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
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
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
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
and do all this *before* the Mandos server timeout kicks in and the
73
Mandos server refuses to give out the key to anyone.
72
all *before* the Mandos server timeout kicks in and the Mandos
73
server refuses to give out the key to anyone.
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
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
78
78
itself up completely, since Mandos servers are no longer running.
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.
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.
86
86
Nope, the network stuff is all done over TLS, which provides
129
129
focused, and competent attacks, but against the early morning knock
130
130
on your door and the sudden absence of all the servers in your
131
131
server room. Which it does nicely.
134
In the early designs, the mandos-client(8mandos) program (which
135
retrieves a password from the Mandos server) also prompted for a
136
password on the terminal, in case a Mandos server could not be
137
found. This duality of purpose was seen to be too complex to be a
138
viable way to continue. Instead, the programs are now separated
139
into mandos-client(8mandos) and password-prompt(8mandos), and a
140
plugin-runner(8mandos) exist to run them both in parallel, allowing
141
the first plugin to succeed to provide the password. This opened up
142
for any number of additional plugins to run, all competing to be the
143
first to find a password and provide it to the plugin runner.
145
Three additional plugins are provided:
147
This prompts for a password when using usplash(8).
149
This prompts for a password when using splashy(8).
150
* askpass-fifo(8mandos)
151
To provide compatibility with the "askpass" program from
152
cryptsetup, this plugin listens to the same FIFO as askpass would
155
More plugins could easily be written and added by the system
156
administrator; see the section called "WRITING PLUGINS" in
157
plugin-runner(8mandos) to learn the plugin requirements.
161
Copyright © 2008,2009 Teddy Hogeborn
162
Copyright © 2008,2009 Björn Påhlsson
166
This program is free software: you can redistribute it and/or
167
modify it under the terms of the GNU General Public License as
168
published by the Free Software Foundation, either version 3 of the
169
License, or (at your option) any later version.
171
This program is distributed in the hope that it will be useful, but
172
WITHOUT ANY WARRANTY; without even the implied warranty of
173
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
174
General Public License for more details.
176
You should have received a copy of the GNU General Public License
177
along with this program. If not, see
178
<http://www.gnu.org/licenses/>.
added
removed
README
