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Committer: Teddy Hogeborn
Date: 2008-08-27 01:18:25 UTC
Revision ID: teddy@fukt.bsnet.se-20080827011825-ka3ni6xvy2ehi1y8

* .bzrignore: New.

* clients.conf ([foo]): Remove Radix-64 checksum.

* mandos (AvahiService.rename, server_state_changed,
          entry_group_state_changed): Make Avahi log messages more
                                      clear that they are about
                                      Zeroconf.
  (fingerprint): Use plain "0" instead of "ctypes.c_uint(0)".

files added:
.bzrignore

COPYING

initramfs-tools-hook

initramfs-tools-hook-conf

initramfs-tools-script

mandos-clients.conf.xml

mandos-keygen

mandos-keygen.xml

mandos-options.xml

mandos.conf.xml

mandos.xml

overview.xml

plugin-runner.xml

plugins.d/password-prompt.xml

plugins.d/password-request.xml

plugins.d/usplash

files removed:
network-protocol.txt

files renamed:
mandos-client.c => plugin-runner.c

files modified:
Makefile

TODO

clients.conf

mandos

mandos.conf

plugins.d/password-prompt.c

plugins.d/password-request.c

Show diffs side-by-side

added added

removed removed

mandos.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"

"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [

<!ENTITY VERSION "1.0">

<!ENTITY COMMANDNAME "mandos">

<title>&COMMANDNAME;</title>

<productname>&COMMANDNAME;</productname>

<productnumber>&VERSION;</productnumber>

<firstname>Björn</firstname>

<surname>Påhlsson</surname>

<email>belorn@fukt.bsnet.se</email>

</address>

</author>

<firstname>Teddy</firstname>

<surname>Hogeborn</surname>

<email>teddy@fukt.bsnet.se</email>

</address>

</author>

</authorgroup>

<holder>Teddy Hogeborn</holder>

<holder>Björn Påhlsson</holder>

</copyright>

<para>

This manual page is free software: you can redistribute it

and/or modify it under the terms of the GNU General Public

License as published by the Free Software Foundation,

either version 3 of the License, or (at your option) any

later version.

</para>

<para>

This manual page is distributed in the hope that it will

be useful, but WITHOUT ANY WARRANTY; without even the

implied warranty of MERCHANTABILITY or FITNESS FOR A

PARTICULAR PURPOSE. See the GNU General Public License

for more details.

</para>

<para>

You should have received a copy of the GNU General Public

License along with this program; If not, see

<ulink url="http://www.gnu.org/licenses/"/>.

</para>

</legalnotice>

</refentryinfo>

<refentrytitle>&COMMANDNAME;</refentrytitle>

</refmeta>

<refname><command>&COMMANDNAME;</command></refname>

Sends encrypted passwords to authenticated Mandos clients

</refpurpose>

</refnamediv>

<command>&COMMANDNAME;</command>

<arg>--interface<arg choice="plain">NAME</arg></arg>

<arg>--address<arg choice="plain">ADDRESS</arg></arg>

<arg>--priority<arg choice="plain">PRIORITY</arg></arg>

<arg>--servicename<arg choice="plain">NAME</arg></arg>

<arg>--configdir<arg choice="plain">DIRECTORY</arg></arg>

<arg>--debug</arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

<arg>-a<arg choice="plain">ADDRESS</arg></arg>

<arg>--priority<arg choice="plain">PRIORITY</arg></arg>

<arg>--servicename<arg choice="plain">NAME</arg></arg>

<arg>--configdir<arg choice="plain">DIRECTORY</arg></arg>

<arg>--debug</arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

</group>

</cmdsynopsis>

100

101

<command>&COMMANDNAME;</command>

102

<arg choice="plain">--version</arg>

103

</cmdsynopsis>

104

105

<command>&COMMANDNAME;</command>

106

<arg choice="plain">--check</arg>

107

</cmdsynopsis>

108

</refsynopsisdiv>

109

110

111

<title>DESCRIPTION</title>

112

<para>

113

<command>&COMMANDNAME;</command> is a server daemon which

114

handles incoming request for passwords for a pre-defined list of

115

client host computers. The Mandos server uses Zeroconf to

116

announce itself on the local network, and uses TLS to

117

communicate securely with and to authenticate the clients. The

118

Mandos server uses IPv6 to allow Mandos clients to use IPv6

119

link-local addresses, since the clients will probably not have

120

any other addresses configured (see <xref linkend="overview"/>).

121

Any authenticated client is then given the stored pre-encrypted

122

password for that specific client.

