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Committer: Teddy Hogeborn
Date: 2008-09-04 14:04:09 UTC
Revision ID: teddy@fukt.bsnet.se-20080904140409-anr3hckg8ew7q60e

* plugin-runner.xml (BUGS): Document the non-recursiveness of the
"--config-file" option.

files added:
.bzrignore

COPYING

README

initramfs-tools-hook

initramfs-tools-hook-conf

initramfs-tools-script

legalnotice.xml

mandos-keygen

mandos-keygen.xml

mandos-options.xml

overview.xml

plugins.d/usplash

files removed:
network-protocol.txt

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

mandos-client.xml => plugin-runner.xml

files modified:
Makefile

TODO

clients.conf

mandos

mandos-clients.conf.xml

mandos.conf

mandos.conf.xml

mandos.xml

plugins.d/password-prompt.c

plugins.d/password-prompt.xml

plugins.d/password-request.c

plugins.d/password-request.xml

Show diffs side-by-side

added added

removed removed

mandos.xml

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

<?xml-stylesheet type="text/xsl"

href="http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl"?>

<?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">

<!ENTITY TIMESTAMP "2008-09-04">

<title>&COMMANDNAME;</title>

<productname>&COMMANDNAME;</productname>

<title>Mandos Manual</title>

<productname>Mandos</productname>

<productnumber>&VERSION;</productnumber>

<date>&TIMESTAMP;</date>

<firstname>Björn</firstname>

</authorgroup>

<holder>Teddy Hogeborn & Björn Påhlsson</holder>

<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>

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

</refentryinfo>

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

Sends encrypted passwords to authenticated mandos clients

Gives encrypted passwords to authenticated Mandos clients

</refpurpose>

</refnamediv>

<command>&COMMANDNAME;</command>

<arg choice='opt' rep='repeat'>OPTION</arg>

<group>

<arg choice="plain"><option>--interface

<arg choice="plain"><option>-i

</group>

<sbr/>

<group>

<arg choice="plain"><option>--address

<replaceable>ADDRESS</replaceable></option></arg>

<arg choice="plain"><option>-a

<replaceable>ADDRESS</replaceable></option></arg>

</group>

<sbr/>

<group>

<arg choice="plain"><option>--port

<arg choice="plain"><option>-p

</group>

<sbr/>

<arg><option>--priority

<replaceable>PRIORITY</replaceable></option></arg>

<sbr/>

<arg><option>--servicename

<sbr/>

<arg><option>--configdir

<replaceable>DIRECTORY</replaceable></option></arg>

<sbr/>

<arg><option>--debug</option></arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

</group>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

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

</cmdsynopsis>

<command>&COMMANDNAME;</command>

100

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

101

</cmdsynopsis>

102

</refsynopsisdiv>

103

104

105

<title>DESCRIPTION</title>

106

<para>

<command>&COMMANDNAME;</command> is a server daemon that handels

incomming passwords request for passwords. Mandos use avahi to

announce the service, and through gnutls authenticates

clients. Any authenticated client is then given its encrypted

password.

</para>

<para>

show a help message and exit

</para>

</listitem>

</varlistentry>

100

101

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

102

IF</replaceable></literal></term>

103

104

<para>

105

Bind to interface IF

106

</para>

107

</listitem>

108

</varlistentry>

109

110

111

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

112

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

113

114

<para>

115

Address to listen for requests on

116

</para>

117

</listitem>

118

</varlistentry>

119

120

121

122

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

123

124

<para>

125

Port number to receive requests on

126

</para>

127

</listitem>

128

</varlistentry>

129

130

131

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

132

133

<para>

134

Run self-test on the server

135

</para>

136

</listitem>

137

</varlistentry>

138

139

140

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

141

142

<para>

143

Debug mode

144

</para>

145

</listitem>

146

</varlistentry>

147

148

149

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

150

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

151

152

<para>

153

GnuTLS priority string. See <citerefentry>

154

<refentrytitle>gnutls_priority_init</refentrytitle>

155

156

</para>

157

</listitem>

158

</varlistentry>

159

160

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

162

</literal></term>

163

164

<para>

165

Zeroconf service name

166

</para>

167

</listitem>

168

</varlistentry>

169

170

171

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

172

</literal></term>

173

174

<para>

175

Directory to search for configuration files

176

</para>

177

</listitem>

178

</varlistentry>

179

107

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

108

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

109

client host computers. The Mandos server uses Zeroconf to

110

announce itself on the local network, and uses TLS to

111

communicate securely with and to authenticate the clients. The

112

Mandos server uses IPv6 to allow Mandos clients to use IPv6

113

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

114

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

115

Any authenticated client is then given the stored pre-encrypted

116

password for that specific client.

117

</para>

118

</refsect1>

119

120

121

<title>PURPOSE</title>

122

<para>

123

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

124

rebooting</emphasis> of client host computer with an

125

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

126

linkend="overview"/> for details.

