Sudo and passwords configuration

Sudo

Concepts

• With sudo you can specify which users may run which commands on a given host, and as a given user. You can configure sudo so that it does, or does not, prompt for a password.
• If you wish to run a command as a different user (if you are root for example, and wish to launch as tomcat), pass the -u user parameter to sudo.
• You can also run a command as a different group with the -g flag. This is only available since sudo-1.7.0.

Main configuration file

• The configuration is done via /etc/sudoers.
• A single line looks like:

elvanor ALL = (tomcat) NOPASSWD: /usr/bin/gimp-console, /usr/bin/convert

This would mean that the user elvanor may run, as the user tomcat, the commands gimp-console and convert on any host (the first ALL represent the hosts). He won't be asked for a password.

• To configure the groups that the command may be run as, you need to add a second list after a semi-colon in the proper place, like this:

%shoopz ALL = (:shoopz) NOPASSWD: /usr/local/bin/unison

Environment variables

• Normally, sudo passes to the processes it creates a clean environment (eg, no environment variables from the parent shell). However this behavior can be modified via some flags (env_reset, env_keep etc). env_keep is specially interesting as it allows a specified environment variable to be passed to the process sudo creates.

Passwords

• Using passwd will prevent you to choose a "weak" password by default on Gentoo. Change the /etc/security/passwdqc.conf file (with enforce=none line) to be able to circumvent this constraint.