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I want to extract an IP address from a string (actually a one-line HTML) using Python.

>>> s = "<html><head><title>Current IP Check</title></head><body>Current IP Address: 165.91.15.131</body></html>"

-- '165.91.15.131' is what I want!

I tried using regular expressions, but so far I can only get to the first number.

>>> import re
>>> ip = re.findall( r'([0-9]+)(?:\.[0-9]+){3}', s )
>>> ip
['165']

But I don't have a firm grasp on reg-expression; the above code was found and modified from elsewhere on the web.

TylerH
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GoJian
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  • possible duplicate of [Regular expression to match hostname or IP Address?](http://stackoverflow.com/questions/106179/regular-expression-to-match-hostname-or-ip-address) – Denis Otkidach May 23 '10 at 16:24

6 Answers6

74

Remove your capturing group:

ip = re.findall( r'[0-9]+(?:\.[0-9]+){3}', s )

Result:

['165.91.15.131']

Notes:

  • If you are parsing HTML it might be a good idea to look at BeautifulSoup.
  • Your regular expression matches some invalid IP addresses such as 0.00.999.9999. This isn't necessarily a problem, but you should be aware of it and possibly handle this situation. You could change the + to {1,3} for a partial fix without making the regular expression overly complex.
Mark Byers
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    You can use the regex expression to accept only valid IP addresses "\\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\b" – rcbevans May 03 '13 at 14:44
  • Very nice. For those of you who were interested in the impact of (?:...), you can find it at the docs http://docs.python.org/2/library/re.html : "(?:...) A non-capturing version of regular parentheses. Matches whatever regular expression is inside the parentheses, but the substring matched by the group cannot be retrieved after performing a match or referenced later in the pattern." – RussellStewart Feb 22 '14 at 02:35
  • @o0rebelious0o Impressive regexp. For easines and in case that you're already using this python solution, you could use `ipaddress.ip_address(ip)` to check for it. – m3nda Dec 20 '19 at 00:40
6

You can use the following regex to capture only valid IP addresses

re.findall(r'\b25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?\.25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?\.25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?\.25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?\b',s)

returns

['165', '91', '15', '131']
Snehal
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    Technically, this doesn't match valid IP adresses but valid octets. There can be any number of them, which might need to be checked in a separate step. – Jakob Borg May 23 '10 at 08:27
4
import re

ipPattern = re.compile('\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}')

findIP = re.findall(ipPattern,s)

findIP contains ['165.91.15.131']
jdotjdot
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Rambo7
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4

You can use following regex to extract valid IP without following errors
1.Some detected 123.456.789.111 as valid IP
2.Some don't detect 127.0.00.1 as valid IP
3.Some don't detect IP that start with zero like 08.8.8.8

So here I post a regex that works on all above conditions.

Note : I have extracted more than 2 millions IP without any problem with following regex.

(?:(?:1\d\d|2[0-5][0-5]|2[0-4]\d|0?[1-9]\d|0?0?\d)\.){3}(?:1\d\d|2[0-5][0-5]|2[0-4]\d|0?[1-9]\d|0?0?\d)
Mohsen Sarkar
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2

easiest way to find the ip address from the log..

 s = "<html><head><title>Current IP Check</title></head><body>Current IP Address: 165.91.15.131</body></html>"
 info = re.findall(r'[\d.-]+', s)

In [42]: info

Out[42]: ['165.91.15.131']

Artem Kulikov
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user2987237
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    Could you please explain this [\d.-]+ , '- after . what it will represent – rakesh patanga Jan 11 '18 at 16:27
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    `[\d.-]+` will grab any number even if the string doesn't contains IPs, i.e: it will grab the IP and the numbers `1` & `2` in a sentence like `104.108.71.62: has versionsr: 1 vs. 2` – Ricky Levi Jun 18 '18 at 10:21
1

This is how I've done it. I think it's so clean

import re
import urllib2

def getIP():
    ip_checker_url = "http://checkip.dyndns.org/"
    address_regexp = re.compile ('\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}')
    response = urllib2.urlopen(ip_checker_url).read()
    result = address_regexp.search(response)

    if result:
            return result.group()
    else:
            return None

get_IP() returns ip into a string or None

You can substitute address_regexp for other regular expressions if you prefer a more accurate parsing or maybe change the web service provider.

Gonzalo Cao
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