Regex Tester for IP Addresses

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IP validation requires careful regex to reject 999.999.999.999.

Example

Pattern: ^(?:(?:25[0-5]|2[0-4]\\d|[01]?\\d\\d?)\\.){3}(?:25[0-5]|2[0-4]\\d|[01]?\\d\\d?)$\n\nTest: 192.168.1.1, 256.1.1.1

Tips

  1. 1Simple \\d{1,3} matches invalid 999.
  2. 2Each octet: 0-255.
  3. 3IPv6 is much more complex.

Frequently Asked Questions

Validate 0-255?

Yes: (25[0-5]|2[0-4]\\d|[01]?\\d\\d?)

CIDR?

Append \\/(3[0-2]|[12]?\\d)

Production?

Use IP parsing library.