Securing servers

Revision as of 13:56, 21 September 2004

Eventually we'll need sections or subarticles on various different security contexts:

Security in a local user context

(cover common gotchas and SNAFUs concerning local security; ie preventing valid shell users from obtaining privileges they aren't supposed to have or doing damage they shouldn't be able to do. sudo is clearly a must with this one, as is some discussion of running daemons under special user accounts, and the dangers of overusing "nobody" to run daemons. a quick rundown of system files that permissions should be double-checked on, like /etc/passwd, /etc/master.passwd, /etc/group, and the databases associated with them should also be covered.)

Security in an internet context

(firewalls, ssh security gotchas, choosing secure daemons, staying up to date with patches, etc.)

how your server presents itself to the world -- banners, firewall stuff authentication, encryption and you -- switching to blowfish keeping your machine updated -- general, OS and programs keeping your machine updated -- security patches

Security in a local area network context

(probably the shortest of the categories - specific things to watch for in an un-firewalled and extremely-high-bandwidth mostly-trusted environment.)

Security through better logging

(keeping time up to date with ntpd or regularly scheduled ntpdate - and it's worth noting that I've NEVER personally been able to get ntpd to actually update the damn system time, all it seems to do is maintain a drift file for me - but anyway, importance of keeping system time precise down to milliseconds for coordination of system logs with logs at ISPs and other servers involved in network attacks, use of tripwire or built-in daily root emails to monitor for changes in important system files, and also the benefits of either maintaining a separate log server or REGULARLY moving logs off-system to a machine that doesn't trust the server it's getting the logs from one damn bit. this topic may actually need to be moved to its own separate subarticle.)

Of course, each of these sections can themselves spawn entire new subsections / subarticles of their own. There's a reason entire books have been published on computer security! =)

Try to remember, when writing these articles, that "short and sweet" is best, when it comes to a single article. If at all possible, try to limit the scope of any given article to a page or two of text; if you need to refer to something that is going to run a few pages all by itself, consider writing a separate article for that topic and hyperlinking it for people who need it. For example, obviously firewalls need discussion in any internet-context security article, but instead of trying to go over setting one up in the midst of the internet security article itself, it's better to write one article about firewalls and another about the big picture, and just link them.