O CTOBER 2005 VOLUME 30 NUMBER 5 THE USENIX MAGAZINE OPINION Musings RIK FARROW OSES FreeBSD 5 SMPng MICHAEL W. LUCAS Better Tools for Kernel Evolution, Please! MARC E. FIUCZYNSKI Solaris 10 Containers PETER BAER GALVIN SYSADMIN DNS-based Spam Rejection HOBBIT Finding Trojans for Fun and Profit BORIS LOZA ISPadmin: Embedded Hardware ROBERT HASKINS SECURITY Security Through Obscurity: A Review of a Few |of FreeBSD’s Lesser-Known Security Capabilities DAVI D MALONE Surviving DDoS Attacks SRI KANTH KANDULA NETWORKING Distributed, Adaptive Resource Allocation for Sensor Networks GEOFFREY MAINLAND AND MATT WELSH BOOK REVIEWS Book Reviews ELIZABETH ZWICKY AND ADAM TUROFF USENIX NOTES The USENIX Association Financial Report for 2004 ...and much more CONFERENCES Linux Kernel Developers Summit; International Workshop on Wireless Traffic Measurements and Modeling (WitMeMo ’05);Workshop on End-to-End, Sense and Respond Systems, Applications, and Services (EESR ’05); MobiSys 2005:The Third International Conference on Mobile Systems, Applications, and Services; HotOS X:Tenth Workshop on Hot Topics in Operating Systems;VEE ’05: First International Conference on Virtual Execution Environments; Steps to Reducing Unwanted Traffic on the Internet Workshop (SRUTI ’05) The Advanced Computing Systems Association Upcoming Events ACM/IFIP/USENIX 6TH INTERNATIONAL 3RD SYMPOSIUM ON NETWORKED SYSTEMS MIDDLEWARE CONFERENCE DESIGN AND IMPLEMENTATION (NSDI ’06) NOVEMBER 28–DECEMBER 2, 2005, GRENOBLE, FRANCE Sponsored by USENIX, in cooperation with ACM SIGCOMM http://middleware05.objectweb.org and ACM SIGOPS MAY 8–10, 2006, SAN JOSE, CA, USA http://www.usenix.org/nsdi06 19TH LARGE INSTALLATION SYSTEM Paper titles and abstracts due: October 10, 2005 ADMINISTRATION CONFERENCE (LISA ’05) Final paper submissions due: October 17, 2005 Sponsored by USENIX and SAGE DECEMBER 4–9, 2005, SAN DIEGO, CA, USA 5TH SYSTEM ADMINISTRATION AND NETWORK http://www.usenix.org/lisa05 ENGINEERING CONFERENCE (SANE 2006) Organized by Stichting SANE and co-sponsored by Stichting NLnet, USENIX, and SURFnet 2ND WORKSHOP ON REAL, LARGE MAY 15–19, 2006, DELFT, THE NETHERLANDS DISTRIBUTED SYSTEMS (WORLDS ’05) http://www.sane.nl/sane2006 DECEMBER 13, 2005, SAN FRANCISCO, CA, USA Paper submissions due: October 24, 2005 http://www.usenix.org/worlds05 2006 USENIX ANNUAL TECHNICAL 3RD INTERNATIONAL IEEE SECURITY IN STORAGE CONFERENCE (USENIX ’06) WORKSHOP MAY 30–JUNE 3, BOSTON, MA, USA Sponsored by IEEE Computer Society Task Force on Information http://www.usenix.org/usenix06 Assurance (TFIA) in cooperation with IEEE Mass Storage Systems Paper submissions due: January 17, 2006 Technical Committee (MSSTC) and USENIX DECEMBER 13, 2005, SAN FRANCISCO, CA, USA http://www.ieeeia.org/sisw/2005 15TH USENIX SECURITY SYMPOSIUM (SECURITY ’06) JULY 31–AUGUST 4, VANCOUVER, B.C., CANADA 4TH USENIX CONFERENCE ON FILE AND http://www.usenix.org/sec06 STORAGE TECHNOLOGIES (FAST ’05) Paper submissions due: February 1, 2006 Sponsored by USENIX in cooperation with ACM SIGOPS, IEEE Mass Storage Systems Technical Committee (MSSTC), and IEEE TCOS 7TH SYMPOSIUM ON OPERATING SYSTEMS DECEMBER 13–16, 2005, SAN FRANCISCO, CA, USA DESIGN AND IMPLEMENTATION (OSDI ’06) http://www.usenix.org/fast05 NOVEMBER 6–8, SEATTLE, WA, USA http://www.usenix.org/osdi06 Paper submissions due: April 24, 2006 7TH IEEE WORKSHOP ON MOBILE COMPUTING SYSTEMS AND APPLICATIONS (WMCSA 2006) Sponsored by IEEE Computer Society in cooperation with USENIX APRIL 6–7, 2006, SEMIAHMOO RESORT, WA, USA http://research.ihost.com/wmcsa2006/ Paper submissions due: October 1, 2005 For a complete list of all USENIX & USENIX co-sponsored events, see http://www.usenix.org/events OPINION 2 Musings RIK FARROW OPERATING SYSTEMS 4 FreeBSD 5 SMPng MICHAEL W. LUCAS 8 Better Tools for Kernel Evolution, Please! MARC E. FIUCZYNSKI 11 Solaris 10 Containers contents PETER BAER GALVIN SYSADMIN 15 DNS-based Spam Rejection HOBBIT 19 Finding Trojans for Fun and Profit BORIS LOZA 23 ISPadmin: Embedded Hardware ROBERT HASKINS SECURITY 27 Security Through Obscurity: A Review of a Few of FreeBSD’s Lesser-Known Security Capabilities DAVID MALONE 35 Surviving DDoS Attacks SRIKANTH KANDULA NETWORKING 40 Distributed, Adaptive Resource Allocation for Sensor Networks VOL. 30, NO. 5, OCTOBER 2005 GEOFFREY MAINLAND AND MATT WELSH EDITOR ;login: is the official BOOK REVIEWS Rik Farrow magazine of the [email protected] USENIX Association. 45 Book Reviews ELIZABETH ZWICKY AND ADAM TUROFF MANAGING EDITOR ;login: (ISSN 1044-6397) is Jane-Ellen Long published bi-monthly by the USENIX NOTES [email protected] USENIX Association, 2560 COPY EDITOR Ninth Street, Suite 215, 48 25 Years Ago Steve Gilmartin Berkeley, CA 94710. PETER H. SALUS [email protected] $85 of each member’s annual 49 SAGE Update dues is for an annual sub- PRODUCTION CHRIS PALMER Rob Carroll scription to ;login:. Subscrip- Casey Henderson tions for nonmembers are 49 USACO, the USA Computing Olympiad $115 per year. TYPESETTER ROB KOLSTAD Star Type Periodicals postage paid at 50 The USENIX Association Financial Report for [email protected] Berkeley, CA, and additional offices. 