Currently I'm working on a regular expression wrote in PCRE2 to check a range of IP address

^(10\.). |(172\.16). |(192\.168). 

I need the regular expression to check also if in the string I can find any ip between 172.16.X.X - 172.31.X.X

The current regex it's working but not checking this range specifically ... it's capturing everything that's 172.16.X.X

I tried ^(10\.). |(172\.[16-31]). |(192\.168). but It doesn't work in this way.

Also I'm using https://regex101.com/ to debug this expression ... is it a good way to check if it's right?

CodePudding user response：

You can use

\b(?:(?:192\.168|172(?:\.(?:1[6-9]|2\d|3[01])))(?:\.\d{1,3}){2}|10(?:\.\d{1,3}){3})\b

• \b A word boudnary to prevent a partial word match
• (?: Non capture group
  • (?: Non capture group
    • 192\.168 Match 192.168
    • | Or
    • 172(?:\.(?:1[6-9]|2\d|3[01])) Match 172. and then 16 till 31
  • ) Close non capture gorup
  • (?:\.\d{1,3}){2} Match 2 times . and 1-3 digits
  • | Or
  • 10(?:\.\d{1,3}){3} Match 10 and 3 times . and 1-3 digits
• ) Close non capture group
• \b A word boundary

Regex demo

If you want to make the \d{1,3} digits more specific, then you can also use:

(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)