IPv4 to IPv6 Converter

IPv4 to IPv6 converter maps any valid IPv4 address to its IPv4-mapped IPv6 representation per RFC 4291 §2.5.5.2. The resulting address embeds the 32-bit IPv4 value within the 128-bit IPv6 space using the ::ffff:0:0/96 prefix — 80 zero bits, followed by 16 all-one bits (0xFFFF), followed by the IPv4 address expressed as two four-digit hexadecimal groups. For example, 8.8.8.8 converts to ::ffff:0808:0808. Dual-stack applications use this format to accept IPv4 connections through a single AF_INET6 socket without maintaining a separate IPv4 socket alongside it.

IPv4-to-IPv6 representation is not a single standard — two distinct formats exist for different purposes. This tool produces the IPv4-mapped format only. Understanding the difference is essential before applying the output to any network configuration.

RFC 4291 reserves the ::ffff:0:0/96 range — a /96 block containing 2³² addresses, one for every valid IPv4 address — within the 128-bit IPv6 address space specifically for this purpose.

The conversion follows a fixed algorithm: each of the four decimal octets is converted to a two-digit hexadecimal value. The two leftmost octets are concatenated into a four-digit hex group; the two rightmost octets form a second four-digit hex group. The ::ffff: prefix is prepended.

For 192.168.1.1: 192 → c0, 168 → a8, 1 → 01, 1 → 01 → result: ::ffff:c0a8:0101.

The conversion is reversible — strip the ::ffff: prefix, split the remaining address into one-byte hex pairs, and convert each pair back to decimal. All processing runs in the browser using JavaScript — no address data leaves the device.

Dual-stack application development. A developer building a server that binds to an AF_INET6 socket needs to represent incoming IPv4 client addresses in IPv4-mapped format. Converting the expected source addresses in advance confirms that ACL entries, logging parsers, and rate-limit keys will match the socket's representation of those clients.

Firewall and access-control list migration. A network engineer migrating from a pure-IPv4 perimeter to a dual-stack architecture needs to express existing IPv4 ACL entries in IPv4-mapped notation. Converting the source rules confirms coverage before cutover, reducing the risk of unintended allow or deny mismatches on the new stack.

Log analysis on dual-stack servers. A sysadmin reviewing nginx or Apache access logs on a dual-stack host sees entries in ::ffff:x.x.x.x notation for IPv4 clients. Converting known IPv4 addresses to their mapped equivalent allows grep and log-analysis pipelines to match entries without writing dual-format patterns.