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Date:      Tue, 28 May 2002 15:17:55 +0200
From:      Jens Rehsack <rehsack@liwing.de>
To:        Rafter Man <rafter@linuxmail.org>
Cc:        questions@freebsd.org
Subject:   Re: Kernel modules
Message-ID:  <3CF38383.1732BF6C@liwing.de>
References:  <20020528131208.6026.qmail@linuxmail.org>

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1st: reply to all, so that the list can read your answers.

Rafter Man wrote:
> 
> ----- Original Message -----
> From: Jens Rehsack <rehsack@liwing.de>
> > Rafter Man wrote:
> > >
> > > Hi FreeBSD'ers
> > >
> > > From a security point of view, I am not so happy about kernel modules being loaded dynamic.
> >
> > AFAIK linux has many kernel component which are available as module only, too.
> > As in linux you can tell freebsd which kernel modules it has to build (and which not).
> 
> Ok, so I can load the mudules and then set the securelevel, so no more can be loaded?

read http://www.freeBSD.org/handbook/securing-freebsd.html

But this may not useful. Be sure about the consequences of doing that. You never can
set a securelevel back. Maybe jails may more useful if you expect being hacked, because
root of jail != root of machine.

> > > I know you can change the securelevel, so this can't be done, but my question is: In the
> > > future, will all kernel modules also be available trough a static kernel?
> > ??? Some things doesn't make sense in a static kernel. Another point is uptime,
> > it's (as far the interface keeps) more easy reload a kernel module than the kernel :-),
> > an if uptime is important (f.e. 99.999% per year) it's more secure having kernel modules.
> 
> Ok, but it is because I don't want a cracker loading modules like linux support for his exploit
> or bpf for his sniffers.

So (do not compile them and protect /modules) or (set kern.securelevel=1). But remember: you cannot
turn this back. A good local firewall (see http://www.ipfilter.org/) may recommented, or starting
your daemons in a jail with a public ip address and the machine with a private. It much more
difficult hacking a machine with a private ip address, and nearly impossible to do it from jail.
And it's impossible to load a kernel module within a jail (AFAIK)

Jens

> br
> rafter
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