Perl one liner + regular expression to match part of word

Question

I write Perl one liner code in order to match IP address according to the following rule:

match only the three first octets while the four octet must be valid 0-255 , additional to that number or " . " must not be exists before the first octet and number or " . " must not be exist also after the four octet

example

 export IP=100.187.34

example of IP's that should matched

:100.187.34.12:.10
IP=100.187.34.100$
AAA100.187.34.199BBB
address:100.187.34.210+

example of IP's that shouldn't matched

 55.100.187.34.99
 .100.187.34..
 100.187.34.100.1
 100.187.34.2100
 1.100.187.34
 100.187.34.1.1

so this is my code (not work according to my rules):

      echo [...]xxx.xxx.xxx.xxx[...]   |    perl  -pe 'print if  /(?<![\d.])\Q$ENV{IP}\E(?=\.(?:1?\d?\d|2[0-4][0-9]|25[0-5])(?!\d))/; '  

the problem is my code matched almost any number

please advice what I need to fix in my code in order to match the IP's only according to the rules

Answer 1

Here are some examples of IP regexp matching from O'Reilly's Regular Expressions Cookbook:

Simple regex to check for an IP address:

^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$

Accurate regex to check for an IP 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]?)$

Simple regex to extract IP addresses from longer text:

\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b

Accurate regex to extract IP addresses from longer text:

\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

Simple regex that captures the four parts of the IP address:

^([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})$

Accurate regex that captures the four parts of the IP address:

^(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]?)\.↵
(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$

Answer 2

 perl -e '$v=quotemeta($ENV{IP});print if /$v\.(?:1?\d?\d|2[0-4][0-9]|25[0-5])(?!\d)/?1:0'