utility to set IPv6 address preferences

 ipv6pref provides a utility that preloads a library and
 allows users to control the use of IPv6 privacy extensions.
 .
 For longrunning tasks it may be undesirable to use the periodically
 changing and random addresses; using the supplied utility,
 the kernel can be instructed whether to prefer the temporary addresses
 or stick to the static ones when opening sockets for a specific program.