4
4
- Have your cake and eat it too!
6
You know how it is. You've heard of it happening. The Man comes
7
and takes away your servers, your friends' servers, the servers of
6
You know how it is. You’ve heard of it happening. The Man comes
7
and takes away your servers, your friends’ servers, the servers of
8
8
everybody in the same hosting facility. The servers of their
9
neighbors, and their neighbors' friends. The servers of people who
10
owe them money. And like *that*, they're gone. And you doubt
11
you'll ever see them again.
9
neighbors, and their neighbors’ friends. The servers of people who
10
owe them money. And like *that*, they’re gone. And you doubt
11
you’ll ever see them again.
13
13
That is why your servers have encrypted root file systems. However,
14
there's a downside. There's no going around it: rebooting is a
14
there’s a downside. There’s no going around it: rebooting is a
15
15
pain. Dragging out that rarely-used keyboard and screen and
16
16
unraveling cables behind your servers to plug them in to type in
17
17
that password is messy, especially if you have many servers. There
23
23
have to be on hand and manually type in the password at boot time.
24
24
Otherwise the server just sits there, waiting for a password.
26
Wouldn't it be great if you could have the security of encrypted
26
Wouldn’t it be great if you could have the security of encrypted
27
27
root file systems and still have servers that could boot up
28
28
automatically if there was a short power outage while you were
29
29
asleep? That you could reboot at will, without having someone run
50
50
Now, of course the initial RAM disk image is not on the encrypted
51
51
root file system, so anyone who had physical access could take the
52
server offline and read the disk with their own tools to get the
53
authentication keys used by a client. *But*, by then the Mandos
54
server should notice that the original server has been offline for
55
too long, and will no longer give out the encrypted key. The timing
56
here is the only real weak point, and the method, frequency and
57
timeout of the server’s checking can be adjusted to any desired
52
Mandos client computer offline and read the disk with their own
53
tools to get the authentication keys used by a client. *But*, by
54
then the Mandos server should notice that the original server has
55
been offline for too long, and will no longer give out the encrypted
56
key. The timing here is the only real weak point, and the method,
57
frequency and timeout of the server’s checking can be adjusted to
58
any desired level of paranoia
60
60
(The encrypted keys on the Mandos server is on its normal file
61
61
system, so those are safe, provided the root file system of *that*
69
69
to do. An attacker would have to physically disassemble the client
70
70
computer, extract the key from the initial RAM disk image, and then
71
71
connect to a *still online* Mandos server to get the encrypted key,
72
all *before* the Mandos server timeout kicks in and the Mandos
73
server refuses to give out the key to anyone.
72
and do all this *before* the Mandos server timeout kicks in and the
73
Mandos server refuses to give out the key to anyone.
75
Now, as the typical SOP seems to be to barge in and turn off and
76
grab *all* computers, to maybe look at them months later, this is
77
not likely. If someone does that, the whole system *will* lock
75
Now, as the typical procedure seems to be to barge in and turn off
76
and grab *all* computers, to maybe look at them months later, this
77
is not likely. If someone does that, the whole system *will* lock
78
78
itself up completely, since Mandos servers are no longer running.
80
For sophisticated attackers who *could* do such a thing, *and* had
81
physical access to the server for enough time, it would be simpler
82
to get a key for an encrypted file system by using hardware memory
83
scanners and reading it right off the memory bus.
80
For sophisticated attackers who *could* do the clever thing, *and*
81
had physical access to the server for enough time, it would be
82
simpler to get a key for an encrypted file system by using hardware
83
memory scanners and reading it right off the memory bus.
86
86
Nope, the network stuff is all done over TLS, which provides
125
125
just as well open your servers and read the file system keys right
126
126
off the memory by running wires to the memory bus.
128
What this system is designed to protect against is *not* such
129
determined, focused, and competent attacks, but against the early
130
morning knock on your door and the sudden absence of all the servers
131
in your server room. Which it does nicely.
128
What Mandos is designed to protect against is *not* such determined,
129
focused, and competent attacks, but against the early morning knock
130
on your door and the sudden absence of all the servers in your
131
server room. Which it does nicely.
135
Copyright © 2008 Teddy Hogeborn
140
This program is free software: you can redistribute it and/or
141
modify it under the terms of the GNU General Public License as
142
published by the Free Software Foundation, either version 3 of the
143
License, or (at your option) any later version.
145
This program is distributed in the hope that it will be useful, but
146
WITHOUT ANY WARRANTY; without even the implied warranty of
147
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
148
General Public License for more details.
150
You should have received a copy of the GNU General Public License
151
along with this program. If not, see
152
<http://www.gnu.org/licenses/>.
added
removed
README
