默认情况下

/etc/ssh/ssh_config文件里的GSSAPIAuthentication被设置成了yes,这样会导致一个连接_kerberos.<hostname>的DNS请求。
除非对外界的请求被中断，否则ssh的会话直到DNS请求超时才会继续下去。不是一个什么问题，
只是会对内网访问造成一定的痛苦。

所以解决的办法是把这个 GSSAPIAuthentication默认设置成 no就可以了。

ssh_config and GSSAPIAuthentication

The default Fedora ssh_config file comes with GSSAPIAuthentication set
to "yes". This causes a DNS query in an attempt to resolve
_kerberos.<hostname> whenever ssh is invoked. During periods when
connectivity to the outside world is interrupted for whatever reason,
the ssh session won't proceed until the DNS query times out. Not really
a problem, just more of an annoyance when trying to ssh to another
machine on the LAN.

Is there a reason why the default ssh_config comes with
GSSAPIAuthentication set to yes?

Thanks,
Jay