On 1/2/2012 9:18 AM, Les Mikesell wrote: > On Mon, Jan 2, 2012 at 6:03 AM, Bennett Haselton<bennett at peacefire.org> wrote: >> I tried SELinux but it broke so much needed functionality on the server >> that it was not an option. > Pretty much all of the stock programs work with SELinux, so this by > itself implies that you are running 3rd party or local apps that have > write access in non-standard places. Which is a good start at what > you need to break in. What apps are those (i.e. the ones that > SELinux would have broken) and if they are open source, have those > projects updated the app or the underlying language(s)/libraries since > you have? So here's a perfect example. I installed squid on one machine and changed it to listen to a non-standard port instead of 3128. It turns out that SELinux blocks this. (Which I still don't see the reasoning behind. Why would it be any less secure to run a service on a non-standard port? A lot of sources say it's *more* secure to run services on a non-standard port if you don't want people poking around! In general I don't think it's any more secure to run a service on a non-standard port -- all it buys you is time, as it's trivial for an attacker to scan all your ports, especially with a botnet -- but even if it's not more secure, it certainly shouldn't be *less* secure.) But here's the real problem. Since I didn't know it was caused by SELinux, all the cache.log file said was: 2012/01/02 17:40:40| commBind: Cannot bind socket FD 13 to *:[portnum redacted]: (13) Permission denied Nothing indicating why. Even worse, if you Google +squid +"cannot bind socket" +"permission denied" *none* of the first ten pages that come up, mention SELinux as a possible source of the problem. (One FAQ mentions SELinux but only as the source of a different problem.) All they do is recommend other workarounds, each of which takes time to test out, and may have other side-effects. In other words, when SELinux causes a problem, it can take hours or days to find out that SELinux is the cause -- and even then you're not done, because you have to figure out a workaround if you want to fix the problem while keeping SELinux turned on. -Bennett