UUUP Tools

Encoding & Decoding

IPv4-Mapped IPv6 Address Converter

Convert an IPv4 address to IPv4-mapped IPv6 forms, including compressed, hex-compressed, and fully expanded notations. Useful for dual-stack log comparison and allowlist drafting. Conversion runs locally in the browser.

Quick switch→Subnet Calculator
IPv4IPv6Networking
Quick switch:Subnet CalculatorURL Parser

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Copy this tool URL or open the system share sheet on a supported device.

Use cases

  • Rewrite IPv4 access-log clients as mapped IPv6
  • Compare compressed and expanded IPv6 representations
  • Draft candidate addresses for dual-stack allowlists

How to use

  1. Enter a dotted-decimal IPv4 address (CIDR or log snippets also work when an IPv4 is present)
  2. Review mapped, hex-compressed, and expanded outputs
  3. Copy the format you need

Example input and output

IPv4

192.168.0.1

IPv4-mapped

::ffff:192.168.0.1

FAQ

Can it convert arbitrary IPv6 back to IPv4?

No. This tool focuses on IPv4 → IPv4-mapped IPv6. It does not reverse-parse arbitrary IPv6 addresses.

What does ::ffff:192.168.0.1 mean?

It is the standard way to embed an IPv4 address in IPv6 space, often used when dual-stack services represent IPv4 clients on IPv6 sockets.

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