123

</para>

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125

</refsect1>

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127

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<title>PURPOSE</title>

129

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<para>

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The purpose of this is to enable <emphasis>remote and unattended

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rebooting</emphasis> of client host computer with an

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<emphasis>encrypted root file system</emphasis>. See <xref

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linkend="overview"/> for details.

135

</para>

136

137

</refsect1>

138

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140

<title>OPTIONS</title>

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<para>

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Show a help message and exit

148

</para>

149

</listitem>

150

</varlistentry>

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<term><literal>-i</literal>, <literal>--interface <replaceable

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>NAME</replaceable></literal></term>

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<xi:include href="mandos-options.xml" xpointer="interface"/>

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</listitem>

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</varlistentry>

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<term><literal>-a</literal>, <literal>--address <replaceable>

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ADDRESS</replaceable></literal></term>

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<xi:include href="mandos-options.xml" xpointer="address"/>

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</listitem>

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</varlistentry>

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PORT</replaceable></literal></term>

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<xi:include href="mandos-options.xml" xpointer="port"/>

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</listitem>

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</varlistentry>

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<term><literal>--check</literal></term>

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<para>

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Run the server’s self-tests. This includes any unit

181

tests, etc.

182

</para>

183

</listitem>

184

</varlistentry>

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<term><literal>--debug</literal></term>

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<xi:include href="mandos-options.xml" xpointer="debug"/>

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</listitem>

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</varlistentry>

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<term><literal>--priority <replaceable>

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PRIORITY</replaceable></literal></term>

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<xi:include href="mandos-options.xml" xpointer="priority"/>

198

</listitem>

199

</varlistentry>

200

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<term><literal>--servicename <replaceable>NAME</replaceable>

203

</literal></term>

204

205

<xi:include href="mandos-options.xml"

206

xpointer="servicename"/>

207

</listitem>

208

</varlistentry>

209

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<term><literal>--configdir <replaceable>DIR</replaceable>

212

</literal></term>

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<para>

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Directory to search for configuration files. Default is

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<quote><literal>/etc/mandos</literal></quote>. See

217

<citerefentry><refentrytitle>mandos.conf</refentrytitle>

218

219

<refentrytitle>mandos-clients.conf</refentrytitle>

220

<manvolnum>5</manvolnum></citerefentry>.

221

</para>

222

</listitem>

223

</varlistentry>

224

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<term><literal>--version</literal></term>

227

228

<para>

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Prints the program version and exit.

230

</para>

231

</listitem>

232

</varlistentry>

233

</variablelist>

234

</refsect1>

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<title>OVERVIEW</title>

238

<xi:include href="overview.xml"/>

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<para>

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This program is the server part. It is a normal server program

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and will run in a normal system environment, not in an initial

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RAM disk environment.

243

</para>

244

</refsect1>

245

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<title>NETWORK PROTOCOL</title>

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<para>

249

The Mandos server announces itself as a Zeroconf service of type

250

<quote><literal>_mandos._tcp</literal></quote>. The Mandos

251

client connects to the announced address and port, and sends a

252

line of text where the first whitespace-separated field is the

253

protocol version, which currently is

254

<quote><literal>1</literal></quote>. The client and server then

255

start a TLS protocol handshake with a slight quirk: the Mandos

256

server program acts as a TLS <quote>client</quote> while the

257

connecting Mandos client acts as a TLS <quote>server</quote>.

258

The Mandos client must supply an OpenPGP certificate, and the

259

fingerprint of this certificate is used by the Mandos server to

260

look up (in a list read from <filename>clients.conf</filename>

261

at start time) which binary blob to give the client. No other

262

authentication or authorization is done by the server.

263

</para>

264

<table>

265

<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>

266

<row>

267

<entry>Mandos Client</entry>

268

<entry>Direction</entry>

269

<entry>Mandos Server</entry>

270

</row>

271

</thead><tbody>

272

<row>

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<entry>Connect</entry>

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</row>

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<row>

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</row>

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<row>

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<entry>TLS handshake <emphasis>as TLS <quote>server</quote>

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</emphasis></entry>

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<entry>TLS handshake <emphasis>as TLS <quote>client</quote>

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</emphasis></entry>

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</row>

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<row>

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<entry>OpenPGP public key (part of TLS handshake)</entry>

289

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</row>

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<row>

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<entry>Binary blob (client will assume OpenPGP data)</entry>

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</row>

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<row>

297

298

299

<entry>Close</entry>

300

</row>

301

</tbody></tgroup></table>

302

</refsect1>

303

304

305

<title>CHECKING</title>

306

<para>

307

The server will, by default, continually check that the clients

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are still up. If a client has not been confirmed as being up

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for some time, the client is assumed to be compromised and is no

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longer eligible to receive the encrypted password. The timeout,

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checker program, and interval between checks can be configured

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both globally and per client; see <citerefentry>

313

<refentrytitle>mandos-clients.conf</refentrytitle>

314

<manvolnum>5</manvolnum></citerefentry>.

