President of F R E E BSD: NOT JUST FOR ALPHA GEEKS the FreeBSD Foundation ANYMORE! With a foreword by ROBERT WATSON, • Use advanced security features like packet filtering, virtual machines, and host-based intrusion detection • Build custom live FreeBSD CDs and bootable flash • Manage network services and filesystems • Use DNS and set up email, IMAP, web, and FTP services for both servers and clients • Monitor your system with performance-testing and troubleshooting tools • Run diskless systems “ I L AY F L AT ” This book uses RepKover — a durable binding that won’t snap shut Printed on recycled paper • Integrate FreeBSD-specific SNMP into your network management system Whether you’re just getting started with FreeBSD or you’ve been using it for years, you’ll find this book to be the definitive guide to FreeBSD that you’ve been waiting for ABOUT THE AUTHOR Michael W Lucas is a network engineer and system administrator responsible for a network that stretches across the Western Hemisphere He is the author of the critically acclaimed Absolute OpenBSD, Cisco Routers for the Desperate, and PGP & GPG, all from No Starch Press Despite being from Detroit, Michigan, he knows almost nothing about automobiles He has been using Unix systems for over 20 years and FreeBSD since 1995 Fortunately for the rest of us, his writing keeps him too busy to implement his plans for world domination COMPLETE GUIDE TO FREEBSD MICH A EL W LUC A S $59.95 ($65.95 CDN) SHELVE IN: OPERATING SYSTEMS/UNIX w w w.nostarch.com • Implement redundant disks, without special hardware T H E LUCAS T H E F I N E ST I N G E E K E N T E RTA I N M E N T ™ • Build custom network appliances with embedded FreeBSD F R2 NED E B S D EDITION 2N ND D EE D D II TT II O ON N Absolute FreeBSD, 2nd Edition is your complete guide to FreeBSD, written by FreeBSD committer Michael W Lucas Lucas considers this completely revised and rewritten second edition of his landmark work to be his best work ever; a true product of his love for FreeBSD and the support of the FreeBSD community Absolute FreeBSD, 2nd Edition covers installation, networking, security, network services, system performance, kernel tweaking, filesystems, SMP, upgrading, crash debugging, and much more, including coverage of how to: • Manage schedulers, remap shared libraries, and optimize your system for your hardware and your workload ABSOLUTE FREEBSD FreeBSD—the powerful, flexible, and free Unix-like operating system—is the preferred server for many enterprises But it can be even trickier to use than either Unix or Linux, and harder still to master ABSOLUTE www.it-ebooks.info ® www.it-ebooks.info PRAISE FOR THE FIRST EDITION, ABSOLUTE BSD “Even longtime users of FreeBSD may be surprised at the power and features it can bring to bear as a server platform, and Absolute BSD is an excellent guide to harnessing that power.” —UNIXREVIEW.COM “ provides beautifully written tutorials and reference material to help you make the most of the strengths of this OS.” —LINUXUSER & DEVELOPER MAGAZINE “ a great resource for people new to BSD and those who have been using it for years Michael Lucas has a writing style which is very easy to read and absorb.” —FRESHMEAT “A very fine piece of work, it isn’t about how to implement BSD solutions, but it is about managing systems in situ.” –;LOGIN: “ packed with a lot of information.” —DAEMON NEWS PRAISE FOR ABSOLUTE OPENBSD BY MICHAEL LUCAS “Absolute OpenBSD by Michael Lucas is a broad and mostly gentle introduction into the world of the OpenBSD operating system It is sufficiently complete and deep to give someone new to OpenBSD a solid footing for doing real work and the mental tools for further exploration The potentially boring topic of systems administration is made very readable and even fun by the light tone that Lucas uses.” —CHRIS PALMER, PRESIDENT, SAN FRANCISCO O PENBSD USERS GROUP “ a well-written book that hits its market squarely on target Those new to OpenBSD will appreciate the comprehensive approach that takes them from concept to functional execution Existing and advanced users will benefit from the discussion of OpenBSD-specific topics such as the security features and pf administration.” —SLASHDOT “I recommend Absolute OpenBSD to all programmers and administrators working with the OpenBSD operating system (OS), or considering it.” —UNIXREVIEW.COM www.it-ebooks.info PRAISE FOR PGP & GPG BY MICHAEL LUCAS “PGP & GPG is another excellent book by Michael Lucas I thoroughly enjoyed his other books due to their content and style PGP & GPG continues in this fine tradition If you are trying to learn how to use PGP or GPG, or at least want to ensure you are using them properly, read PGP & GPG.” —TAOSECURITY “The world’s first user-friendly book on email privacy Unless you’re a cryptographer, or never use email, you should read this book.” —LEN SASSAMAN, CODECON FOUNDER “ Excellent tutorial, quick read, and enough humor to make it enjoyable.” —INFOWORLD “An excellent book that shows the end-user in an easy to read and often entertaining style just about everything they need to