Table of Contents for
Linux Network Administrator's Guide, Second Edition

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition Linux Network Administrator's Guide, Second Edition by Terry Dawson Published by O'Reilly Media, Inc., 2000
  1. Cover
  2. Linux Network Administrator’s Guide, 2nd Edition
  3. Preface
  4. Sources of Information
  5. File System Standards
  6. Standard Linux Base
  7. About This Book
  8. The Official Printed Version
  9. Overview
  10. Conventions Used in This Book
  11. Submitting Changes
  12. Acknowledgments
  13. 1. Introduction to Networking
  14. TCP/IP Networks
  15. UUCP Networks
  16. Linux Networking
  17. Maintaining Your System
  18. 2. Issues of TCP/IP Networking
  19. IP Addresses
  20. Address Resolution
  21. IP Routing
  22. The Internet Control Message Protocol
  23. Resolving Host Names
  24. 3. Configuring the Networking Hardware
  25. A Tour of Linux Network Devices
  26. Ethernet Installation
  27. The PLIP Driver
  28. The PPP and SLIP Drivers
  29. Other Network Types
  30. 4. Configuring the Serial Hardware
  31. Introduction to Serial Devices
  32. Accessing Serial Devices
  33. Serial Hardware
  34. Using the Configuration Utilities
  35. Serial Devices and the login: Prompt
  36. 5. Configuring TCP/IP Networking
  37. Installing the Binaries
  38. Setting the Hostname
  39. Assigning IP Addresses
  40. Creating Subnets
  41. Writing hosts and networks Files
  42. Interface Configuration for IP
  43. All About ifconfig
  44. The netstat Command
  45. Checking the ARP Tables
  46. 6. Name Service and Resolver Configuration
  47. How DNS Works
  48. Running named
  49. 7. Serial Line IP
  50. SLIP Operation
  51. Dealing with Private IP Networks
  52. Using dip
  53. Running in Server Mode
  54. 8. The Point-to-Point Protocol
  55. Running pppd
  56. Using Options Files
  57. Using chat to Automate Dialing
  58. IP Configuration Options
  59. Link Control Options
  60. General Security Considerations
  61. Authentication with PPP
  62. Debugging Your PPP Setup
  63. More Advanced PPP Configurations
  64. 9. TCP/IP Firewall
  65. What Is a Firewall?
  66. What Is IP Filtering?
  67. Setting Up Linux for Firewalling
  68. Three Ways We Can Do Filtering
  69. Original IP Firewall (2.0 Kernels)
  70. IP Firewall Chains (2.2 Kernels)
  71. Netfilter and IP Tables (2.4 Kernels)
  72. TOS Bit Manipulation
  73. Testing a Firewall Configuration
  74. A Sample Firewall Configuration
  75. 10. IP Accounting
  76. Configuring IP Accounting
  77. Using IP Accounting Results
  78. Resetting the Counters
  79. Flushing the Ruleset
  80. Passive Collection of Accounting Data
  81. 11. IP Masquerade and Network Address Translation
  82. Configuring the Kernel for IP Masquerade
  83. Configuring IP Masquerade
  84. Handling Name Server Lookups
  85. More About Network Address Translation
  86. 12. Important Network Features
  87. The tcpd Access Control Facility
  88. The Services and Protocols Files
  89. Remote Procedure Call
  90. Configuring Remote Login and Execution
  91. 13. The Network Information System
  92. NIS Versus NIS+
  93. The Client Side of NIS
  94. Running an NIS Server
  95. NIS Server Security
  96. Setting Up an NIS Client with GNU libc
  97. Choosing the Right Maps
  98. Using the passwd and group Maps
  99. Using NIS with Shadow Support
  100. 14. The Network File System
  101. Mounting an NFS Volume
  102. The NFS Daemons
  103. The exports File
  104. Kernel-Based NFSv2 Server Support
  105. Kernel-Based NFSv3 Server Support
  106. 15. IPX and the NCP Filesystem
  107. IPX and Linux
  108. Configuring the Kernel for IPX and NCPFS
  109. Configuring IPX Interfaces
  110. Configuring an IPX Router
  111. Mounting a Remote NetWare Volume
  112. Exploring Some of the Other IPX Tools
  113. Printing to a NetWare Print Queue
  114. NetWare Server Emulation
  115. 16. Managing Taylor UUCP
  116. UUCP Configuration Files
  117. Controlling Access to UUCP Features
  118. Setting Up Your System for Dialing In
  119. UUCP Low-Level Protocols
  120. Troubleshooting
  121. Log Files and Debugging
  122. 17. Electronic Mail
  123. How Is Mail Delivered?
  124. Email Addresses
  125. How Does Mail Routing Work?
  126. Configuring elm
  127. 18. Sendmail
  128. Installing sendmail
  129. Overview of Configuration Files
  130. The sendmail.cf and sendmail.mc Files
  131. Generating the sendmail.cf File
  132. Interpreting and Writing Rewrite Rules
  133. Configuring sendmail Options
  134. Some Useful sendmail Configurations
  135. Testing Your Configuration
  136. Running sendmail
  137. Tips and Tricks
  138. 19. Getting Exim Up and Running
  139. If Your Mail Doesn’t Get Through
  140. Compiling Exim
  141. Mail Delivery Modes
  142. Miscellaneous config Options
  143. Message Routing and Delivery
  144. Protecting Against Mail Spam
  145. UUCP Setup
  146. 20. Netnews
  147. What Is Usenet, Anyway?
  148. How Does Usenet Handle News?
  149. 21. C News
  150. Installation
  151. The sys File
  152. The active File
  153. Article Batching
  154. Expiring News
  155. Miscellaneous Files
  156. Control Messages
  157. C News in an NFS Environment
  158. Maintenance Tools and Tasks
  159. 22. NNTP and the nntpd Daemon
  160. Installing the NNTP Server
  161. Restricting NNTP Access
  162. NNTP Authorization
  163. nntpd Interaction with C News
  164. 23. Internet News
  165. Newsreaders and INN
  166. Installing INN
  167. Configuring INN: the Basic Setup
  168. INN Configuration Files
  169. Running INN
  170. Managing INN: The ctlinnd Command
  171. 24. Newsreader Configuration
  172. trn Configuration
  173. nn Configuration
  174. A. Example Network: The Virtual Brewery
  175. B. Useful Cable Configurations
  176. A Serial NULL Modem Cable
  177. C. Linux Network Administrator’s Guide, Second Edition Copyright Information
  178. 1. Applicability and Definitions
  179. 2. Verbatim Copying
  180. 3. Copying in Quantity
  181. 4. Modifications
  182. 5. Combining Documents
  183. 6. Collections of Documents
  184. 7. Aggregation with Independent Works
  185. 8. Translation
  186. 9. Termination
  187. 10. Future Revisions of this License
  188. D. SAGE: The System Administrators Guild
  189. Index
  190. Colophon

