Networkingflags: g

IP Address with CIDR Notation

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

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Available in

JSSupported

JavaScript / ECMAScript

Browser-native RegExp. Default if you don't pick.

PYSupported

Python (re)

CPython stdlib `re`. Unicode-aware `\w` and `\d` by default.

GOSupported

Go (RE2)

Linear-time matching. No backreferences or lookarounds.

Pattern

regexengine-agnostic
(?:(?: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)

Raw source: (?:(?: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)

How it 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

—

Common use cases

  • •Firewall and security-group rule validation
  • •Network configuration file parsing
  • •VPC/subnet CIDR input validation
  • •IP allowlist/blocklist enforcement

Related patterns

Private IP Address (RFC 1918)

Networking

Match IPv4 addresses in the RFC 1918 private ranges: 10/8, 192.168/16, and 172.16/12.

IPv4 Address

Networking

Match valid IPv4 addresses with each octet constrained to 0–255.

IPv6 Address

Networking

Match full (non-compressed) IPv6 addresses written as eight colon-separated hextets.

MAC Address

Networking

Match 48-bit MAC addresses written with colon or hyphen separators (e.g. 00:1A:2B:3C:4D:5E).

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