Table of Contents for
Practical UNIX and Internet Security, 3rd Edition

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition Practical UNIX and Internet Security, 3rd Edition by Alan Schwartz Published by O'Reilly Media, Inc., 2003
  1. Cover
  2. Practical Unix & Internet Security, 3rd Edition
  3. A Note Regarding Supplemental Files
  4. Preface
  5. Unix “Security”?
  6. Scope of This Book
  7. Which Unix System?
  8. Conventions Used in This Book
  9. Comments and Questions
  10. Acknowledgments
  11. A Note to Would-Be Attackers
  12. I. Computer Security Basics
  13. 1. Introduction: Some Fundamental Questions
  14. What Is Computer Security?
  15. What Is an Operating System?
  16. What Is a Deployment Environment?
  17. Summary
  18. 2. Unix History and Lineage
  19. History of Unix
  20. Security and Unix
  21. Role of This Book
  22. Summary
  23. 3. Policies and Guidelines
  24. Planning Your Security Needs
  25. Risk Assessment
  26. Cost-Benefit Analysis and Best Practices
  27. Policy
  28. Compliance Audits
  29. Outsourcing Options
  30. The Problem with Security Through Obscurity
  31. Summary
  32. II. Security Building Blocks
  33. 4. Users, Passwords, and Authentication
  34. Logging in with Usernames and Passwords
  35. The Care and Feeding of Passwords
  36. How Unix Implements Passwords
  37. Network Account and Authorization Systems
  38. Pluggable Authentication Modules (PAM)
  39. Summary
  40. 5. Users, Groups, and the Superuser
  41. Users and Groups
  42. The Superuser (root)
  43. The su Command: Changing Who You Claim to Be
  44. Restrictions on the Superuser
  45. Summary
  46. 6. Filesystems and Security
  47. Understanding Filesystems
  48. File Attributes and Permissions
  49. chmod: Changing a File’s Permissions
  50. The umask
  51. SUID and SGID
  52. Device Files
  53. Changing a File’s Owner or Group
  54. Summary
  55. 7. Cryptography Basics
  56. Understanding Cryptography
  57. Symmetric Key Algorithms
  58. Public Key Algorithms
  59. Message Digest Functions
  60. Summary
  61. 8. Physical Security for Servers
  62. Planning for the Forgotten Threats
  63. Protecting Computer Hardware
  64. Preventing Theft
  65. Protecting Your Data
  66. Story: A Failed Site Inspection
  67. Summary
  68. 9. Personnel Security
  69. Background Checks
  70. On the Job
  71. Departure
  72. Other People
  73. Summary
  74. III. Network and Internet Security
  75. 10. Modems and Dialup Security
  76. Modems: Theory of Operation
  77. Modems and Security
  78. Modems and Unix
  79. Additional Security for Modems
  80. Summary
  81. 11. TCP/IP Networks
  82. Networking
  83. IP: The Internet Protocol
  84. IP Security
  85. Summary
  86. 12. Securing TCP and UDP Services
  87. Understanding Unix Internet Servers and Services
  88. Controlling Access to Servers
  89. Primary Unix Network Services
  90. Managing Services Securely
  91. Putting It All Together: An Example
  92. Summary
  93. 13. Sun RPC
  94. Remote Procedure Call (RPC)
  95. Secure RPC (AUTH_DES)
  96. Summary
  97. 14. Network-Based Authentication Systems
  98. Sun’s Network Information Service (NIS)
  99. Sun’s NIS+
  100. Kerberos
  101. LDAP
  102. Other Network Authentication Systems
  103. Summary
  104. 15. Network Filesystems
  105. Understanding NFS
  106. Server-Side NFS Security
  107. Client-Side NFS Security
  108. Improving NFS Security
  109. Some Last Comments on NFS
  110. Understanding SMB
  111. Summary
  112. 16. Secure Programming Techniques
  113. One Bug Can Ruin Your Whole Day . . .
  114. Tips on Avoiding Security-Related Bugs
  115. Tips on Writing Network Programs
  116. Tips on Writing SUID/SGID Programs
  117. Using chroot( )
  118. Tips on Using Passwords
  119. Tips on Generating Random Numbers
  120. Summary
  121. IV. Secure Operations
  122. 17. Keeping Up to Date
  123. Software Management Systems
  124. Updating System Software
  125. Summary
  126. 18. Backups
  127. Why Make Backups?