Chapter 24. Newsreader Configuration

A newsreader is a program that users invoke to view, store, and create news articles. Several newsreaders have been ported to Linux. We will describe the basic setup for the three most popular newsreaders: tin, trn, and nn.

One of the most effective newsreaders is:

$ find /var/spool/news -name '[0-9]*' -exec cat {} \; | more

This is the way Unix die-hards read their news.

Most newsreaders, however, are much more sophisticated. They usually offer a full-screen interface with separate levels for displaying all groups the user has subscribed to, an overview of all articles in each group, and individual articles. Many web browsers double as newsreaders, but if you want to use a standalone newsreader, this chapter explains how to configure two classic ones: trn and nn.

At the newsgroup level, most newsreaders display a list of articles, showing their subject lines and authors. In big groups, it is difficult for the user to keep track of articles relating to each other, although it is possible to identify responses to earlier articles.

A response usually repeats the original article’s subject, prepending it with Re:. Additionally, the References: header line should include the message ID of the article on which the response is directly following up. Sorting articles by these two criteria generates small clusters (in fact, trees) of articles, which are called threads. One of the tasks of writing a newsreader is devising an efficient scheme of threading, because the time required for this is proportional to the square of the number of articles.

We will not go into how the user interfaces are built here. All newsreaders currently available for Linux have a good help function; please refer to it for more details.

In the following sections, we will deal only with administrative tasks. Most of these relate to the creation of threads databases and accounting.

tin Configuration

The most versatile newsreader with respect to threading is tin. It was written by Iain Lea and is loosely modeled on an older newsreader named tass (written by Rich Skrenta). It does its threading when the user enters the newsgroup, and it is pretty fast unless you’re getting posts via NNTP.

On a 486DX50, it takes roughly 30 seconds to thread 1,000 articles when reading directly from disk. It would take more than 5 minutes over NNTP to reach a loaded news server.[140] You may improve this time by regularly updating your index file by invoking tin with the -u option, so that when you next start tin to read news the threads already exist. Alternatively, you can invoke tin with the -U option to read news. When invoked this way, tin forks a background process to build the index files while you are reading news.

Usually, tin dumps its threading databases in the user’s home directory below .tin/index. This may be costly in terms of resources, however, so you should keep a single copy of them in a central location. This may be achieved by making tin setuid to news, for example. tin will then keep all thread databases below /var/spool/news/.index. For any file access or shell escape, it will reset its effective uid to the real uid of the user who invoked it.[141]

The version of tin included in some Linux distributions is compiled without NNTP support, but most do have it now. When invoked as rtin or with the -r option, tin tries to connect to the NNTP server specified in the file /etc/nntpserver or in the NNTPSERVER environment variable. The nntpserver file simply contains the server’s name on a single line.



[140] Things improve drastically if the NNTP server does the threading itself and lets the client retrieve the threads databases; INN does this, for instance.

[141] This is the reason why you will get ugly error messages when invoking tin as superuser. But you shouldn’t do routine work as root, anyway.