IPv4 and IPv6 interoperability
IPv4-mapped IPv6 addresses explained
An IPv4-mapped IPv6 address lets IPv6-aware software represent an IPv4 peer in a 128-bit address format. It is a notation for compatibility, not a mechanism that upgrades IPv4 connectivity to native IPv6.
The IPv4-mapped format
The mapped prefix is ::ffff:0:0/96. The final 32 bits contain the original IPv4 address. Software can show those bits as hexadecimal IPv6 groups or with familiar IPv4 dotted-quad notation.
To calculate the hexadecimal form, group the four IPv4 octets into two pairs. For example, 185.239 becomes b9ef and 60.226 becomes 3ce2, producing ::ffff:b9ef:3ce2.
Mapped addresses are not translation addresses
IPv4-mapped
::ffff:0:0/96
Represents an IPv4 node inside IPv6-aware APIs, sockets, logs, and access-control systems. This is what the converter produces.
IPv4-compatible
::/96
An older embedded format that was used for transition mechanisms. It is deprecated and new implementations do not need to support it.
IPv4-translatable
64:ff9b::/96
Used by IPv4/IPv6 translation systems. It requires a configured translator or gateway; adding the prefix alone does not create connectivity.
IPv4-compatible and IPv4-mapped formats are defined as embedded IPv4 forms in the IPv6 addressing architecture. Algorithmic translation prefixes are a separate mechanism for translators and gateways.
Where you encounter mapped addresses
Dual-stack servers can accept IPv4 and IPv6 connections through one IPv6-aware socket. In application logs or access-control lists, an IPv4 client can then appear as an IPv4-mapped IPv6 address.
Databases, proxies, containers, load balancers, and programming-language network libraries may expose this notation. The mapped form lets software use one address representation while it handles both IP versions.
When diagnosing a log entry, convert the mapped form back to dotted-quad IPv4 before deciding whether a client belongs to a private range, loopback, CGNAT, or public space.
Do not use a mapped value as a DNS record, a native IPv6 firewall rule, or proof that the remote machine supports IPv6. Its meaning depends on the surrounding application or network stack.
IPv4 to IPv6 mapping FAQ
Does mapping give my IPv4 address native IPv6 connectivity?
No. It only changes how software represents the IPv4 value. Native IPv6 connectivity or NAT64 requires network configuration beyond this notation.
Why do I see ::ffff: in logs?
An IPv6-aware socket or framework may represent an IPv4 peer this way so it can process IPv4 and IPv6 connections with one address format.
Can I use the mapped value as a public IPv6 address?
No. It does not allocate a public IPv6 address and does not make an IPv4-only host reachable over an IPv6 route.
How can I verify a conversion?
Convert each pair of IPv4 octets to one 16-bit hexadecimal group, then place both groups after ::ffff:.
Explore special IPv4 address conversions
These curated examples explain how special IPv4 ranges retain their original routing scope when represented as IPv4-mapped IPv6 addresses.
Convert an IPv4 address
Use the converter to see compact hexadecimal, expanded, and dotted-quad mapped forms for any valid IPv4 address.
Open IPv4 to IPv6 converterTechnical references: RFC 4291 for IPv4-mapped and deprecated compatible addresses, and RFC 6052 for IPv4/IPv6 translation prefixes.