WTF? Who owns my port?

java.net.BindException: Address already in use: JVM_Bind :80
   at org.apache.tomcat.util.net.JIoEndpoint.init(JIoEndpoint.java:549)
...at java.net.ServerSocket.(ServerSocket.java:141)
...at org.apache.tomcat.util.net.JIoEndpoint.init(JIoEndpoint.java:538)
... 12 more

Familiar situation? Someone is using our port, to find out who is this bad guy just execute the following command in a shell:

windows	linux
C:\Windows> netstat -an *	$ sudo netstat -anp | grep PORT_NUMBER

* Make sure that you run it as administrator on Windows.    | find "PORT_NUMBER"  doesn't work because output for each item is 3 lines, sorry :(