I'm a full time sysadmin at a big company where we have plenty of tools that would be way to much when dealing with a box or two. On my free time I also do some sysadmin for fun - and profit as I learn from it.
When you setup a machine it's clean , packages are up to date and no known security holes are there. But then on gets busy and forgets the machine, which of course gets hacked and is used by non friendly people. On the Debian side of things install and configure apticron and you're done. You'll get an email when things need to be patched - with description of why and command to do it. SO it's quite easy to stay up to date, but that's Debian, how about if you run Centos ?
- First you'll need to configure postfix , I used this guide to do so : https://www.centos.org/docs/5/html/5.1/Deployment_Guide/s3-email-mta-postfix-conf.html
- Second you'll need to get https://github.com/wied03/centos-package-cron/releases from github
- rpm -i centos.... see what dependencies you are missing
- yum install dependencies from the point above
- rerun the install
- centos-package-cron --help and read the github page