有人知道高亮线是什么意思吗？
Jun 17 22:20:03 webserver sshd[29519]: Invalid user pi from 197.44.122.204 port 42716
Jun 17 22:20:03 webserver sshd[29519]: input_userauth_request: invalid user pi [preauth]
Jun 17 22:20:03 webserver sshd[29519]: Connection closed by 197.44.122.204 port 42716 [preauth]
Jun 17 22:20:03 webserver sshd[29524]: Invalid user pi from 197.44.122.204 port 42718
Jun 17 22:20:03 webserver sshd[29524]: input_userauth_request: invalid user pi [preauth]
Jun 17 22:20:03 webserver sshd[29524]: Connection closed by 197.44.122.204 port 42718 [preauth]
<---FROM HERE
Jun 17 23:01:24 webserver polkitd[499]: Loading rules from directory /etc/polkit-1/rules.d
Jun 17 23:01:24 webserver polkitd[499]: Loading rules from directory /usr/share/polkit-1/rules.d
Jun 17 23:01:24 webserver polkitd[499]: Finished loading, compiling and executing 2 rules
Jun 17 23:01:24 webserver polkitd[499]: Acquired the name org.freedesktop.PolicyKit1 on the system bus
Jun 17 23:01:27 webserver sshd[887]: Server listening on 0.0.0.0 port 22.
Jun 17 23:01:27 webserver sshd[887]: Server listening on :: port 22.
TO HERE--->
Jun 17 23:21:54 webserver sshd[3355]: Received disconnect from 68.183.80.224 port 42660:11: Bye Bye [preauth]
Jun 17 23:21:54 webserver sshd[3355]: Disconnected from 68.183.80.224 port 42660 [preauth]
Jun 17 23:21:55 webserver sshd[3357]: Invalid user admin from 68.183.80.224 port 44154
Jun 17 23:21:55 webserver sshd[3357]: input_userauth_request: invalid user admin [preauth]
Jun 17 23:21:55 webserver sshd[3357]: Received disconnect from 68.183.80.224 port 44154:11: Bye Bye [preauth]
Jun 17 23:21:55 webserver sshd[3357]: Disconnected from 68.183.80.224 port 44154 [preauth]
Jun 17 23:21:57 webserver sshd[3359]: Invalid user admin from 68.183.80.224 port 45566
Jun 17 23:21:57 webserver sshd[3359]: input_userauth_request: invalid user admin [preauth]
我在这台机器上运行着一个 Web 服务器，上面有 NginX、PHP、MySQL 等……不知何故，从此以后，Web 应用程序无法进入数据库，而我却可以在终端中进入。我只希望这是 MySQL 故障，但我无法从我的安全日志中识别出突出显示的行。有人知道这可能是什么吗？