Skip to main content

IPv4-Mapped Addresses on the Wire Considered Harmful

Document Type Expired Internet-Draft (individual)
Expired & archived
Authors Christopher Y. Metz , Jun-ichiro Itoh
Last updated 2003-10-23
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


The IPv6 Addressing Architecture [Hinden, 1998] defines the 'IPv4-mapped IPv6 address.' These addresses are used in the IPv6 basic API [Gilligan, 1999] to denote IPv4 addresses using AF_INET6 sockets. These addresses are used in protocol proposals such as SIIT [Nordmark, 2000] to denote IPv6 communication using AF_INET6 sockets. Therefore, IPv4-mapped addresses have two different meanings, and they are not distinguishable from the user-land applications. This draft discusses security threats due to this ambiguity of IPv4-mapped address. It also discusses threats due to the additional complexities introduced by IPv4-mapped addresses. Finally, it proposes to resolve these problems by forbidding protocols from using IPv4-mapped addresses for IPv6 communications.


Christopher Y. Metz
Jun-ichiro Itoh

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)