Regex to Match an Ip Address

Validating IPv4 addresses with regexp

You've already got a working answer but just in case you are curious what was wrong with your original approach, the answer is that you need parentheses around your alternation otherwise the (\.|$) is only required if the number is less than 200.

'\b((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4}\b'
    ^                                    ^

Using a RegEx to match IP addresses

You have to modify your regex in the following way

pat = re.compile("^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$")

that's because . is a wildcard that stands for "every character"

Regex for matching IPv4 addresses

The following Regex matches IPs from 0.0.0.0 to 255.255.255.255, not preceded or followed by a period or a digit:

(?<![\.\d])(?:[0-9]\.|1\d?\d?\.|2[0-5]?[0-5]?\.){3}(?:[0-9]|1\d?\d?|2[0-5]?[0-5]?)(?![\.\d])

Demo: https://regex101.com/r/UUCywc/3

Edit: to avoid matching IPs with a negative number as the first digit (eg. -127.2.1.2), and to allow IPs like 001.001.001.001, then use:

(?<![-\.\d])(?:0{0,2}?[0-9]\.|1\d?\d?\.|2[0-5]?[0-5]?\.){3}(?:0{0,2}?[0-9]|1\d?\d?|2[0-5]?[0-5]?)(?![\.\d])

Demo: https://regex101.com/r/UUCywc/6

Full Python implementation:

import re

str1 = 'Hello my name is Ben and my IP address is 127.1.1.1'
str2 = 'Hello my name is Folks and my IP address is 1.2.3.4.5'
str3 = 'Hello all, ip addresses: 1.2.3.4.5, 127.1.2.1, 127.2.1.2'

def find_ip(test_str):
    regex = re.compile(r"(?<![-\.\d])(?:0{0,2}?[0-9]\.|1\d?\d?\.|2[0-5]?[0-5]?\.){3}(?:0{0,2}?[0-9]|1\d?\d?|2[0-5]?[0-5]?)(?![\.\d])")
    return regex.findall(test_str)

print(find_ip(str1)) #['127.1.1.1']
print(find_ip(str2)) #[]
print(find_ip(str3)) #['127.1.2.1', '127.2.1.2']

How to match an ip address in mysql?

You're going to need to use REGEXP to match the IP address dotted quad pattern.

SELECT *
FROM yourtable
WHERE 
  thecolumn REGEXP '^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}$'

Technically, this will match values that are not valid IP addresses, like 999.999.999.999, but that may not be important. What is important, is fixing your data such that IP addresses are stored in their own column separate from whatever other data you have in here. It is almost always a bad idea to mix data types in one column.

mysql> SELECT '9876543210' REGEXP '^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}$';
+---------------------------------------------------------------------------+
| '9876543210' REGEXP '^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}$' |
+---------------------------------------------------------------------------+
|                                                                         0 |
+---------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT '987.654.321.0' REGEXP '^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}$';
+------------------------------------------------------------------------------+
| '987.654.321.0' REGEXP '^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}$' |
+------------------------------------------------------------------------------+
|                                                                            1 |
+------------------------------------------------------------------------------+

Another method is to attempt to convert the IP address to a long integer via MySQL's INET_ATON() function. An invalid address will return NULL.

This method is likely to be more efficient than the regular expression.

You may embed it in a WHERE condition like: WHERE INET_ATON(thecolumn) IS NOT NULL

SELECT INET_ATON('127.0.0.1');
+------------------------+
| INET_ATON('127.0.0.1') |
+------------------------+
|             2130706433 |
+------------------------+

SELECT INET_ATON('notes');
+--------------------+
| INET_ATON('notes') |
+--------------------+
|               NULL |
+--------------------+

SELECT INET_ATON('56.99.9999.44');
+----------------------------+
| INET_ATON('56.99.9999.44') |
+----------------------------+
|                       NULL |
+----------------------------+

Regex for find All ip address except IP address starts with 172

. in a regex is character that matches everything. To use it in this context, you must escape it.

Also to limit it to just ip addresses that start with 172, simply hardcode it into your regex like so:

^172\.\d{1,3}\.\d{1,3}.\d{1,3}$

Debuggex Demo

You could then use this to filter out any matches already made.

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Alternatively, if you're not starting with a list of ip addresses, you could use a negative look-ahead to grab them all straight away.

^(?!172)\d{1,3}\.\d{1,3}\.\d{1,3}.\d{1,3}$

Debuggex Demo

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Be a little careful in that this may match more than ip addresses - for example 400.660.226.602 would be captured - even though real IP4 addresses do not contain numbers higher than 255. Perhaps this won't affect your use case - but it's something to remember.

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As per the comments below, if you are searching for IP addresses anywhere in the document, rather than on their own line, use \b instead of ^ and $

\b(?!172)\d{1,3}\.\d{1,3}\.\d{1,3}.\d{1,3}\b

Debuggex Demo

This would match log formats for example, which contain an ip address within the message rather than on it's own line.

[10:01:22] Connection from 10.14.242.211 established.

Regex to match an IP address

Don't use a regex when you don't need to :)

$valid = filter_var($string, FILTER_VALIDATE_IP);

Though if you really do want a regex...

$valid = preg_match('/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\z/', $string);

The regex however will only validate the format, the max for any octet is the max for an unsigned byte, or 255.

This is why IPv6 is necessary - an IPv4 address is only 32bits long and the internet is popular :)

How can I find an IP address in a long string with REGEX?

import re

secv = "90.123.1.100 akmfiawnmgisa gisamgisamgsagr[sao l321r1m r2p4 2342po4k2m4 22.33.4.aer 1.2.3.5344 99.99.99.100 asoifinagf sadgsangidsng sg 13.18.19.100 1.2.3.4"

b = re.findall(r"(?:\s|\A)(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})(?=\s|\Z)",secv)

b = list(filter(lambda x: all([int(y) <= 255 for y in x.split('.')]), b))

print(b)

To make it more interesting I added IP addresses at the beginning and end of your string. I am assuming that the ip address needs to be separated by white space on both sides if not at the beginning or end of the string. So I added to the REGEX at the beginning a non-capturing group (?:\s|\A) that will match either a white space character or the beginning of the string. I have also added to the end of the REGEX a lookahead assertion (?=\s|\Z) that will match a single white space character or the end of the line without consuming any characters. The above prints out:

['90.123.1.100', '99.99.99.100', '13.18.19.100', '1.2.3.4']

javascript regular expression to check for IP addresses

The regex you've got already has several problems:

Firstly, it contains dots. In regex, a dot means "match any character", where you need to match just an actual dot. For this, you need to escape it, so put a back-slash in front of the dots.

Secondly, but you're matching any three digits in each section. This means you'll match any number between 0 and 999, which obviously contains a lot of invalid IP address numbers.

This can be solved by making the number matching more complex; there are other answers on this site which explain how to do that, but frankly it's not worth the effort -- in my opinion, you'd be much better off splitting the string by the dots, and then just validating the four blocks as numeric integer ranges -- ie:

if(block >= 0 && block <= 255) {....}

Hope that helps.

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