[root@localhost wj]# rpm -qa | grep ssh

libssh2-1.4.2-1.el6.i686

openssh-askpass-5.3p1-94.el6.i686

openssh-server-5.3p1-94.el6.i686

openssh-clients-5.3p1-94.el6.i686

openssh-5.3p1-94.el6.i686

[root@localhost wj]# service sshd status

openssh-daemon (pid  1634) 正在运行...

[root@localhost wj]# 

[root@localhost wj]# ssh root@192.168.0.119

The authenticity of host '192.168.0.119 (192.168.0.119)' can't be established.

RSA key fingerprint is 36:20:c9:ab:88:1f:47:74:1b:f1:d7:47:55:e0:14:7c.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.0.119' (RSA) to the list of known hosts.

root@192.168.0.119's password: 

Last login: Fri Aug 10 14:57:45 2018

already login

[root@localhost ~]# exit

logout

Connection to 192.168.0.119 closed.

[root@localhost wj]# gedit /etc/ssh/sshd_config 

PermitRootLogin no    //这里默认是yes，而且已经被注释掉了。取消注释，改为no

[root@localhost wj]# service sshd restart           //重启服务

停止sshd：                                               [确定]

正在启动sshd：                                            [确定]

[root@localhost wj]# 

[root@localhost wj]# ssh root@192.168.0.119

root@192.168.0.119's password: 

Permission denied, please try again.

[root@localhost wj]# gedit /etc/ssh/sshd_config 

AllowUsers david    //允许david登录

[root@localhost wj]# service sshd restart           //重启服务

停止sshd：                                               [确定]

正在启动sshd：                                            [确定]

[root@localhost wj]#

[root@localhost wj]# ssh weijie@192.168.0.119

weijie@192.168.0.119's password: 

Permission denied, please try again.

[root@localhost wj]# ssh david@192.168.0.119

david@192.168.0.119's password: 

Last login: Wed Aug 15 17:12:59 2018 from 192.168.0.112

already login