一、问题：
[C:\~]$
Connecting to 121.X.X.X:22...
Could not connect to '121.X.X.X' (port 9670): Connection failed.
Type `help' to learn how to use Xshell prompt.
### 测试云服务器ssh 端口 有没有通
root@master1:~# telnet 121.X.X.X 22
Trying 121.X.X.X...
telnet: Unable to connect to remote host: No route to host
发现没有通
二、解决
2.1 查看安全组中有没有开放22端口
发现22 端口是开着的
2.2 用云服务器的VNC方式连接云服务器，看看ssh 服务是不是挂了
2.3 总结：
发现端口是开着的，服务也是可用的，但是就是telnet 不通，也连不上。
1.怀疑是防火墙没关的原因,后面一查，果然：
[root@VMXXXXX ~]# systemctl status firewalld
2.防火墙关闭就可以连了
[root@VMXXXXX ~]# systemctl stopfirewalld
###用其他机器测试一下端口 ,通了，
root@master1:~# telnet 121.X.X.X 22
Trying 121.X.X.X...
Connected to 121.X.X.X.
Escape character is '^]'.
SSH-2.0-OpenSSH_8.0
^C
Connection closed by foreign host.
###xshell 也可以连接了
Connecting to 121.X.X.X:22...
Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.
WARNING! The remote SSH server rejected X11 forwarding request.
Activate the web console with: systemctl enable --now cockpit.socket
Last login: Mon May 9 21:06:22 2022 from
[root@VMXXXXX ~]#
