC	Remote screen sharing
6379	TCP	Redis	In-memory data store
8080	TCP	HTTP alternate	Web servers under test, proxies, some router pages
8443	TCP	HTTPS alternate	Encrypted web admin pages
27017	TCP	MongoDB	Database
51820	UDP	WireGuard	A modern VPN protocol (its usual default port)

Open, closed and forwarded ports

A port is open when a program is listening on it and nothing in between blocks the way. It is closed when nothing is listening. A firewall can also silently drop traffic to a port, which makes it look as if nothing is there at all.

Your home router blocks connections coming in from the internet on every port unless you tell it otherwise. Port forwarding is that instruction: "send anything arriving on port 25565 to the computer at 192.168.1.20". It is needed for hosting a game server or reaching a recorder from outside, and it does not work behind carrier-grade NAT.

Ports and safety

An open port is only as safe as the program behind it. Forward a port only for something you run on purpose and keep updated.
Never expose 445 (Windows file sharing), 23 (Telnet) or 3389 (Remote Desktop) directly to the internet. Automated attacks try them on every address, all day. Use a VPN into your network for remote access.
Turn off UPnP in the router if you do not need it. It lets any program or device in the house open ports by itself.
Changing a service to an unusual port cuts down noise from automated scans but is not protection in itself.

Ports on your own computer

Addresses such as localhost:3000 or 127.0.0.1:8080 use ports too, on your own machine only. See 127.0.0.1 and localhost. To see what is listening on Windows, open Command Prompt and run:

netstat -an

Lines marked LISTENING show ports with a program waiting on them.

What port does HTTPS use?

443. Plain HTTP uses 80. Browsers add these by themselves, which is why you never type them.

Is it dangerous to have open ports?

Outgoing connections from your devices are normal and safe. The risk is in ports open to incoming connections from the internet, where an outdated or badly secured program is listening.

How many ports are there?

65,536 for TCP and the same again for UDP, numbered 0 to 65,535.