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How to Get All IP Addresses From a File Using RegEx and PowerShell

How to Get All IP Addresses From a File Using RegEx and PowerShell

 By Charles Joseph | Cybersecurity Researcher
 Published on December 26th, 2023
This post was updated on February 29th, 2024

I’m a Linux guy, so PowerShell isn’t exactly my forte, but when I found myself on a Windows 10 box without my familiar tools, I had to improvise.

I attempted to get a list of unique IP addresses from a text file. If I were on a *nix box, I’d issue the following command.

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$ grep -iEo “[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}” <filename> | sort | uniq -c

Unfortunately, Windows doesn’t natively have the grep command, so I did some digging.

I discovered that Windows maintains a program called findstr, which has a similar function albeit severely limited. You can’t narrow the output to matched text only.

So if you’re searching for IP addresses, and a line of text contains one with some additional surrounding text, findstr will return the entire line. This isn’t helpful.

So, I fired up PowerShell and issued the following command to get a similar output.

PS C:\Users\User\Desktop> $ips = Get-Content file.txt | Select-String -Pattern “[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}” -AllMatches | ForEach-Object {
$_.Matches | ForEach-Object {
} | Group-Object -NoElement

PS C:\Users\User\Desktop> $ips

Count Name
—– —-

Special thanks to Adam MacMurray for debugging a prior PS command that only pulled the first IP address from a line.

"Amateurs hack systems, professionals hack people."
-- Bruce Schneier, a renown computer security professional
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