  128. Backing Up System Files
  129. Software for Backups
  130. Summary
  131. 19. Defending Accounts
  132. Dangerous Accounts
  133. Monitoring File Format
  134. Restricting Logins
  135. Managing Dormant Accounts
  136. Protecting the root Account
  137. One-Time Passwords
  138. Administrative Techniques for Conventional Passwords
  139. Intrusion Detection Systems
  140. Summary
  141. 20. Integrity Management
  142. The Need for Integrity
  143. Protecting Integrity
  144. Detecting Changes After the Fact
  145. Integrity-Checking Tools
  146. Summary
  147. 21. Auditing, Logging, and Forensics
  148. Unix Log File Utilities
  149. Process Accounting: The acct/pacct File
  150. Program-Specific Log Files
  151. Designing a Site-Wide Log Policy
  152. Handwritten Logs
  153. Managing Log Files
  154. Unix Forensics
  155. Summary
  156. V. Handling Security Incidents
  157. 22. Discovering a Break-in
  158. Prelude
  159. Discovering an Intruder
  160. Cleaning Up After the Intruder
  161. Case Studies
  162. Summary
  163. 23. Protecting Against Programmed Threats
  164. Programmed Threats: Definitions
  165. Damage
  166. Authors
  167. Entry
  168. Protecting Yourself
  169. Preventing Attacks
  170. Summary
  171. 24. Denial of Service Attacks and Solutions
  172. Types of Attacks
  173. Destructive Attacks
  174. Overload Attacks
  175. Network Denial of Service Attacks
  176. Summary
  177. 25. Computer Crime
  178. Your Legal Options After a Break-in
  179. Criminal Hazards
  180. Criminal Subject Matter
  181. Summary
  182. 26. Who Do You Trust?
  183. Can You Trust Your Computer?
  184. Can You Trust Your Suppliers?
  185. Can You Trust People?
  186. Summary
  187. VI. Appendixes
  188. A. Unix Security Checklist
  189. Preface
  190. Chapter 1: Introduction: Some Fundamental Questions
  191. Chapter 2: Unix History and Lineage
  192. Chapter 3: Policies and Guidelines
  193. Chapter 4: Users, Passwords, and Authentication
  194. Chapter 5: Users, Groups, and the Superuser
  195. Chapter 6: Filesystems and Security
  196. Chapter 7: Cryptography Basics
  197. Chapter 8: Physical Security for Servers
  198. Chapter 9: Personnel Security
  199. Chapter 10: Modems and Dialup Security
  200. Chapter 11: TCP/IP Networks
  201. Chapter 12: Securing TCP and UDP Services
  202. Chapter 13: Sun RPC
  203. Chapter 14: Network-Based Authentication Systems
  204. Chapter 15: Network Filesystems
  205. Chapter 16: Secure Programming Techniques
  206. Chapter 17: Keeping Up to Date
  207. Chapter 18: Backups
  208. Chapter 19: Defending Accounts
  209. Chapter 20: Integrity Management
  210. Chapter 21: Auditing, Logging, and Forensics
  211. Chapter 22: Discovering a Break-In
  212. Chapter 23: Protecting Against Programmed Threats
  213. Chapter 24: Denial of Service Attacks and Solutions
  214. Chapter 25: Computer Crime
  215. Chapter 26: Who Do You Trust?
  216. Appendix A: Unix Security Checklist
  217. Appendix B: Unix Processes
  218. Appendixes C, D, and E: Paper Sources, Electronic Sources, and Organizations
  219. B. Unix Processes
  220. About Processes
  221. Signals
  222. Controlling and Examining Processes
  223. Starting Up Unix and Logging In
  224. C. Paper Sources
  225. Unix Security References
  226. Other Computer References
  227. D. Electronic Resources
  228. Mailing Lists
  229. Web Sites
  230. Usenet Groups
  231. Software Resources
  232. E. Organizations
  233. Professional Organizations
  234. U.S. Government Organizations
  235. Emergency Response Organizations
  236. Index
  237. Index
  238. Index
  239. Index
  240. Index
  241. Index
  242. Index
  243. Index
  244. Index
  245. Index
  246. Index
  247. Index
  248. Index
  249. Index
  250. Index
  251. Index
  252. Index
  253. Index
  254. Index
  255. Index
  256. Index
  257. Index
  258. Index
  259. Index
  260. Index
  261. Index
  262. Index
  263. About the Authors
  264. Colophon
  265. Copyright

