1.安装 ssh server
sudo apt-get install openssh-server
sudo apt-get install openssh-client
2.查看 ssh 状态
sudo systemctl status ssh
* ssh.service
Loaded: masked (/dev/null; bad)
Active: failed (Result: exit-code) since Fri 2019-04-12 14:45:09 CST; 1min 22s ago
Main PID: 7966 (code=exited, status=255)
Apr 12 14:45:09 yy-pc systemd[1]: Starting OpenBSD Secure Shell server...
Apr 12 14:45:09 y-pc sshd[7966]: error: Bind to port 25 on 0.0.0.0 failed: Address already in use.
Apr 12 14:45:09 y-pc sshd[7966]: error: Bind to port 25 on :: failed: Address already in use.
Apr 12 14:45:09 y-pc sshd[7966]: fatal: Cannot bind any address.
Apr 12 14:45:09 y-pc systemd[1]: ssh.service: Main process exited, code=exited, status=255/n/a
Apr 12 14:45:09 y-pc systemd[1]: ssh.service: Failed with result 'exit-code'.
Apr 12 14:45:09 y-pc systemd[1]: Failed to start OpenBSD Secure Shell server.
3.修改 config 文件
sudo vi /etc/ssh/sshd_config
ssh 默认 22端口
打开注释掉的或者加上
Port 22
4. 重启ssh server
service sshd restart
出现了这个小问题：
Failed to restart ssh.service: Unit ssh.service is masked.
sudo systemctl unmask sshs
service sshd restart
sudo systemctl status ssh
状态正常：
* ssh.service - OpenBSD Secure Shell server
Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2019-04-12 14:48:29 CST; 7min ago
Process: 8276 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
Main PID: 8277 (sshd)
Tasks: 1 (limit: 4915)
CGroup: /system.slice/ssh.service
`-8277 /usr/sbin/sshd -D
Apr 12 14:48:29 y-pc systemd[1]: Starting OpenBSD Secure Shell server...
Apr 12 14:48:29 y-pc sshd[8277]: Server listening on 0.0.0.0 port 22.
Apr 12 14:48:29 y-pc sshd[8277]: Server listening on :: port 22.
Apr 12 14:48:29 y-pc systemd[1]: Started OpenBSD Secure Shell server.
Apr 12 14:48:47 y-pc sshd[8285]: Authentication refused: bad ownership or modes for directory /home/yq
Apr 12 14:48:50 y-pc sshd[8285]: Accepted password for yq from 127.0.0.1 port 60136 ssh2
Apr 12 14:48:50 y-pc sshd[8285]: pam_unix(sshd:session): session opened for user yq by (uid=0)
Apr 12 14:49:02 y-pc sshd[8408]: Accepted password for yq from 192.168.20.194 port 1089 ssh2
Apr 12 14:49:02 y-pc sshd[8408]: pam_unix(sshd:session): session opened for user yq by (uid=0)
