Python Socket - getting lan connected server host names

Question

I am trying to get LAN connected server's host names, so I can run query over these servers with hostname:

import socket
IP_RANGE = 10
hostNamesList = []
socket.setdefaulttimeout(0.1)
for i in range(IP_RANGE):
    try:
        hostNamesList.append(socket.gethostbyaddr("192.168.1.%s" % i)[0])
    except:
        pass

print hostNamesList

The above code takes several minutes to scan selected IP range, even if I set the timeout to 0.1 seconds.

Is there anything that I did wrong, or any way(s) to get host names faster?

Answer 1

You are probably running into long DNS or SAMBA lookup (just a guess). It's more of a network related behaviour, not python. Try running Your script with profiler: python -m cProfile -s tottime lookup.py

If my guess is correct You'd see a long _socket.gethostbyaddr timing, then the only good option is to try paralleling Your code (or improving network settings for better lookup time).

Answer 2

i have solved my problem thanks to yan's suggestion.It takes about 10 seconds instead of several minutes

import socket
from threading import Thread


hostNamesList=[]
def searchForSingleIP(i):
    try:
        hostNamesList.append(socket.gethostbyaddr("192.168.1.%s" % str(i) )[0])

    except:
        pass

for i in range(256):
    worker = Thread(target = searchForSingleIP, args = (i,))
    worker.start()
    worker.join(timeout=0.05)

print hostNamesList