I'm trying to understand something with X11 and one fact that I discovered is that the X display stuff seems to be sent through a port called "localhost:11"

So I tried the netstat -n | grep ':11'

but no results were matched.

What am I missing?

Isn't this supposed to be something called internal port redirecting(or something similar...)?

Hope someone could enlighten me...


The localhost:11 is not a port is a display number (like a session number) regarding X11. So you can't see it with netstat command.

The X connections are like this:


Somme additional information here : http://www.hungry.com/~jamie/xexport.html

  • localhost:11 is a display over TCP. So it can be seen with netstat but the port is 6011, not 11. – Stéphane Chazelas Jun 23 '14 at 9:03

As Boogy's answer says, that address scheme is more likely to be a display address. Port 11 is traditionally attributed to systat, an early mechanism to monitor the system running processes.

Recall that if you do a netstat, you would get the port name directly. To get port numbers, you need to add the -n option to netstat:

-n Show network addresses and ports as numbers. Normally netstat attempts to resolve addresses and ports, and display them symbolically.

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