Python (re)

IP Address with CIDR Notation in PY

Match IPv4 addresses with CIDR prefix notation such as 10.0.0.0/8 or 192.168.1.0/24.

Pattern

regexPY

(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\/(?:3[0-2]|[12]?\d)   (flags: g)

Python (re) code

pyPython

import re

pattern = re.compile(r"(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\/(?:3[0-2]|[12]?\d)")
input_text = "10.0.0.0/8"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

How the pattern works

The IPv4 portion uses alternation to strictly validate each octet in the 0–255 range (same as the standalone IPv4 pattern). \/(?:3[0-2]|[12]?\d) appends a / and a CIDR prefix constrained to 0–32.

Examples

Input

10.0.0.0/8

Matches

10.0.0.0/8

Input

192.168.1.0/24

Matches

192.168.1.0/24

Input

999.0.0.0/33

No match

—

Same pattern, other engines

JavaScript / ECMAScript

Supported

See how this pattern looks (and behaves) in JavaScript's built-in RegExp.

Go (RE2)

Supported

See how this pattern looks (and behaves) in Go's `regexp` package (RE2 engine).

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