Connecting to 172.17.11.147:22...
Could not connect to '172.17.11.147' (port 22): Connection failed.

Type `help' to learn how to use Xshell prompt.
Xshell:\>

先關掉防火牆重啟看看

systemctl disable firewalld

systemctl stop firewalld

systemctl status firewalld

出现这种情况的原因：
1.服务器端防火墙关闭了22端口，没有开启ssh服务；
2.没有安装ssh；
解决原因1：使用netstat,查看是否启动shh服务；
开启ssh服务：service sshd start
关闭ssh服务：service sshd stop
重启ssh服务：servcie sshd restart
SSH服务开机自动启动：chkconfig sshd on
取消开机自启动:chkconfig sshd off
开启服务后，检查服务状态：service sshd status
解决原因2：安装ssh：
yum install openssh-server

沒用

service ssh status

sshd.service - OpenSSH server daemon
   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled)
   Active: activating (auto-restart) (Result: exit-code) since Thu 2016-05-05 03:30:48 UTC; 2s ago
  Process: 10938 ExecReload=/bin/kill -HUP $MAINPID (code=exited, status=0/SUCCESS)
  Process: 10944 ExecStart=/usr/sbin/sshd -D $OPTIONS (code=exited, status=255)
 Main PID: 10944 (code=exited, status=255)

May 05 03:30:48 ixnetwork-uk1 systemd[1]: sshd.service: main process exited, code=exited, status=255/n/a
May 05 03:30:48 ixnetwork-uk1 systemd[1]: Unit sshd.service entered failed state.