How dangerous is it to *not* have SELinux enabled?

[magnublm]

I come from a Windows world. I get paid to support NT servers, and have since 1994. My niche is anti-virus, unfortunately. I loathe and detest Windows*.* At home I have a Fedora server because Linux simply rocks. I do not, however, have SELinux enabled. Since this is Linux, anyway, and less prone to attacks and viruses than Windows, how (un)secure am I? (I don't have it enabled because when I did a yum update and updated it, after rebooting I get "Invalid lines ### in SELinux" when the system comes up; then I can't access the Internet at all. That's beside the point. Although I would like that fixed [But that's not for this post.]) How "secure" are Fedora boxes without SELinux enabled? Aren't most attacks aimed at the Windows world? Or am I ignorant? (I prefer "unlearned", in this case.) How do you have your server setup: with or without it? I know good hardware (firewalls, routers and proper rules) in front of your server(s) makes a difference, but put that aside for the moment and discuss with me how safe not having SELinux enabled is. Thanks.

[sailor]

I am not running a server so I always disable SELinux...it has issues with java and is a PITA to configure. For a home desktop I don't see the need for it. On a server it might be worth the extra security features.
A linux server is more secure for various reasons. As you said, there isn't many viri or exploits aimed at linux boxes. Linux uses a permissions system to guard access to critical funcitons.
Fedora has a firewall built in, so it a good idea to read up on iptables and sys administration to make sure that there are no holes. That done, I would think your server would still be quite secure.

[SlowJet]

All my Luinuxes wear SELinux or they wear nothing at all.

Kids, do not be hardheaded. Use SELinux.
The NSA and Red Hat and IBM are using SELinux for a reason.

Desktop machines at the end user need it the most.
I am running FC5 development fully updated and all SELinux is on and working.
I have never had a crash.
FC4 fully updated as of now will run as smooth as glass.

SJ

P.S. SELinux has nothing to do with the Internet or file pemissions. Those are other layers of security older than the trees.

[sailor]

n NSA's words:
"The Security-enhanced Linux features are designed to enforce the separation of information based on confidentiality and integrity requirements. They are designed for preventing processes from reading data and programs, tampering with data and programs, bypassing application security mechanisms, executing untrustworthy programs, or interfering with other processes in violation of the system security policy. They also help to confine the potential damage that can be caused by malicious or flawed programs. They should ualso be useful for enabling a single system to be used by users with differing security authorizations to access multiple kinds of information with differing security requirements without compromising those security requirements."

It deals with varying security levels for different users, as well as protecting the system from
malicious programs, unsecure applications and preventing those applications from violating security policies. In a nutshell it is a more advanced implementation of permissions for both users and applications.

[imdeemvp]

This is my opinion ONLY:

Since selinux came out and it was buggy from the start I dropped it! I can only handle testing so much beta in fedora and did not want ot bear the burden of selinux.

I've heard other users never having an issue and vice versa. If you want to use it is a matter of choice.

[Finalzone]

Originally Posted by imdeemvp

This is my opinion ONLY:

Since selinux came out and it was buggy from the start I dropped it! I can only handle testing so much beta in fedora and did not want ot bear the burden of selinux.

I've heard other users never having an issue and vice versa. If you want to use it is a matter of choice.

The difference is FC2 uses Strict Policy which explain why many programs couldn't work. Since FC3, SELinux uses Targeted Policies so it restrict specific applications. Therefore, leaving SELinux won't impact desktop functionality.

[elliss]

The main function of the current default ("targetted") SELinux mode is really to reduce the severity of any exploits by restricting the ability of network services to access other parts of the system. If you run a public Website on an Apache server it has to be available to everybody on the Internet, so the firewall cannot block requests on port 80, even if they are from automated attack scripts. The SELinux policy on Fedora and RHEL 4 will prevent a compromised Apache service from tampering with anything other than the files that Apache normally has access to.

SELinux potentially has other uses, especially when combined with Xen and Stateless Linux, so it's important to have it integrated into the base system. Personally, I leave it switched on, and the only problem I've encountered is having to use the fixfiles utility after setting up shared directories in non-standard locations.

[Jman]

Fedora without selinux is like the Titanic without it's sealable compartments. The ship was still strong without them, but the seperation was supposed to enable it to take on water in several compartments and still float.

In a similar way selinux isolates system services and other things from each other so that if one is compromised it can be isolated.

Note, however, that the Titanic sank. selinux is not bulletproof, and is no substitute for a firewall (analagous to the steel walls of the ship).