315

</para>

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</refsect1>

317

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319

<title>LOGGING</title>

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<para>

321

The server will send log message with various severity levels to

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<filename>/dev/log</filename>. With the

323

<option>--debug</option> option, it will log even more messages,

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and also show them on the console.

325

</para>

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</refsect1>

327

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<title>EXIT STATUS</title>

330

<para>

331

The server will exit with a non-zero exit status only when a

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critical error is encountered.

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</para>

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</refsect1>

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<title>ENVIRONMENT</title>

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<para>

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To start the configured checker (see <xref

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linkend="checking"/>), the server uses

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<filename>/bin/sh</filename>, which in turn uses

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<varname>PATH</varname> to search for matching commands if

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an absolute path is not given. See <citerefentry>

348

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</citerefentry>.

350

</para>

351

</listitem>

352

</varlistentry>

353

</variablelist>

354

</refsect1>

355

356

357

<title>FILES</title>

358

<para>

359

Use the <option>--configdir</option> option to change where

360

<command>&COMMANDNAME;</command> looks for its configurations

361

files. The default file names are listed here.

362

</para>

363

364

365

<term><filename>/etc/mandos/mandos.conf</filename></term>

366

367

<para>

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Server-global settings. See

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<citerefentry><refentrytitle>mandos.conf</refentrytitle>

370

<manvolnum>5</manvolnum></citerefentry> for details.

371

</para>

372

</listitem>

373

</varlistentry>

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<term><filename>/etc/mandos/clients.conf</filename></term>

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<para>

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List of clients and client-specific settings. See

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<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>

380

<manvolnum>5</manvolnum></citerefentry> for details.

381

</para>

382

</listitem>

383

</varlistentry>

384

385

<term><filename>/var/run/mandos/mandos.pid</filename></term>

386

387

<para>

388

The file containing the process id of

389

<command>&COMMANDNAME;</command>.

390

</para>

391

</listitem>

392

</varlistentry>

393

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<para>

397

The Unix domain socket to where local syslog messages are

398

sent.

399

</para>

400

</listitem>

401

</varlistentry>

402

403

404

405

<para>

406

This is used to start the configured checker command for

407

each client. See <citerefentry>

408

<refentrytitle>mandos-clients.conf</refentrytitle>

409

<manvolnum>5</manvolnum></citerefentry> for details.

410

</para>

411

</listitem>

412

</varlistentry>

413

</variablelist>

414

</refsect1>

415

416

417

418

<para>

419

This server might, on especially fatal errors, emit a Python

420

backtrace. This could be considered a feature.

421

</para>

422

<para>

423

Currently, if a client is declared <quote>invalid</quote> due to

424

having timed out, the server does not record this fact onto

425

permanent storage. This has some security implications, see

426

<xref linkend="CLIENTS"/>.

427

</para>

428

<para>

429

There is currently no way of querying the server of the current

430

status of clients, other than analyzing its <systemitem

431

class="service">syslog</systemitem> output.

432

</para>

433

<para>

434

There is no fine-grained control over logging and debug output.

435

</para>

436

<para>

437

Debug mode is conflated with running in the foreground.

438

</para>

439

<para>

440

The console log messages does not show a timestamp.

441

</para>

442

</refsect1>

443

444

445

<title>EXAMPLE</title>

446

447

<para>

448

Normal invocation needs no options:

449

</para>

450

<para>

451

<userinput>mandos</userinput>

452

</para>

453

</informalexample>

454

455

<para>

456

Run the server in debug mode, read configuration files from

457

the <filename>~/mandos</filename> directory, and use the

458

Zeroconf service name <quote>Test</quote> to not collide with

459

any other official Mandos server on this host:

460

</para>

461

<para>

462

463

464

<userinput>mandos --debug --configdir ~/mandos --servicename Test</userinput>

465

466

</para>

467

</informalexample>

468

469

<para>

470

Run the server normally, but only listen to one interface and

471

only on the link-local address on that interface:

472

</para>

473

<para>

474

475

476

<userinput>mandos --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>

477

478

</para>

479

</informalexample>

480

</refsect1>

481

482

483

<title>SECURITY</title>

484

485

<title>SERVER</title>

486

<para>

487

Running this <command>&COMMANDNAME;</command> server program

488

should not in itself present any security risk to the host

489

computer running it. The program does not need any special

490

privileges to run, and is designed to run as a non-root user.

