Linux系统无法登录的原因是什么？
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本文共计760个文字，预计阅读时间需要4分钟。
相关专题：
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
var目录的权限不正确
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。
这里可以使用vps服务器的svn功能，进行登录系统，vps提供商都会提供vnc登录功能。
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.
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
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 三 2019-04-10 18:35:01 CST; 3s ago Docs: man:sshd(8) man:sshd_config(5) Process: 25768 ExecStart=/usr/sbin/sshd $OPTIONS (code=exited, status=0/SUCCESS) Main PID: 25769 (sshd) CGroup: /system.slice/sshd.service ├─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 ├─25769 /usr/sbin/sshd └─25770 /bin/systemctl status sshd.service 4月 10 18:35:01 dap229-156 systemd[1]: Starting OpenSSH server daemon... 4月 10 18:35:01 dap229-156 systemd[1]: PID file /var/run/sshd.pid not readable (yet?) after start. 4月 10 18:35:01 dap229-156 sshd[25769]: Server listening on 0.0.0.0 port 22. 4月 10 18:35:01 dap229-156 sshd[25769]: Server listening on :: port 22. 4月 10 18:35:01 dap229-156 systemd[1]: Started OpenSSH server daemon.
这个时候检查没有错误了，服务器可以SSH登录了，
至此问题解决。
推荐：linux系统教程
本文共计760个文字，预计阅读时间需要4分钟。
相关专题：
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
var目录的权限不正确
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。
这里可以使用vps服务器的svn功能，进行登录系统，vps提供商都会提供vnc登录功能。
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.
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
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 三 2019-04-10 18:35:01 CST; 3s ago Docs: man:sshd(8) man:sshd_config(5) Process: 25768 ExecStart=/usr/sbin/sshd $OPTIONS (code=exited, status=0/SUCCESS) Main PID: 25769 (sshd) CGroup: /system.slice/sshd.service ├─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 ├─25769 /usr/sbin/sshd └─25770 /bin/systemctl status sshd.service 4月 10 18:35:01 dap229-156 systemd[1]: Starting OpenSSH server daemon... 4月 10 18:35:01 dap229-156 systemd[1]: PID file /var/run/sshd.pid not readable (yet?) after start. 4月 10 18:35:01 dap229-156 sshd[25769]: Server listening on 0.0.0.0 port 22. 4月 10 18:35:01 dap229-156 sshd[25769]: Server listening on :: port 22. 4月 10 18:35:01 dap229-156 systemd[1]: Started OpenSSH server daemon.
这个时候检查没有错误了，服务器可以SSH登录了，
至此问题解决。
推荐：linux系统教程