sshd VerifyReverseMapping fails for IPv4 connections to machines with IPv6 addresses.
The code in sshd which verifies the reverse mapping for a client IP address (VerifyReverseMapping yes in sshd_config) fails if the system has an IPv6 address. The client IP address is returned as an IPv4 mapped address which is subsequently converted to a plain IPv4 address. When the forward mapping is performed to check the IP address, the plain IPv4 address is passed along with what is now the wrong address family.
returning 0 (::ffff:192.168.1.1)
returning 0 (test.citrus-it.net)
returning 7 (EAI_NODATA)
get_remote_hostname() returning "192.168.1.1"