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

Linux Networking

As it is the result of a concerted effort of programmers around the world, Linux wouldn’t have been possible without the global network. So it’s not surprising that in the early stages of development, several people started to work on providing it with network capabilities. A UUCP implementation was running on Linux almost from the very beginning, and work on TCP/IP-based networking started around autumn 1992, when Ross Biro and others created what has now become known as Net-1.

After Ross quit active development in May 1993, Fred van Kempen began to work on a new implementation, rewriting major parts of the code. This project was known as Net-2. The first public release, Net-2d, was made in the summer of 1993 (as part of the 0.99.10 kernel), and has since been maintained and expanded by several people, most notably Alan Cox.[8] Alan’s original work was known as Net-2Debugged. After heavy debugging and numerous improvements to the code, he changed its name to Net-3 after Linux 1.0 was released. The Net-3 code was further developed for Linux 1.2 and Linux 2.0. The 2.2 and later kernels use the Net-4 version network support, which remains the standard official offering today.

The Net-4 Linux Network code offers a wide variety of device drivers and advanced features. Standard Net-4 protocols include SLIP and PPP (for sending network traffic over serial lines), PLIP (for parallel lines), IPX (for Novell compatible networks, which we’ll discuss in Chapter 15), Appletalk (for Apple networks) and AX.25, NetRom, and Rose (for amateur radio networks). Other standard Net-4 features include IP firewalling, IP accounting (discussed later in Chapter 9 and Chapter 10), and IP Masquerade (discussed later in Chapter 11. IP tunnelling in a couple of different flavors and advanced policy routing are supported. A very large variety of Ethernet devices is supported, in addition to support for some FDDI, Token Ring, Frame Relay, and ISDN, and ATM cards.

Additionally, there are a number of other features that greatly enhance the flexibility of Linux. These features include an implementation of the SMB filesystem, which interoperates with applications like lanmanager and Microsoft Windows, called Samba, written by Andrew Tridgell, and an implementation of the Novell NCP (NetWare Core Protocol).[9]

Different Streaks of Development

There have been, at various times, varying network development efforts active for Linux.

Fred continued development after Net-2Debugged was made the official network implementation. This development led to the Net-2e, which featured a much revised design of the networking layer. Fred was working toward a standardized Device Driver Interface (DDI), but the Net-2e work has ended now.

Yet another implementation of TCP/IP networking came from Matthias Urlichs, who wrote an ISDN driver for Linux and FreeBSD. For this driver, he integrated some of the BSD networking code in the Linux kernel. That project, too is no longer being worked on.

There has been a lot of rapid change in the Linux kernel networking implementation, and change is still the watchword as development continues. Sometimes this means that changes also have to occur in other software, such as the network configuration tools. While this is no longer as large a problem as it once was, you may still find that upgrading your kernel to a later version means that you must upgrade your network configuration tools, too. Fortunately, with the large number of Linux distributions available today, this is a quite simple task.

The Net-4 network implementation is now quite mature and is in use at a very large number of sites around the world. Much work has been done on improving the performance of the Net-4 implementation, and it now competes with the best implementations available for the same hardware platforms. Linux is proliferating in the Internet Service Provider environment, and is often used to build cheap and reliable World Wide Web servers, mail servers, and news servers for these sorts of organizations. There is now sufficient development interest in Linux that it is managing to keep abreast of networking technology as it changes, and current releases of the Linux kernel offer the next generation of the IP protocol, IPv6, as a standard offering.

Where to Get the Code

It seems odd now to remember that in the early days of the Linux network code development, the standard kernel required a huge patch kit to add the networking support to it. Today, network development occurs as part of the mainstream Linux kernel development process. The latest stable Linux kernels can be found on ftp://ftp.kernel.org in /pub/linux/kernel/v2.x/, where x is an even number. The latest experimental Linux kernels can be found on ftp://ftp.kernel.org in /pub/linux/kernel/v2.y/, where y is an odd number. There are Linux kernel source mirrors all over the world. It is now hard to imagine Linux without standard network support.


[8] Alan can be reached at

[9] NCP is the protocol on which Novell file and print services are based.