We use the fake IPv4 address 203.0.113.20 for PAM_RHOST in our sessions. libaudit will always do a getaddrinfo() on this address with AI_ADDRCONFIG set. This call will fail on a IPv6 only system and this error can end up in the log:
> resolve_addr: cannot resolve hostname 203.0.113.20
To fix this we would need to use an IPv6 address instead on these systems, and have some logic to determine which to use.
(this bug spawned from bug 5682)