127

</para>

128

</refsect1>

129

130

131

<title>OPTIONS</title>

132

133

134

135

136

137

<para>

138

Show a help message and exit

139

</para>

140

</listitem>

141

</varlistentry>

142

143

144

<term><option>--interface</option>

145

146

147

148

149

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

150

</listitem>

151

</varlistentry>

152

153

154

<term><option>--address

155

<replaceable>ADDRESS</replaceable></option></term>

156

<term><option>-a

157

<replaceable>ADDRESS</replaceable></option></term>

158

159

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

160

</listitem>

161

</varlistentry>

162

163

164

<term><option>--port

165

166

<term><option>-p

167

168

169

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

170

</listitem>

171

</varlistentry>

172

173

174

<term><option>--check</option></term>

175

176

<para>

177

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

178

tests, etc.

179

</para>

180

</listitem>

181

</varlistentry>

182

183

184

<term><option>--debug</option></term>

185

186

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

187

</listitem>

188

</varlistentry>

189

190

191

<term><option>--priority <replaceable>

192

PRIORITY</replaceable></option></term>

193

194

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

195

</listitem>

196

</varlistentry>

197

198

199

<term><option>--servicename

200

201

202

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

203

xpointer="servicename"/>

204

</listitem>

205

</varlistentry>

206

207

208

<term><option>--configdir

209

<replaceable>DIRECTORY</replaceable></option></term>

210

211

<para>

212

Directory to search for configuration files. Default is

213

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

214

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

215

216

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

217

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

218

</para>

219

</listitem>

220

</varlistentry>

221

222

223

<term><option>--version</option></term>

224

225

<para>

226

Prints the program version and exit.

227

</para>

228

</listitem>

229

</varlistentry>

230

</variablelist>

231

</refsect1>

232

233

234

<title>OVERVIEW</title>

235

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

236

<para>

237

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

238

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

239

<acronym>RAM</acronym> disk environment.

240

</para>

241

</refsect1>

242

243

244

<title>NETWORK PROTOCOL</title>

245

<para>

246

The Mandos server announces itself as a Zeroconf service of type

247

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

248

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

249

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

250

protocol version, which currently is

251

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

252

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

253

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

254

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

255

The Mandos client must supply an OpenPGP certificate, and the

256

fingerprint of this certificate is used by the Mandos server to

257

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

258

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

259

authentication or authorization is done by the server.

260

</para>

261

<table>

262

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

263

<row>

264

<entry>Mandos Client</entry>

265

<entry>Direction</entry>

266

<entry>Mandos Server</entry>

267

</row>

268

</thead><tbody>

269

<row>

270

<entry>Connect</entry>

271

272

</row>

273

<row>

274

275

276

</row>

277

<row>

278

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

279

</emphasis></entry>

280

281

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

282

</emphasis></entry>

283

</row>

284

<row>

285

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

286

287

</row>

288

<row>

289

290

291

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

292

</row>

293

<row>

294

295

296

<entry>Close</entry>

297

</row>

298

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

299

</refsect1>

300

301

302

<title>CHECKING</title>

303

<para>

304

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

305

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

306

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

307

longer eligible to receive the encrypted password. The timeout,

308

checker program, and interval between checks can be configured

309

both globally and per client; see <citerefentry>

310

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

311

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

312

</para>

313

</refsect1>

314

315

316

<title>LOGGING</title>

317

<para>

318

The server will send log message with various severity levels to

319

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

320

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

321

and also show them on the console.

322

</para>

323

</refsect1>

324

325

326

<title>EXIT STATUS</title>

327

<para>

328

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

329

critical error is encountered.

330

</para>

331

</refsect1>

332

333

334

<title>ENVIRONMENT</title>

335

336

337

338

339

<para>

340

To start the configured checker (see <xref

341

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

342

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

343

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

344

an absolute path is not given. See <citerefentry>

345

346

</citerefentry>.

347

</para>

348

</listitem>

349

</varlistentry>

350

</variablelist>

351

</refsect1>

352

353

354

<title>FILES</title>

355

<para>

356

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

357

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

358

files. The default file names are listed here.

359

</para>

360

361

362

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

363

364

<para>

365

Server-global settings. See

366

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

367

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

368

</para>

369

</listitem>

370

</varlistentry>

371

372

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

373

374

<para>

375

List of clients and client-specific settings. See

376

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

377

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

378

</para>

379

</listitem>

380

</varlistentry>

381

382

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

383

384

<para>

385

The file containing the process id of

386

<command>&COMMANDNAME;</command>.

387

</para>

388

</listitem>

389

</varlistentry>

390

391

392

393

<para>

394

The Unix domain socket to where local syslog messages are

395

sent.

396

</para>

397

</listitem>

398

</varlistentry>

399

400

401

402

<para>

403

This is used to start the configured checker command for

404

each client. See <citerefentry>

405

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

406

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

407

</para>

408

</listitem>

409

</varlistentry>

410

</variablelist>

411

</refsect1>

412

413

414

415

<para>

416

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

417

backtrace. This could be considered a feature.

