Address maps to but this does not map back to the address

机器A ssh到机器B时报错：
Address x.x.x.x  maps to x.x.x.x.ha.cnc, but this does not map back to the address – POSSIBLE BREAK-IN ATTEMPT!

其实这并不影响到登录，只是总报这个心烦，如下设置就可以不让它报错。
到机器B上  
sed -i 's/GSSAPIAuthentication yes/GSSAPIAuthentication no/g'  /etc/ssh/sshd_config  &&　/etc/init.d/sshd restart

这个操作的意思是，在机器B上把/etc/ssh/sshd_config文件中的‘GSSAPIAuthentication yes’ 改成 ‘GSSAPIAuthentication no’