Regular Expression - IPv4 (Perl / Java)

regex-ipv4.md

Match: 0.0.0.0-255.255.255.255

Perl / PCRE

$input =~ /^(?:(25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)\.){3}(?1)$/;

grep -P '^(?:(25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)\.){3}(?1)$' <<<"$input"

Java

Pattern.compile("^(?:(?:25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]\\d|\\d)\\.){3}(?:25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]\\d|\\d)$")
       .matcher(input).matches();

References:

• https://extendsclass.com/regex-tester.html
• https://regex101.com
• https://regexr.com
• https://perldoc.perl.org/perlre
• https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html