Date: Wed, 11 Feb 2004 14:12:46 +0100 (CET) From: roberto@redix.it To: freebsd-security@freebsd.org Subject: Re: Question about securelevel Message-ID: <1171.192.168.0.77.1076505166.squirrel@mail.redix.it>
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I want to discuss securelevel and whether it's a good or bad thing. Now, I do not need help to get it working (but never say never ...). I'll try to explain my idea. Suppose I'm trying to setup a packet-filtering firewall based on FreeBSD, and I want to harden it (I heard about TrustedBSD, but here I want to speach about securelevel). I made the assumption that the console (of my BSD) is in a safe place, so I can exclude any hack from it. It should be the only place where the administrator can access the O.S. with securelevel disabled (i.e.=0, by means of a single user mode). In normal condition, O.S. is running on securelevel=3 so nobody can: - kernel module connot be loaded or unloaded; - packet filtering rules connot be altered; - /dev/mem and kmem cannot be write; - immutable and sys flags cannot be turned off; In addition (this is my idea), suppose to configured the root filesystem read-only and there is no way to change this (remount it rw) when securelevel is == 3. Could this configuration be considered secure, according to you? There are any weakness of securelevel still present? Any comments are welcome... Regards, Roberto
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