Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Login Access Control

The /etc/security/access.conf file specifies (user/group, host), (user/group, network/netmask) or (user/group, tty) combinations for which a login will be either accepted or refused.

https://www.poftut.com/access-conf-security-configuration-linux-unix/

https://linux.die.net/man/5/access.conf

Sudo Access Control

The /etc/sudoers file controls who can run what commands as what users on what machines and can also control special things such as whether you need a password for particular commands. The file is composed of aliases (basically variables) and user specifications (which control who can run what). However, it is suggested you never touch the file /etc/sudoers directly (even not via the comamnd visudo). You might screw up all sudo users if you damage the format of the file. The right way to grant a user sudo access is to add the user to the sudo group. Please refer to Add Users to a Group in Linux for more details on how to add user to a group.

https://medium.com/@viraj.khatavkar/understanding-the-sudoers-file-8d71961b28ac

https://help.ubuntu.com/community/Sudoers