know to effectively and properly use PGP and OpenPGP.” —SLASHDOT PRAISE FOR CISCO ROUTERS FOR THE DESPERATE BY MICHAEL LUCAS “ this book isn’t a reference—it’s a survival guide, a ‘break glass in case of emergency’ safety harness What I found remarkable was how it was obviously written for people like me—those of us who have little interest in router management but whose jobs depend on the consistent, trusted functioning of such infrastructure —ASP.NETPRO “If only Cisco Routers for the Desperate had been on my bookshelf a few years ago! It would have definitely saved me many hours of searching for configuration help on my Cisco routers I would strongly recommend this book for both IT Professionals looking to get started with Cisco routers, as well as anyone who has to deal with a Cisco router from time to time but doesn’t have the time or technological know-how to tackle a more in-depth book on the subject.” —BLOGCRITICS MAGAZINE www.it-ebooks.info ABSOLUTE FREEBSD 2ND EDITION THE COMPLETE GUIDE TO FREEBSD by Mi chael W L u cas ® San Francisco www.it-ebooks.info ABSOLUTE FREEBSD, 2ND EDITION Copyright © 2008 by Michael W Lucas All rights reserved No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher Printed on recycled paper in the United States of America 11 10 09 08 07 123456789 ISBN-10: 1-59327-151-4 ISBN-13: 978-1-59327-151-0 Publisher: William Pollock Production Editors: Christina Samuell and Megan Dunchak Cover and Interior Design: Octopod Studios Developmental Editor: William Pollock Technical Reviewer: John Baldwin Copyeditor: Dmitry Kirsanov Compositor: Riley Hoffman Proofreader: Alina Kirsanova Indexer: Nancy Guenther For information on book distributors or translations, please contact No Starch Press, Inc directly: No Starch Press, Inc 555 De Haro Street, Suite 250, San Francisco, CA 94107 phone: 415.863.9900; fax: 415.863.9950; info@nostarch.com; www.nostarch.com Librar y of Congress Cataloging-in-Publication Data Lucas, Michael, 1967Absolute FreeBSD : the complete guide to FreeBSD / Michael W Lucas 2nd ed p cm Includes index ISBN-13: 978-1-59327-145-9 ISBN-10: 1-59327-145-X FreeBSD UNIX (Computer file) Internet service providers Computer programs servers Computer programs Client/server computing I Title QA76.76.O63L83 2007 004'.36 dc22 2007036190 Web No Starch Press and the No Starch Press logo are registered trademarks of No Starch Press, Inc Other product and company names mentioned herein may be the trademarks of their respective owners Rather than use a trademark symbol with every occurrence of a trademarked name, we are using the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark The mark “FreeBSD” is a registered trademark of The FreeBSD Foundation and is used by Michael W Lucas with the permission of The FreeBSD Foundation The FreeBSD Logo is a trademark of The FreeBSD Foundation and is used by Michael W Lucas with the permission of The FreeBSD Foundation The BSD Daemon is copyright Marshall Kirk McKusick and is used with permission The information in this book is distributed on an “As Is” basis, without warranty While every precaution has been taken in the preparation of this work, neither the author nor No Starch Press, Inc shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in it www.it-ebooks.info For Liz With luck, this one is the right size to plug that dang gopher hole www.it-ebooks.info www.it-ebooks.info BRIEF CONTENTS Foreword by Robert N.M Watson xxvii Acknowledgments xxix Introduction Chapter 1: Getting More Help 19 Chapter 2: Installing FreeBSD 33 Chapter 3: Start Me Up! The Boot Process 61 Chapter 4: Read This Before You Break Something Else! (Backup and Recovery) 89 Chapter 5: Kernel Games 117 Chapter 6: The Network 145 Chapter 7: Securing Your System 177 Chapter 8: Disks and Filesystems 209 Chapter 9: Advanced Security Features 261 Chapter 10: Exploring /etc 301 Chapter 11: Making Your System Useful 315 Chapter 12: Advanced Software Management .343 Chapter 13: Upgrading FreeBSD 371 www.it-ebooks.info Chapter 14: The Internet Road Map: DNS .411 Chapter 15: Small System Services .439 Chapter 16: Spam, Worms, and Viruses (Plus Email, If You Insist) .467 Chapter 17: Web and FTP Services .499 Chapter 18: Disk Tricks with GEOM 529 Chapter 19: System Performance and Monitoring 569 Chapter 20: The Fringe of FreeBSD .603 Chapter 21: System (and Sysadmin) Panics and Crashes 637 Afterword 655 Appendix: Some Interesting sysctl MIBs 661 Index 675 viii B ri ef C on ten t s www.it-ebooks.info ... MAGAZINE www.it-ebooks.info ABSOLUTE FREEBSD 2ND EDITION THE COMPLETE GUIDE TO FREEBSD by Mi chael W L u cas ® San Francisco www.it-ebooks.info ABSOLUTE FREEBSD, 2ND EDITION Copyright © 2008 by...www.it-ebooks.info PRAISE FOR THE FIRST EDITION, ABSOLUTE BSD “Even longtime users of FreeBSD may be surprised at the power and features it can bring to bear as a server platform, and Absolute BSD is an excellent... situ.” –;LOGIN: “ packed with a lot of information.” —DAEMON NEWS PRAISE FOR ABSOLUTE OPENBSD BY MICHAEL LUCAS Absolute OpenBSD by Michael Lucas is a broad and mostly gentle introduction into