ssh连接缓慢解决方法

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 root@192.168.1.138 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 root@192.168.1.138 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

time ssh root@192.168.1.138 exit
real 0m3.832s
user 0m0.011s
sys  0m0.004s