How to Validate IPv4 address in Python using Regular Expression.

[abeesh ks]

if(re.match("(^[2][0-5][0-5]|^[1]{0,1}[0-9]{1,2})\.([0-2][0-5][0-5]|[1]{0,1}[0-9]{1,2})\.([0-2][0-5][0-5]|[1]{0,1}[0-9]{1,2})\.([0-2][0-5][0-5]|[1]{0,1}[0-9]{1,2})$",ip_addr)   != None):
        print "Verified as passed"
else:
        print "Verified as failed"

[SurekhaP]

Hi..
Any idea how we can accept ip address in ipv4 format as input from user in python?
with input() function it does not accept more than one decimal input!!

thanks

[bvdet]

Use raw_input() instead of input() to receive input from the user. I have taken abeesh ks's re pattern and added comments:

import re
 
ip_addr = "This is an example of an IPv4 address: 192.11.2.250"
 
patt = re.compile('''
            ^                                       # Match start of string
            ([2][0-5][0-5]|^[1]{0,1}[0-9]{1,2})     # Match decimal octet
            \.                                      # Match '.' character
            ([0-2][0-5][0-5]|[1]{0,1}[0-9]{1,2})    # Match decimal octet
            \.                                      # Match '.' character
            ([0-2][0-5][0-5]|[1]{0,1}[0-9]{1,2})    # Match decimal octet
            \.                                      # Match '.' character
            ([0-2][0-5][0-5]|[1]{0,1}[0-9]{1,2})    # Match decimal octet
            $                                       # Match end of string
            ''', re.VERBOSE)
 
m = re.search(patt, ip_addr.split()[-1])
 
if m:
    print "Valid IPv4 address"
else:
    print "Invalid IPv4 address"
 
print m.groups()

I have not verified that the re pattern is 100% valid, but it appears to work.

[SurekhaP]

thanks abeesh/bvdet. I ll try out the code :)