The Open Group IPv6 Support in UNIX® Sockets


XNET has enhanced the Open Group Networking Services Technical Standard (XNS), which how now been merged into the Single UNIX Specification Version 3, to support IPv6.

The Single UNIX Specification Version3, incorporating changes for IPv6, is on the web.

The new generation Internet Protocol, IPv6, became necessary because the address space of the version in common use (version 4) was inadequate to sustain the projected growth of the Internet. The standards for it were developed by the IETF ipng working group.

As well as a massively bigger address space, IPv6 is designed to provide greater manageability and security. There are a number of features that aid configuration and operation of IPv6 nodes and sites in the modern Internet environment. The associated standards being developed by the IETF ipsec working group will provide for authentication, integrity and confidentiality.

Further information on IPv6 and on how it is being deployed can be found at

The Open Group Networking Services are now part of the Single UNIX Specification maintained by the Base Working Group.

The main changes for IPv6 are:
  • Man pages for the new functions if_freenameindex(), if_indextoname(), if_nameindex() and if_nametoindex() have been added to Chapter 8, Sockets Interfaces.
  • New functions getipnodebyaddr() and getipnodebyname() have been added to the endhostent() man page in Chapter 10, IP Address Resolution Interfaces.
  • Man pages for the new functions inet_ntop() and inet_pton() have been added to Chapter 10, IP Address Resolution Interfaces.
  • A new Appendix Q, Use of Internet Protocols over Sockets Based on IPv6 has been added.

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