I am trying to get all the processes listening for a network connection on Mac OS X. netstat does not have the -p option and I am trying with lsof

lsof -i -sTCP:LISTEN

gives me a fair list of listening processes but not all. I can for example telnet to port 10080 where I have a process listening for a connection but this is not shown in the output of lsof. What am I missing?

$ telnet localhost 10080
Trying ::1...
Connected to localhost.
Escape character is '^]'.
telnet> Connection closed.


$ sudo lsof -n -i | grep 10080
  • 3
    Does the output of lsof say amanda instead of 10080? – Jon Lin Dec 15 '11 at 13:56
  • 3
    @JonLin I didn't notice that the -n only affects addresses and not ports. To get port numbers I have to use -P too. Thanks – Matteo Dec 15 '11 at 14:35
  • 3
    @JonLin: but you have post lsof -i -sTCP:LISTEN , and it without the -n and it didn't reveal the 10080 too. So you have to use the -P. – Hanan N. Dec 15 '11 at 17:30
sudo lsof -iTCP -sTCP:LISTEN
sudo lsof -iTCP -sTCP:LISTEN -P
sudo lsof -iTCP -sTCP:LISTEN -P -n
sudo lsof -iTCP -sTCP:LISTEN -n

All return the same 32 entries (... | wc -l) on my heavily used Lion MBP.

-P -n prevents lsof from doing name resolution, and it doesn't block. Missing either one of these, it can be very slow.

For UDP: sudo lsof -iUDP -P -n | egrep -v '(127|::1)'. Without -n and -P, it takes a long time.

Reminder: This does not include firewall settings.

  • 3
    Yes the problem was the missing -P. I wrongly assumed -n applied not only to IPs but port numbers too. – Matteo Dec 29 '11 at 7:04
  1. First find out the Process Id (pid) which has occupied the required port (e.g 5434):

    ps aux | grep 5434
  2. Kill that process:

    kill -9 <pid>
  • 5
    ps aux does not list the ports a process is using – Matteo Jul 31 '15 at 12:12
  • I agree with Matteo; are you sure you didn't do something like netstat -anp | grep 5434 (which will return a list of stuff that is listening on 5434, and the first or second column is the pid?) – Foon Oct 8 '15 at 12:29
  • 6
    Thus could only work in a situation where a process was called with port number given explicitly in the execution string and that part of the string would be matched by grep. – techraf Mar 16 '16 at 1:01
  • 1
    Using kill -9 as a first option for getting rid of a process is an extreme choice. Also, this doesn't actually answer the question, which isn't about killing things, but finding out what's running. – lindes Dec 16 '17 at 4:07

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