RegeX code for PowerShell Lookbehind not working matching on IP Addressing

Question

I'm trying to parse a number of log files for IP addresses using PowerShell, but within those files I also have a number of false positives which are actually version numbers. There may be more but as a first start I wanted to grab all IPs that are not preceded by Version=.

I've tried a number of different variations of my Regex with no real success and hacking around in regex101.com has also given me no fruits.

(?<!Version=)(?<Address>((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]?))

Ideally it should be something like:

Not Match Version=10.0.0.1
Match 10.0.0.1
Match IPAddress=10.0.0.1
Match IP=10.0.0.1

etc.

Please edit the question and add a few samples of data that should be matched and that shouldn't. Whilst at it, remove any powershell-version tags, as those should be used when the issue is about a specific version. — vonPryz
– vonPryz, Commented Apr 25, 2019 at 11:47

Tomalak · Accepted Answer · 2019-04-25 11:48:38Z

4

Add word boundaries (\b):

(?<!Version=)\b(?<Address> ... )\b

This prevents the match from starting within the IP address, which would otherwise happen. Without word boundaries, the area in square brackets would be a match: Version=1[0.0.0.1]

answered Apr 25, 2019 at 11:48

Tomalak

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