How to validate IP address in Python? [duplicate]

Question

This question already has an answer here:

• check if a string matches an IP address pattern in python? 18 answers

What's the best way to validate that an IP entered by the user is valid? It comes in as a string.

Answer 1

def is_valid_ip(ip):
    """Validates IP addresses.
    """
    return is_valid_ipv4(ip) or is_valid_ipv6(ip)

IPv4:

def is_valid_ipv4(ip):
    """Validates IPv4 addresses.
    """
    pattern = re.compile(r"""
        ^
        (?:
          # Dotted variants:
          (?:
            # Decimal 1-255 (no leading 0's)
            [3-9]\d?|2(?:5[0-5]|[0-4]?\d)?|1\d{0,2}
          |
            0x0*[0-9a-f]{1,2}  # Hexadecimal 0x0 - 0xFF (possible leading 0's)
          |
            0+[1-3]?[0-7]{0,2} # Octal 0 - 0377 (possible leading 0's)
          )
          (?:                  # Repeat 0-3 times, separated by a dot
            \.
            (?:
              [3-9]\d?|2(?:5[0-5]|[0-4]?\d)?|1\d{0,2}
            |
              0x0*[0-9a-f]{1,2}
            |
              0+[1-3]?[0-7]{0,2}
            )
          ){0,3}
        |
          0x0*[0-9a-f]{1,8}    # Hexadecimal notation, 0x0 - 0xffffffff
        |
          0+[0-3]?[0-7]{0,10}  # Octal notation, 0 - 037777777777
        |
          # Decimal notation, 1-4294967295:
          429496729[0-5]|42949672[0-8]\d|4294967[01]\d\d|429496[0-6]\d{3}|
          42949[0-5]\d{4}|4294[0-8]\d{5}|429[0-3]\d{6}|42[0-8]\d{7}|
          4[01]\d{8}|[1-3]\d{0,9}|[4-9]\d{0,8}
        )
        $
    """, re.VERBOSE | re.IGNORECASE)
    return pattern.match(ip) is not None

IPv6:

def is_valid_ipv6(ip):
    """Validates IPv6 addresses.
    """
    pattern = re.compile(r"""
        ^
        \s*                         # Leading whitespace
        (?!.*::.*::)                # Only a single whildcard allowed
        (?:(?!:)|:(?=:))            # Colon iff it would be part of a wildcard
        (?:                         # Repeat 6 times:
            [0-9a-f]{0,4}           #   A group of at most four hexadecimal digits
            (?:(?<=::)|(?<!::):)    #   Colon unless preceeded by wildcard
        ){6}                        #
        (?:                         # Either
            [0-9a-f]{0,4}           #   Another group
            (?:(?<=::)|(?<!::):)    #   Colon unless preceeded by wildcard
            [0-9a-f]{0,4}           #   Last group
            (?: (?<=::)             #   Colon iff preceeded by exacly one colon
             |  (?<!:)              #
             |  (?<=:) (?<!::) :    #
             )                      # OR
         |                          #   A v4 address with NO leading zeros 
            (?:25[0-4]|2[0-4]\d|1\d\d|[1-9]?\d)
            (?: \.
                (?:25[0-4]|2[0-4]\d|1\d\d|[1-9]?\d)
            ){3}
        )
        \s*                         # Trailing whitespace
        $
    """, re.VERBOSE | re.IGNORECASE | re.DOTALL)
    return pattern.match(ip) is not None

The IPv6 version uses "(?:(?<=::)|(?<!::):)", which could be replaced with "(?(?<!::):)" on regex engines that support conditionals with look-arounds. (i.e. PCRE, .NET)

Edit:

• Dropped the native variant.
• Expanded the regex to comply with the RFC.
• Added another regex for IPv6 addresses.

Edit2:

I found some links discussing how to parse IPv6 addresses with regex:

• A Regular Expression for IPv6 Addresses - InterMapper Forums
• Working IPv6 regular expression - Patrick’s playground blog
• test-ipv6-regex.pl - Perl script with tons of test-cases. It seems my regex fails on a few of those tests.

Edit3:

Finally managed to write a pattern that passes all tests, and that I am also happy with.

Answer 2

I only needed to parse IP v4 addresses. My solution based on Chills strategy follows:

def getIP():

    valid = False

    while not valid :

        octets = raw_input( "Remote Machine IP Address:" ).strip().split(".")

        try: valid=len( filter( lambda(item):0<=int(item)<256, octets) ) == 4

        except: valid = False

    return ".".join( octets )

Answer 3

I hope it's simple and pythonic enough:

def is_valid_ip(ip):
    m = re.match(r"^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$", ip)
    return bool(m) and all(map(lambda n: 0 <= int(n) <= 255, m.groups()))

Answer 4

I came up with this noob simple version

def ip_checkv4(ip):
        parts=ip.split(".")
        if len(parts)<4 or len(parts)>4:
            return "invalid IP length should be 4 not greater or less than 4"
        else:
            while len(parts)== 4:
                a=int(parts[0])
                b=int(parts[1])
                c=int(parts[2])
                d=int(parts[3])
                if a<= 0 or a == 127 :
                    return "invalid IP address"
                elif d == 0:
                    return "host id  should not be 0 or less than zero " 
                elif a>=255:
                    return "should not be 255 or greater than 255 or less than 0 A"
                elif b>=255 or b<0: 
                    return "should not be 255 or greater than 255 or less than 0 B"
                elif c>=255 or c<0:
                    return "should not be 255 or greater than 255 or less than 0 C"
                elif d>=255 or c<0:
                    return "should not be 255 or greater than 255 or less than 0 D"
                else:
                    return "Valid IP address ", ip

    p=raw_input("Enter IP address")
    print ip_checkv4(p)

Answer 5

From Python 3.4 on, the best way to check if an IPv6 or IPv4 address is correct, is to use the Python Standard Library module ipaddress - IPv4/IPv6 manipulation library s.a. https://docs.python.org/3/library/ipaddress.html for complete documentation.

Example :

#!/usr/bin/env python

import ipaddress
import sys

try:
    ip = ipaddress.ip_address(sys.argv[1])
    print('%s is a correct IP%s address.' % (ip, ip.version))
except ValueError:
    print('address/netmask is invalid: %s' % sys.argv[1])
except:
    print('Usage : %s  ip' % sys.argv[0])

For other versions: Github, phihag / Philipp Hagemeister,"Python 3.3's ipaddress for older Python versions", https://github.com/phihag/ipaddress

The backport from phihag is available e.g. in Anaconda Python 2.7 & is included in Installer. s.a. https://docs.continuum.io/anaconda/pkg-docs

To install with pip:

pip install ipaddress

s.a.: ipaddress 1.0.17, "IPv4/IPv6 manipulation library", "Port of the 3.3+ ipaddress module", https://pypi.python.org/pypi/ipaddress/1.0.17

Answer 6

Consider IPv4 address as "ip".

if re.match(r'^((\d{1,2}|1\d{2}|2[0-4]\d|25[0-5])\.){3}(\d{1,2}|1\d{2}|2[0-4]\d|25[0-5])$', ip):  
    print "Valid IP"  
else:
    print "Invalid IP"