Tectia Server for IBM z/OS can operate using IPv4 (inet) addressing, IPv6 (inet6), or both (any), as specified by the sshd2_config keyword AddressFamily:

AddressFamily                   (inet|inet6|any)

The default is inet.

The ListenAddress keyword can be specified several times. The value is an IPv4 address or an IPv6 address; either may be followed by an optional port number. If the configuration variable is not specified, sshd2 listens on the IPv4 unspecified address (0.0.0.0) or the IPv6 unspecified address (::) or both depending on the value of AddressFamily.

sshd2 will open listener sockets in the order the ListenAddress configuration variables occur in the configuration file. sshd2 will not start unless it is able to open at least one socket. sshd2 will not start if any of the sockets cannot be opened or does not belong to the address family specified in AddressFamily or by the -4 or -6 command line option.