While I am in the process of documenting each and every possible method of blocking or allowing a local user or remote user access from a service, I figured that I might as well drop a small little post out there on the subject of cron.allow and cron.deny.  First off you should know that allowing and blocking access to cron is very, very easy as you only need to know two files and there is not a special

Basically you are working with two files, the /etc/cron.allow and /etc/cron.deny.

Users are allowed to run cronjobs if:

• if the user’s name appears in /etc/cron.d/cron.allow.

• if  /etc/cron/cron.allow does not exist and the user’s name is not in /etc/cron/cron.deny.

Users are blocked from running cronjobs if:

• /etc/cron/cron.allow exists and the user’s name is not in it.

• /etc/cron/cron.allow does not exist and user’s name is in /etc/cron/cron.deny.

Note that the rules for allow and deny apply to root only if the allow/deny files exist.

Below is what a blocked user will see if they try to create a crontab entry

$ crontab -l
You (fatmin( are not allowed to use this program (crontab)
See crontab(1) for more information