2004 USENIX ASSOCIATION 2560 Ninth Street, POSTMASTER: Send address CONFERENCE REPORTS Suite 215, Berkeley, changes to ;login:, California 94710 USENIX Association, 55 Linux Kernel Developers Summit Phone: (510) 528-8649 2560 Ninth Street, JONATHAN CORBET FAX: (510) 548-5738 Suite 215, Berkeley, CA 94710. 57 International Workshop on Wireless Traffic http://www.usenix.org http://www.sage.org ©2005 USENIX Association. Measurements and Modeling (WitMeMo ’05) USENIX is a registered trade- 60 Workshop on End-to-End, Sense and Respond mark of the USENIX Associa- Systems, Applications, and Services (EESR ’05) tion. Many of the designa- tions used by manufacturers 64 MobiSys 2005:The Third International and sellers to distinguish their Conference on Mobile Systems, Applications, products are claimed as trade- and Services marks. USENIX acknowl- edges all trademarks herein. 75 HotOS X:Tenth Workshop on Hot Topics in Where those designations ap- Operating Systems pear in this publication and USENIX is aware of a trade- 86 VEE ’05: First International Conference on mark claim, the designations Virtual Execution Environments have been printed in caps or initial caps. 92 Steps to Reducing Unwanted Traffic on the Internet Workshop (SRUTI ’05) FOR THE PAST COUPLE OF MONTHS, I have become absorbed in operating sys- RIK FARROW tems. My quest began with some consult- ing regarding security features of the cur- rent Linux kernel, including SELinux, then plunged even deeper during the HotOS workshop. I do not pretend to be a kernel hacker, but I am very interested in what musings goes on with the design and implementa- Rik Farrow provides UNIX and Internet security con- tion of operating system software. sulting and training. He is the author of UNIX System Security and System Administrator’s Guide to System V and editor of the SAGE Short Topics in System Like some others, I had wondered what had hap- Administration series. pened to FreeBSD 4’s stellar performance when Free- [email protected] BSD 5 appeared. Instead of getting faster, FreeBSD was slower. If I had bothered digging deeper, I would have learned that this was the result of far-reaching changes in the FreeBSD kernel. Michael W. Lucas ex- plains these changes in his article, which in turn is based on a talk given by Robert Watson about modify- ing the kernel to support SMP (symmetric multipro- cessing). And perhaps by the time you read this col- umn, FreeBSD 6 will have appeared, ready to utilize the new multiprocessor cores that are popping up. Lucas explains just why the transition from single- threaded to multi-threaded kernel takes so long and is so hard to do right. I first understood the importance of the Big Giant Lock when I was reviewing an early multiprocessing server that used SPARC processors. I ran a simple benchmark that spawned additional processes, each of which ran an integer-intensive pro- gram. I tried my benchmark with one processor, then two, three, and, finally, four processors enabled, and the results astounded me (at the time). Adding pro- cessors does not in itself linearly improve perfor- mance. Enabling the fourth processor barely added a 15% improvement to the results. The Big Giant Lock ensures that only one process (or interrupt handler) can run in kernel space at a time, which devastates performance. The HotOS workshop (see the summaries in this issue) brought different surprises. I enjoyed the work- shop immensely, as much for the free time spent with attendees as for the talks. The lunchtime discussions have sparked one article already, in which Marc Fiuc- zynski makes a fervent plea for better methods for patching Linux kernels. You will also find a discussion of the Linux Kernel Developers Summit by Jonathan Corbet. Corbet, who has been summarizing the summits for years, has pro- vided a short overview for ;login: readers. And Peter Galvin explains Solaris 10 containers. Note that Sun bit the SMP revision bullet years ago, making it a 2 ;LO GIN: V OL. 30, NO. 5 leader in SMP OSes today. The concept of containers adds a powerful twist to Solaris, a useful VM architecture unlike others you may know about. On the security front, David Malone discusses security features of FreeBSD. As I read this, I found myself wishing that some of these appeared in Linux as well. But BSD-envy is nothing new. Srikanth Kandula explains Kill-Bots, based on a paper he presented at NSDI (see the summaries in the August issue of ;login:). You might note that instead of my usual musings, I have acted much more like an editor this time around. I apologize, but this issue is so packed with sum- maries and articles, I really didn’t have the space for me. You can expect that my column will appear much as it has in the past in the December issue of ;login:, with its focus on security.