Authentication refused: bad ownership or modes for directory /opt/plcnext

PLCnext Technology & PLCnext Controls
1 
 Authentication refused: bad ownership or modes for directory /opt/plcnext [/code] I get this line in [b]/var/log/auth.log[/b] when I try to log with publickey as user [b]admin[/b] on a PLCnext controller. Login with publickey as user [b]root[/b] works flawlessly. My understanding is, that sshd will not accept public keys if the permissions on the key folder / file are too liberal. [code type="markup"] root@axcf2152:~# ls -al /opt/ total 18 drwxrwxr-x 1 admin plcnext 4096 Jan 17 2019 . drwxr-xr-x 1 root root 4096 Jan 17 2019 .. drwxr-xr-x 3 root root 1024 Mar 9 2018 cifx -rw------- 1 root root 143 Jan 17 2019 fibo.ini drwxrwxr-x 1 admin plcnext 4096 May 9 12:09 plcnext drwxr-xr-x 4 root root 1024 Mar 9 2018 system [/code] Note the liberal permissions on [b]/opt/plcnext[/b] which is the home directory of [b]admin[/b]. Is that a known issue? I am fairly sure, that those permissions are the default ones. For reference a more complete excerpt of [b]/var/log/auth.log[/b] shoing successful root login and failed admin login [code type="markup"] May 12 23:29:24 axcf2152 sshd[8605]: Accepted publickey for root from 100.119.102.104 port 64412 ssh2: RSA SHA256:hYW5CVQMVmyxsvW5Wi2gJJU5cGDSWqX/uzRwzGuxD40 May 12 23:29:24 axcf2152 sshd[8605]: pam_unix(sshd:session): session opened for user root by (uid=0) May 12 23:29:59 axcf2152 sshd[8611]: Authentication refused: bad ownership or modes for directory /opt/plcnext May 12 23:30:07 axcf2152 sshd[8611]: Accepted password for admin from 100.119.102.104 port 64420 ssh2 May 12 23:30:07 axcf2152 sshd[8611]: pam_unix(sshd:session): session opened for user admin by (uid=0)
2

In this Makers Blog post from about two years ago: https://www.plcnext-community.net/en/hn-makers-blog/376-automate-your-development-workflow-with-visual-studio-code.html … the „SSH key based authentication“ section describes something similar to what you are seeing, I think.

3

Thank you for pointing out that article. It holds the solution to my problem and validated my suspicion about the home directory Quote of the relevant fix for reference: su - mkdir -p /home/admin/.ssh chown -R admin:plcnext /home/admin exit chmod 755 /home/admin chmod 700 /home/admin/.ssh touch /home/admin/.ssh/authorized_keys chmod 600 /home/admin/.ssh/authorized_keys