Rules for configuring the IBM-supplied listener for IPv6

The following rules apply when configuring the IBM-supplied listener for IPv6:

You must enable the z/OS® system that the IPv6 listener uses for IPv6. See z/OS Communications Server: IP Configuration Reference for information on IPv6 system configuration.
Because an IPv6 enabled listener uses the GIVESOCKET API function to give an IPv6 socket to a child server transaction, you must enable that child server transaction program to use IPv6 sockets. This requires that all API functions that use a socket address structure be changed to use the larger IPv6 socket address structure. See C language application programming or Sockets extended API for more information.
If the listener gives the accepted socket to the child server program, the child server program must be able to take that socket. If the listener is defined as an INET6 listener, the EBADF errno is issued if the child server's TAKESOCKET is AF_INET. If the listener is defined as an INET listener, the EBADF errno is issued if the child server's TAKESOCKET is AF_INET6.

The Security/Transaction Exit program allows the user to examine and change certain pieces of data that are passed to the child server program by the listener.

Table 1 illustrates the listener configuration in contrast with the connected client's address family and indicates the contents of the IPv4 and IPv6 IP address fields presented to the Security/Transaction Exit.

Table 1. Security/Transaction Exit program information fields
Listener's AF configuration	Connected Client's AF	Exit's Address Family	Exit's Client's IPv4 address	Exit's Client's IPv6 address	Exit's Listener's IPv4 address	Exit's Listener's IPv6 address
not specified	AF_INET	AF_INET	IPv4 addr	zeros	IPv4 addr	zeros
AF_INET	AF_INET	AF_INET	IPv4 addr	zeros	IPv4 addr	zeros
AF_INET6	AF_INET	AF_INET6	zeros	IPv4 mapped IPv6 addr	zeros	IPv4 mapped IPv6 addr
AF_INET6	AF_INET6	AF_INET6	zeros	IPv6 addr	zeros	IPv6 addr