491

</para>

492

</refsect2>

493

494

<title>CLIENTS</title>

495

<para>

496

The server only gives out its stored data to clients which

497

does have the OpenPGP key of the stored fingerprint. This is

498

guaranteed by the fact that the client sends its OpenPGP

499

public key in the TLS handshake; this ensures it to be

500

genuine. The server computes the fingerprint of the key

501

itself and looks up the fingerprint in its list of

502

clients. The <filename>clients.conf</filename> file (see

503

<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>

504

<manvolnum>5</manvolnum></citerefentry>)

505

<emphasis>must</emphasis> be made non-readable by anyone

506

except the user running the server.

507

</para>

508

<para>

509

As detailed in <xref linkend="checking"/>, the status of all

510

client computers will continually be checked and be assumed

511

compromised if they are gone for too long.

512

</para>

513

<para>

514

If a client is compromised, its downtime should be duly noted

515

by the server which would therefore declare the client

516

invalid. But if the server was ever restarted, it would

517

re-read its client list from its configuration file and again

518

regard all clients therein as valid, and hence eligible to

519

receive their passwords. Therefore, be careful when

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restarting servers if it is suspected that a client has, in

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fact, been compromised by parties who may now be running a

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fake Mandos client with the keys from the non-encrypted

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initial RAM image of the client host. What should be done in

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that case (if restarting the server program really is

525

necessary) is to stop the server program, edit the

526

configuration file to omit any suspect clients, and restart

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the server program.

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</para>

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<para>

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For more details on client-side security, see

531

<citerefentry><refentrytitle>password-request</refentrytitle>

532

<manvolnum>8mandos</manvolnum></citerefentry>.

533

</para>

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</refsect2>

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</refsect1>

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<para>

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541

<refentrytitle>mandos.conf</refentrytitle>

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<refentrytitle>mandos-clients.conf</refentrytitle>

544

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<refentrytitle>password-request</refentrytitle>

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<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>

547

548

</citerefentry>

549

</para>

550

551

552

<term>

553

<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>

554

</term>

555

556

<para>

557

Zeroconf is the network protocol standard used by clients

558

for finding this Mandos server on the local network.

559

</para>

560

</listitem>

561

</varlistentry>

562

563

<term>

564

<ulink url="http://www.avahi.org/">Avahi</ulink>

565

</term>

566

567

<para>

568

Avahi is the library this server calls to implement

569

Zeroconf service announcements.

570

</para>

571

</listitem>

572

</varlistentry>

573

574

<term>

575

<ulink url="http://www.gnu.org/software/gnutls/"

576

>GnuTLS</ulink>

577

</term>

578

579

<para>

580

GnuTLS is the library this server uses to implement TLS for

581

communicating securely with the client, and at the same time

582

confidently get the client’s public OpenPGP key.

583

</para>

584

</listitem>

585

</varlistentry>

586

587

<term>

588

RFC 4291: <citetitle>IP Version 6 Addressing

589

Architecture</citetitle>

590

</term>

591

592

593

594

<term>Section 2.2: <citetitle>Text Representation of

595

Addresses</citetitle></term>

596

597

</varlistentry>

598

599

<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6

600

Address</citetitle></term>

601

602

</varlistentry>

603

604

<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast

605

Addresses</citetitle></term>

606

607

<para>

608

The clients use IPv6 link-local addresses, which are

609

immediately usable since a link-local addresses is

610

automatically assigned to a network interfaces when it

611

is brought up.

612

</para>

613

</listitem>

614

</varlistentry>

615

</variablelist>

616

</listitem>

617

</varlistentry>

618

619

<term>

620

RFC 4346: <citetitle>The Transport Layer Security (TLS)

621

Protocol Version 1.1</citetitle>

622

</term>

623

624

<para>

625

TLS 1.1 is the protocol implemented by GnuTLS.

626

</para>

627

</listitem>

628

</varlistentry>

629

630

<term>

631

RFC 4880: <citetitle>OpenPGP Message Format</citetitle>

632

</term>

633

634

<para>

635

The data sent to clients is binary encrypted OpenPGP data.

636

</para>

637

</listitem>

638

</varlistentry>

639

640

<term>

641

RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer

642

Security</citetitle>

643

</term>

644

645

<para>

646

This is implemented by GnuTLS and used by this server so

647

that OpenPGP keys can be used.

648

</para>

649

</listitem>

650

</varlistentry>

651

</variablelist>

652

</refsect1>

653

</refentry>

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