How to parse valid IP's from a log file (Stackoverflow answer)

parseOutValidIPs.py

"""
http://stackoverflow.com/questions/26564513/python-valid-ips-from-each-line-on-a-text-file/26564920#26564920

iplog.txt:
	Host : 75.75.75.75 , DNS : resolved dns , Location : USA
	Host : 266.266.266.266 , DNS : resolved dns , Location : USA
	Host : 10.0.1.1 , DNS : resolved dns , Location : USA

ipclear.txt:
	75.75.75.75
	10.0.1.1
"""

import re
import socket

ipPattern = re.compile('Host : (.*) , DNS : .*')

outfile = open('ipclear.txt', 'w')

for line in open('iplog.txt').readlines():
    ipString = ipPattern.match(line).group(1)
    try:
        socket.inet_aton(ipString)
        outfile.write(ipString + '\n')
    except:
        pass

outfile.close()