I've been working on my linux firewall off and on for some time now,
and last night I wasd thinking about a very small, stable and as secure
as possible linux distribution especially for firewalls or other security
My thinking is this:
1.) a recent kernel, stripped down to the bare essentials.
2.) support for multiple ethernet cards or PPP
3.) s/key for password authentication
4.) no compiler, utilities, editor, or man pages except the true essentials.
5.) statically linked binaries
6.) tripwire-hashed binaries with md5 sums kept on read-only floppy
7.) no user accounts.
8.) safe ftp and mail servers.
9.) ipfwadm set up to be as secure as possible.
10.) copyright permitting, maybe the TIS firewall toolkit daemons.
11.) removal of all suid programs (with no user accounts, this should work)
12.) check and recheck sources for ages-old known holes.
13.) tcp wrappers on all services
14.) totally buildable from source with a ``make world''
Ideally, this distribution would err on the side of paranoia, and would
be as secure as humanly possible right out of the box. I don't see this as
a user-level distribution, more as a collection of security enhancements
for the administrator who is going to put together a firewall and wants to
make it as secure as he/she can.
Any thoughts? Has anyone already attempted this?
This is very preliminary, and I can't even guarantee I could do this myself
because of time and code-hacking stupidity constraints.