查看端口 22 是否 listening

root@kali:~# netstat -an | grep :22
root@kali:~#

查看 ssh service状态

root@kali:~# service ssh status
[FAIL] sshd is not running … failed!
root@kali:~#

启动ssh service

root@kali:~# service ssh start
[ ok ] Starting OpenBSD Secure Shell server: sshd.
root@kali:~#

再次查看ssh status

● ssh.service - OpenBSD Secure Shell server
   Loaded: loaded (/lib/systemd/system/ssh.service; disabled; vendor preset: di>
   Active: active (running) since Wed 2020-09-16 22:46:01 EDT; 6min ago
     Docs: man:sshd(8)
           man:sshd_config(5)
  Process: 1913 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
 Main PID: 1914 (sshd)
    Tasks: 1 (limit: 2300)
   Memory: 3.0M
   CGroup: /system.slice/ssh.service
           └─1914 /usr/sbin/sshd -D

再次检查22 是否处于 listening

root@kali:~# netstat -an | grep :22
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp6       0      0 :::22                   :::*                    LISTEN
root@kali:~#
root@kali:~/Desktop#

设置允许root 用户登录
先备份配置文件

cd /etc/ssh/
cp sshd_config sshd_config.bak

修改配置文件 sshd_config

vim sshd_config

# Authentication:
#LoginGraceTime 2m
#PermitRootLogin prohibit-password
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

添加一行PermitRootLogin yes

# Authentication:
PermitRootLogin yes
#LoginGraceTime 2m
#PermitRootLogin prohibit-password
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

重启ssh服务
service ssh start
然后大功告成