If you use IPv6 and TCP Wrapper for SSH access control, then don’t forget to add your IPv6 host to hosts.allow file. IPv6 address must be written in a bracket [fe80:0:0:0:200:f8ff:fe21:67cf]. Example of hosts.allow file is something like that:
sshd,sshdfwd-X11: [fe80:0:0:0:200:f8ff:fe21:67cf]