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IP Address Validator

Validate and classify IPv4 and IPv6 addresses.

Use the IP Address Validator tool

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What this ip address validator does

IP Address Validator checks whether a string is a syntactically valid IPv4 or IPv6 address, then classifies it. You can see at a glance whether an address is private (RFC 1918), loopback, link-local, multicast, carrier-grade NAT, a documentation address or globally routable.

Classification is useful during incident review and access-control work. An address that “looks internal” may actually be a public range owned by a cloud provider, and a public-looking address may be reserved for documentation and therefore should never appear in real traffic.

Why use it

  • Validate user-supplied addresses before storing or querying them.
  • Classify log entries as internal, external or special-purpose.
  • Normalise IPv6 input so equivalent addresses compare consistently.

How to use it

  1. 1Paste one address per line for bulk validation.
  2. 2Press Validate to parse every line.
  3. 3Review validity, address family, normalised form and classification.
  4. 4Copy the results as a table or JSON.

Worked examples

Private address

Input

192.168.10.5

Output

Valid IPv4 · private (RFC 1918) · unicast · normalized 192.168.10.5

CGNAT address

Input

100.64.12.9

Output

Valid IPv4 · shared address space (RFC 6598) · not globally routable

Common mistakes

  • Using a regex alone to validate IPv4; it accepts leading zeros in some patterns that real parsers reject or interpret inconsistently.
  • Assuming 172.15.0.1 is private — only 172.16.0.0 to 172.31.255.255 is RFC 1918.
  • Forgetting to strip brackets from an IPv6 literal copied from a URL.

Frequently asked questions

What counts as a private IPv4 address?
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. Loopback is 127.0.0.0/8 and link-local is 169.254.0.0/16.
Is 100.64.0.0/10 private?
It is shared address space for carrier-grade NAT (RFC 6598). It is not globally routable, but it is not RFC 1918 private space either.
How are IPv6 zones handled?
A zone index such as %eth0 is link-scoped and not part of the address. The validator separates and reports it instead of rejecting the address.

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