1
1
<?xml version="1.0" encoding="UTF-8"?>
2
2
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3
3
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4
<!ENTITY TIMESTAMP "2014-06-22">
4
<!ENTITY TIMESTAMP "2020-09-16">
5
5
<!ENTITY % common SYSTEM "common.ent">
61
69
The computers run a small client program in the initial RAM disk
62
70
environment which will communicate with a server over a network.
63
71
All network communication is encrypted using TLS. The clients
64
are identified by the server using an OpenPGP key; each client
72
are identified by the server using a TLS public key; each client
65
73
has one unique to it. The server sends the clients an encrypted
66
74
password. The encrypted password is decrypted by the clients
67
using the same OpenPGP key, and the password is then used to
75
using a separate OpenPGP key, and the password is then used to
68
76
unlock the root file system, whereupon the computers can
69
77
continue booting normally.
73
81
<refsect1 id="introduction">
74
82
<title>INTRODUCTION</title>
84
<!-- This paragraph is a combination and paraphrase of two
85
quotes from the 1995 movie “The Usual Suspects”. -->
76
86
You know how it is. You’ve heard of it happening. The Man
77
87
comes and takes away your servers, your friends’ servers, the
78
88
servers of everybody in the same hosting facility. The servers
124
134
So, at boot time, the Mandos client will ask for its encrypted
125
data over the network, decrypt it to get the password, use it to
126
decrypt the root file, and continue booting.
135
data over the network, decrypt the data to get the password, use
136
the password to decrypt the root file system, and the client can
137
then continue booting.
129
140
Now, of course the initial RAM disk image is not on the
135
146
long, and will no longer give out the encrypted key. The timing
136
147
here is the only real weak point, and the method, frequency and
137
148
timeout of the server’s checking can be adjusted to any desired
141
152
(The encrypted keys on the Mandos server is on its normal file
193
204
No. The server only gives out the passwords to clients which
194
205
have <emphasis>in the TLS handshake</emphasis> proven that
195
they do indeed hold the OpenPGP private key corresponding to
206
they do indeed hold the private key corresponding to that
211
<refsect2 id="sniff">
212
<title>How about sniffing the network traffic and decrypting it
213
later by physically grabbing the Mandos client and using its
216
We only use <acronym>PFS</acronym> (Perfect Forward Security)
217
key exchange algorithms in TLS, which protects against this.
364
385
plugin requirements.
389
<refsect1 id="systemd">
390
<title>SYSTEMD</title>
392
More advanced startup systems like <citerefentry><refentrytitle
393
>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
394
already have their own plugin-like mechanisms for allowing
395
multiple agents to independently retrieve a password and deliver
396
it to the subsystem requesting a password to unlock the root
397
file system. On these systems, it would make no sense to run
398
<citerefentry><refentrytitle>plugin-runner</refentrytitle
399
><manvolnum>8mandos</manvolnum></citerefentry>, the plugins of
400
which would largely duplicate the work of (and conflict with)
401
the existing systems prompting for passwords.
404
As for <citerefentry><refentrytitle>systemd</refentrytitle
405
><manvolnum>1</manvolnum></citerefentry> in particular, it has
407
url="https://systemd.io/PASSWORD_AGENTS/">Password
408
Agents</ulink> system. Mandos uses this via its
409
<citerefentry><refentrytitle>password-agent</refentrytitle
410
><manvolnum>8mandos</manvolnum></citerefentry> program, which is
411
run instead of <citerefentry><refentrytitle
412
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum
413
></citerefentry> when <citerefentry><refentrytitle
414
>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
415
is used during system startup.
420
<xi:include href="bugs.xml"/>
368
423
<refsect1 id="see_also">
369
424
<title>SEE ALSO</title>
380
435
<manvolnum>8</manvolnum></citerefentry>,
381
436
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
382
437
<manvolnum>8mandos</manvolnum></citerefentry>,
438
<citerefentry><refentrytitle>password-agent</refentrytitle>
439
<manvolnum>8mandos</manvolnum></citerefentry>,
383
440
<citerefentry><refentrytitle>mandos-client</refentrytitle>
384
441
<manvolnum>8mandos</manvolnum></citerefentry>,
385
442
<citerefentry><refentrytitle>password-prompt</refentrytitle>
added
removed
intro.xml
