The problem is I can not sign in the Webmin panel.  I did a lot of searches and finally got the solution.

Here is the situation:

  • Oracle VM Free Tier.  I selected the Image: CentOS-7-2020.04.21-0.
  • For CentOS, SSH public key connection.  The user is OPC  when I try to ssh to it.
  • Then I add a new user and add it to the group wheel.  the username is admin.
  • Based on the How To Create a Sudo User on CentOS on DigitalOcean.
  • I followed the installation guide on the Webmin support page. The ports 10000 to 10010 are opened.
  • In the browser, I can see the login page.  But can not log in with the new user, admin.
  • Check the error log of webmin at /var/webmin/miniserv.error
    The error message is missing  Perl module Authen::PAM 
  • Then I install Authen::PAM in the ssh window.
  • Try to login again. Still can not log in.
  • I restart the server, and still can not log in.

The real solution is below:

/usr/libexec/webmin/changepass.pl /etc/webmin username password

Replace username by root, and with my own password.

After this command, I can log in the Webmin as root.

See the basic information of this VM.

Features:

  • AMD EPYC 7551 32-Core Processor, 2 Cores
  • 1GB RAM memory
  • 40GB Storage
  • CentOS 7.8
  • Webmin 1.941