Mailing Lists

There are many mailing lists that cover security-related material. We describe a few of the major ones here. However, this is not to imply that only these lists are worthy of mention! There may well be other lists of which we are unaware, and many of the lesser-known lists often have a higher volume of good information.

Note

Never place blind faith in anything you read in a mailing list, especially if the list is unmoderated. There are a number of self-styled experts on the Net who will not hesitate to volunteer their views, whether knowledgeable or not. Usually, their advice is benign, but sometimes it is quite dangerous. There may also be people who are providing bad advice on purpose, as a form of vandalism. And certainly, there are times when the real experts make a mistake or two in what they recommend in an offhand note posted to the Net.

There are some real experts on these lists who are (happily) willing to share their knowledge with the community, and their contributions make the Internet a better place. However, keep in mind that simply because you read it on the Internet does not mean that the information is correct for your system or environment, that it has been carefully thought out, that it matches your site policy, and it most certainly does not mean that it will help your security. Always evaluate carefully the information you receive before acting on it.

Response Teams and Vendors

Many of the incident response teams (listed in Appendix E) have mailing lists for their advisories and alerts. If you can be classified as one of their constituents, you should contact the appropriate team(s) to be placed on their mailing lists.

Many vendors also have mailing lists for updates and advisories concerning their products. These include computer vendors, firewall vendors, and vendors of security software (including some freeware and shareware products). You may wish to contact your vendors to see if they have such lists, and if so, join.

A Big Problem with Mailing Lists

The problem with all these lists is that you can easily overwhelm yourself. If you are on lists from two response teams, four vendors, and on another half dozen general-purpose lists, you may find yourself filtering several hundred messages a day whenever a new general vulnerability is discovered. At the same time, you don’t want to unsubscribe from these lists because you might then miss the timely announcement of a special-case fix for your own systems.

One method that we have seen others use with some success is to split the mailing lists up among a group of administrators. Each person gets one or two lists to monitor, with particularly useful messages then redistributed to the entire group. Be certain to arrange coverage of these lists if someone leaves or goes on vacation, however!

Another approach is to feed these messages into Usenet newsgroups you create locally especially for this purpose. This strategy allows you to read the messages using an advanced newsreader that will allow you to kill message chains or trigger on keywords. It may also help provide an archiving mechanism to allow you to keep several days or weeks (or more) worth of messages.

Finally, most security mailing lists offer the option of subscribing to a daily digest of the list. Digest subscribers usually receive a single message each day that contains all of the day’s messages. Managing these digests can be easier than sorting through each individual message as they arrive. Of course, you may learn about new vulnerabilities several hours later than other system administrators—or attackers.

Major Mailing Lists

These are some of the major mailing lists.

Bugtraq

Bugtraq is a full-disclosure computer security mailing list run by SecurityFocus. This list features detailed discussions of Unix security holes: what they are, how to exploit them, and what to do to fix them. This list is not intended to be about cracking systems or exploiting their vulnerabilities (although that is known to be the intent of some of the subscribers). It is, instead, about defining—that is, recognizing and preventing security holes and risks. To subscribe, sign up at:

http://www.securityfocus.com/

Note that we have seen some incredibly incorrect and downright bad advice posted to this list. Individuals who attempt to point out errors or corrections are often roundly flamed as being “anti-disclosure.” Post to this list with caution if you are the timid sort.

SecurityFocus also runs several other mailing lists that cover areas of security (such as IDS, honeypots, or viruses) or specific flavors of Unix (such as Linux or Sun systems). A particularly interesting list is “incidents,” which report actual attacks and break-ins. SecurityFocus is owned by the Symantec Corporation

CERT-advisory

New CERT/CC advisories of security flaws and fixes for Internet systems are posted to this list. This list makes somewhat boring reading; often the advisories are so watered down that you cannot easily figure out what is actually being described. Nevertheless, the list does have its bright spots. Send subscription requests to . Put “subscribe cert-advisory” in the message body.

Archived past advisories are available at:

http://www.cert.org/nav/alerts.html.

Computer underground digest

A curious mixture of postings on privacy, security, law, and the computer underground fill this list. Despite the name, this list was not a digest of material by the “underground”—it contained information about the computing milieux. Unfortunately, it stopped publishing in 2000, and it is unclear if the list will ever resume.

This list was available as the newsgroup comp.society.cu-digest on the Usenet; the newsgroup was the preferred means of distribution. The list is archived at numerous places around the Internet, including its home page:

http://sun.soci.niu.edu/~cudigest/

Firewalls

The Firewalls mailing list, which is hosted by the Internet Software Consortium, is a primary forum for folks on the Internet who want to discuss the design, construction, operation, maintenance, and philosophy of Internet firewall security systems. To subscribe, visit:

http://www.isc.org/services/public/lists/firewalls.html

The Firewalls mailing list is usually high-volume (sometimes more than 100 messages per day, although usually it is only several dozen per day). To accommodate subscribers who don’t want their mailboxes flooded with lots of separate messages from Firewalls, a digested version of the list is also available, and the list is archived on the web site.

Firewall-Wizards

The Firewall-Wizards mailing list is a moderated list focused not only on the design and implementation of firewalls but also other network security topics. You can subscribe (or browse the archives) at:

http://honor.icsalabs.com/mailman/listinfo/firewall-wizards

RISKS

RISKS is officially known as the ACM Forum on Risks to the Public in the Use of Computers and Related Systems. It’s a moderated forum for discussing risks to society from computers and computerization. RISKS is also distributed as the comp.risks Usenet newsgroup, and this is the preferred method of subscription. If you don’t get Usenet (and don’t want to read it via http://groups.google.com), you can send email subscription requests to with the word “subscribe” in the body.

Back issues are available through Google (as above) or from:

http://www.risks.org/.

SANS Security Alert Consensus

Security Alert Consensus is a weekly digest of alerts and announcements from several other security mailing lists and vendors. Subscriptions can be customized to include only those operating systems for which you are responsible. Subscribe at:

http://www.sans.org/.