openssl not work with ipv6 only hosts. % openssl s_client -connect ipv6.google.com:443 -tls1 -tlsextdebug -status gethostbyname failure connect:errno=0 % ncat -6 --ssl -v ipv6.google.com 443 Ncat: Version 6.47 ( http://nmap.org/ncat ) Ncat: SSL connection to 2a00:1450:4013:c01::66:443. Google Inc Ncat: SHA-1 fingerprint: 564B C539 C2A9 5675 EA9E 2803 D2AA 0E74 59B9 7AC0 OpenBSD have long time ago man openssl .... -6 Specify that s_client should attempt connections using IPv6 only. .... FreeBSD only wiki suggestion? In the wiki have https://wiki.freebsd.org/IPv6TODO#openssl_s_client (add WIP with GSoC2012 )