If I want to find out what process is listening on what socket, I can use netstat/TCPview and will immediately see it. However, it is possible to bind to an address without listening. If this is done, it does not show up in netstat/TCPview, but does block the socket.
import socket s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind(('0.0.0.0',12345))
The port is now bound, and attempting to execute the same code in a second instance while the first is still running will result in an error. However, unless you actually start listening on that port using
the port does not show up in netstat/TCPview.
The question is: Is it possible to see what ports are bound (but not listening), and which process is binding them?
The background of this is that I
have had a moving range of 1976 ports that cannot be bound, and I want to know what causes this. In the meantime, I determined through trial and error that Internet Connection Sharing was blocking those ports, but I am still curious about the answer to this question.
Edit: Due to popular request, here is the code I used to find those ports:
import time import socket for i in range(0,65536): try: print "Listening on port", i, '...', serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) serversocket.bind(('0.0.0.0', i)) serversocket.listen(5) #time.sleep(0.1) serversocket.close() print "ok" except: print "FAIL"
(you may want to pipe the output to grep and filter for FAIL only)