127 network ports
Which service uses which number, what range it falls in and whether it needs root. This is where you come to look up 22 or 3306.
Three ranges
Well-known63
0–1023. On Unix only root may open one.
Registered63
1024–49151. Meant to be applied for, though some numbers here are custom by habit.
Dynamic1
49152–65535. The operating system picks from here for each outgoing connection, so nobody owns them.
Web11
Where a browser knocks.
Mail8
Sending mail out and fetching it back.
Files12
Moving files about, or sharing a disk.
Remote access7
Running commands or watching a screen on someone else’s machine.
Databases14
Where a database waits for queries.
Name lookup7
Turning names into addresses, or looking people and machines up.
Authentication8
Checking who you are and handing out keys.
Messaging13
Passing messages along, or queueing them up.
Monitoring5
Collecting logs and watching health.
Networking14
Running the network itself — handing out addresses, announcing routes, digging tunnels.
Dev and ops14
Ports that development and operations tools open.
Others14
Time, printing, play — the ones that fit nowhere else.
How to read this
- A port number is 16 bits, so it runs 0 to 65535. There is no port 65536.
- Opening anything at or below 1023 needs root on Unix.
- Plain and encrypted often live on different numbers — 80 and 443, for one.
- Numbers like 3000 and 8080 were never registered; those are marked as custom.
Frequently asked questions
Q. Why do port numbers stop at 65535?
They are written as a 16-bit integer. Two to the sixteenth is 65536, and counting from zero the last one is 65535.
Q. What is special about ports below 1024?
On Unix-like systems only root may open them, so that any program cannot pretend to be the web server on port 80.
Q. What is the difference between 80 and 443?
Both are the web; 443 is the one wrapped in TLS. Several such plain and encrypted pairs exist — 21 and 990, 143 and 993.
Q. Is port 3000 registered?
No. It settled in by habit among development servers. Such numbers are marked as custom in the list.
Q. Can TCP and UDP use the same number?
Yes. They have separate number spaces, so TCP 53 and UDP 53 are different places. DNS uses both.