Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

On my Mac, I have a UDP port that is "already in use", but doesn't have an associated process:

sudo netstat -na | grep "udp.*\.500\>"

shows

udp4       0      0  192.168.50.181.500     *.*                               
udp4       0      0  192.168.29.166.500     *.*                               

sudo lsof doesn't show a process on port 500 (ie sudo lsof -i:500 -P reports nothing).

Note I'm using 'sudo' on both commands so it should show all processes. (rebooting works, but looking for something less disruptive)

How can I unbind port 500 so I can use it again?

share|improve this question

1 Answer 1

Are you using sudo to run lsof as root? If not, it'll only be able to see files opened by processes you own, and this is probably a system process.

Port 500 is normally used for the isakmp, which is part of the IPSec suite. It'll generally show up on a Mac as a side effect of an IPSec-based VPN service.

share|improve this answer
    
Yes, I'm using sudo on both commands. Yes, the actual problem is my vpn client won't start (fails with an "address already in use" error). –  Chocohound Nov 12 '12 at 14:57

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.