418

</para>

419

<para>

420

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

421

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

422

permanent storage. This has some security implications, see

423

<xref linkend="CLIENTS"/>.

424

</para>

425

<para>

426

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

427

status of clients, other than analyzing its <systemitem

428

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

429

</para>

430

<para>

431

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

432

</para>

433

<para>

434

Debug mode is conflated with running in the foreground.

435

</para>

436

<para>

437

The console log messages does not show a time stamp.

438

</para>

439

<para>

440

This server does not check the expire time of clients’ OpenPGP

441

keys.

442

</para>

443

</refsect1>

444

445

446

<title>EXAMPLE</title>

447

448

<para>

449

Normal invocation needs no options:

450

</para>

451

<para>

452

<userinput>&COMMANDNAME;</userinput>

453

</para>

454

</informalexample>

455

456

<para>

457

Run the server in debug mode, read configuration files from

458

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

459

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

460

any other official Mandos server on this host:

461

</para>

462

<para>

463

464

465

<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>

466

467

</para>

468

</informalexample>

469

470

<para>

471

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

472

only on the link-local address on that interface:

473

</para>

474

<para>

475

476

477

<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>

478

479

</para>

480

</informalexample>

481

</refsect1>

482

483

484

<title>SECURITY</title>

485

486

<title>SERVER</title>

487

<para>

488

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

489

should not in itself present any security risk to the host

490

computer running it. The program does not need any special

491

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

492

</para>

493

</refsect2>

494

495

<title>CLIENTS</title>

496

<para>

497

The server only gives out its stored data to clients which

498

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

499

guaranteed by the fact that the client sends its OpenPGP

500

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

501

genuine. The server computes the fingerprint of the key

502

itself and looks up the fingerprint in its list of

503

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

504

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

505

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

506

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

507

except the user running the server.

508

</para>

509

<para>

510

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

511

client computers will continually be checked and be assumed

512

compromised if they are gone for too long.

513

</para>

514

<para>

515

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

516

by the server which would therefore declare the client

517

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

518

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

519

regard all clients therein as valid, and hence eligible to

520

receive their passwords. Therefore, be careful when

521

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

522

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

523

fake Mandos client with the keys from the non-encrypted

524

initial <acronym>RAM</acronym> image of the client host. What

525

should be done in that case (if restarting the server program

526

really is necessary) is to stop the server program, edit the

527

configuration file to omit any suspect clients, and restart

528

the server program.

529

</para>

530

<para>

531

For more details on client-side security, see

532

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

533

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

534

</para>

535

</refsect2>

536

</refsect1>

537

538

539

540

<para>

541

542

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

543

544

<refentrytitle>mandos.conf</refentrytitle>

545

546

<refentrytitle>password-request</refentrytitle>

547

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

548

549

</citerefentry>

550

</para>

551

552

553

<term>

554

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

555

</term>

556

557

<para>

558

Zeroconf is the network protocol standard used by clients

559

for finding this Mandos server on the local network.

560

</para>

561

</listitem>

562

</varlistentry>

563

564

<term>

565

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

566

</term>

567

568

<para>

569

Avahi is the library this server calls to implement

570

Zeroconf service announcements.

571

</para>

572

</listitem>

573

</varlistentry>

574

575

<term>

576

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

577

>GnuTLS</ulink>

578

</term>

579

580

<para>

581

GnuTLS is the library this server uses to implement TLS for

582

communicating securely with the client, and at the same time

583

confidently get the client’s public OpenPGP key.

584

</para>

585

</listitem>

586

</varlistentry>

587

588

<term>

589

RFC 4291: <citetitle>IP Version 6 Addressing

590

Architecture</citetitle>

591

</term>

592

593

594

595

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

596

Addresses</citetitle></term>

597

598

</varlistentry>

599

600

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

601

Address</citetitle></term>

602

603

</varlistentry>

604

605

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

606

Addresses</citetitle></term>

607

608

<para>

609

The clients use IPv6 link-local addresses, which are

610

immediately usable since a link-local addresses is

611

automatically assigned to a network interfaces when it

612

is brought up.

613

</para>

614

</listitem>

615

</varlistentry>

616

</variablelist>

617

</listitem>

618

</varlistentry>

619

620

<term>

621

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

622

Protocol Version 1.1</citetitle>

623

</term>

624

625

<para>

626

TLS 1.1 is the protocol implemented by GnuTLS.

627

</para>

628

</listitem>

629

</varlistentry>

630

631

<term>

632

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

633

</term>

634

635

<para>

636

The data sent to clients is binary encrypted OpenPGP data.

637

</para>

638

</listitem>

639

</varlistentry>

640

641

<term>

642

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

643

Security</citetitle>

644

</term>

645

646

<para>

647

This is implemented by GnuTLS and used by this server so

648

that OpenPGP keys can be used.

649

</para>

650

</listitem>

651

</varlistentry>

180

652

</variablelist>

181

653

</refsect1>

182

654

</refentry>

655

656

657

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