Linux无法登陆，var目录权限修改导致SSH失败

2021-08-14 00:21:21

1.问题说明

Linux远程服务器突然无法SSH登录了，

登陆报错：

ssh_exchange_identification: read: Connection reset by peer。

2.问题原因

最近安装MySQL数据库，

安装过程中修改了var目录的权限，

偷懒直接chmod -R 777 /var。

3.解决办法

将SSH相关文件的权限改回来，

确保权限为755，属主为root:root。

3.1.查看sshd状态

service sshd status

Redirecting to /bin/systemctl status sshd.service

● sshd.service - OpenSSH server daemon

   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)

   Active: active (running) since 二 2019-04-09 23:36:09 CST; 18h ago

     Docs: man:sshd(8)

           man:sshd_config(5)

  Process: 1357 ExecStart=/usr/sbin/sshd $OPTIONS (code=exited, status=0/SUCCESS)

 Main PID: 1358 (sshd)

   CGroup: /system.slice/sshd.service

           ├─ 1358 /usr/sbin/sshd

           ├─20443 sshd: root@pts/1

           ├─20445 sshd: root@notty

           ├─20447 /usr/libexec/openssh/sftp-server

           ├─20594 -bash

           ├─23794 sshd: mysql [priv]

           ├─23796 sshd: mysql@pts/0

           ├─23797 sshd: mysql [priv]

           ├─23799 sshd: mysql@notty

           ├─23800 /usr/libexec/openssh/sftp-server

           ├─23991 -bash

           ├─25381 vim /etc/init.d/mysqld

           └─25739 /bin/systemctl status sshd.service

4月 10 17:59:47 dap229-156 sshd[21516]: pam_unix(sshd:session): session closed for user mysql

4月 10 18:00:05 dap229-156 sshd[23794]: Accepted password for mysql from 10.43.163.30 port 54797 ssh2

4月 10 18:00:05 dap229-156 sshd[23794]: pam_unix(sshd:session): session opened for user mysql by (uid=0)

4月 10 18:00:05 dap229-156 sshd[23797]: Accepted password for mysql from 10.43.163.30 port 54798 ssh2

4月 10 18:00:05 dap229-156 sshd[23797]: pam_unix(sshd:session): session opened for user mysql by (uid=0)

4月 10 18:26:00 dap229-156 sshd[25579]: fatal: /var/empty/sshd must be owned by root and not group or world-writable.

4月 10 18:26:12 dap229-156 sshd[25580]: fatal: /var/empty/sshd must be owned by root and not group or world-writable.

4月 10 18:26:29 dap229-156 sshd[25581]: fatal: /var/empty/sshd must be owned by root and not group or world-writable.

4月 10 18:26:46 dap229-156 sshd[25590]: fatal: /var/empty/sshd must be owned by root and not group or world-writable.

4月 10 18:30:11 dap229-156 sshd[25622]: fatal: /var/empty/sshd must be owned by root and not group or world-writable.

可以看到报错信息，

提示/var/empty/sshd必须属于root用户，

且所有其他用户都不能有写权限，

所以文件权限可以改为755。

3.2.修复文件权限

chmod 755 /var/empty/sshd

如果属主不对，还需要修改属主：

chown root:root /var/empty/sshd

3.3.重启sshd服务

service sshd restart

3.4.再次查看sshd状态