ssh -v 192.168.1.138
然後會出現很多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
查看一下連接時間：
time ssh [email protected] exit real0m4.785s user0m0.014s sys0m0.011s
1、關閉DNS反向解析
在linux中sshd 的服務裏是默認開啓DNS解析的。會消耗時間，所以需要關閉。
vim /etc/ssh/sshd_config UseDNS no
雖然是被註釋掉的，但是默認是yes開啓的。
time ssh [email protected] exit real0m3.978s user0m0.016s sys0m0.010s
看實際的連接時間明顯減少了很多。說明起了作用！
2、關閉SERVER的認證
在authority過程中，gssapi-with-mic有可能出現很大問題，因此關閉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
時間明顯減少了很多。基本上就可以正常使用了。