ssh -v 192.168.1.138
然后会出现很多bug
例如：
debug1: Next authentication method: gssapi-keyex debug1: No valid Key exchange context debug1: Next authentication method: gssapi-with-mic debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_0' not found debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_0' not found debug1: Unspecified GSS failure. Minor code may provide more information debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_0' not found debug1: Next authentication method: publickey debug1: Trying private key: /root/.ssh/identity
查看一下连接时间：
time ssh [email protected] exit real0m4.785s user0m0.014s sys0m0.011s
1、关闭DNS反向解析
在linux中sshd 的服务里是默认开启DNS解析的。会消耗时间，所以需要关闭。
vim /etc/ssh/sshd_config UseDNS no
虽然是被注释掉的，但是默认是yes开启的。
time ssh [email protected] exit real0m3.978s user0m0.016s sys0m0.010s
看实际的连接时间明显减少了很多。说明起了作用！
2、关闭SERVER的认证
在authority过程中，gssapi-with-mic有可能出现很大问题，因此关闭gssapi可以提高很大的速度。
vim /etc/ssh/sshd_config GSSAPIAuthentication no
保存推出
time ssh [email protected] exit real 0m3.832s user 0m0.011s sys 0m0.004s
时间明显减少了很多。基本上就可以正常使用了。