1. Chapter 1 Introduction to SSH

   1. What Is SSH?

   2. What SSH Is Not

   3. The SSH Protocol

   4. Overview of SSH Features

   5. History of SSH

   6. Related Technologies

   7. Summary

2. Chapter 2 Basic Client Use

   1. A Running Example

   2. Remote Terminal Sessions with ssh

   3. Adding Complexity to the Example

   4. Authentication by Cryptographic Key

   5. The SSH Agent

   6. Connecting Without a Password or Passphrase

   7. Miscellaneous Clients

   8. Summary

3. Chapter 3 Inside SSH

   1. Overview of Features

   2. A Cryptography Primer

   3. The Architecture of an SSH System

   4. Inside SSH-2

   5. Inside SSH-1

   6. Implementation Issues

   7. SSH and File Transfers (scp and sftp)

   8. Algorithms Used by SSH

   9. Threats SSH Can Counter

   10. Threats SSH Doesn't Prevent

   11. Threats Caused by SSH

   12. Summary

4. Chapter 4 Installation and Compile-Time Configuration

   1. Overview

   2. Installing OpenSSH

   3. Installing Tectia

   4. Software Inventory

   5. Replacing r-Commands with SSH

   6. Summary

5. Chapter 5 Serverwide Configuration

   1. Running the Server

   2. Server Configuration: An Overview

   3. Getting Ready: Initial Setup

   4. Authentication: Verifying Identities

   5. Access Control: Letting People In

   6. User Logins and Accounts

   7. Forwarding

   8. Subsystems

   9. Logging and Debugging

   10. Compatibility Between SSH-1 and SSH-2 Servers

   11. Summary

6. Chapter 6 Key Management and Agents

   1. What Is an Identity?

   2. Creating an Identity

   3. SSH Agents

   4. Multiple Identities

   5. PGP Authentication in Tectia

   6. Tectia External Keys

   7. Summary

7. Chapter 7 Advanced Client Use

   1. How to Configure Clients

   2. Precedence

   3. Introduction to Verbose Mode

   4. Client Configuration in Depth

   5. Secure Copy with scp

   6. Secure, Interactive Copy with sftp

   7. Summary

8. Chapter 8 Per-Account Server Configuration

   1. Limits of This Technique

   2. Public-Key-Based Configuration

   3. Hostbased Access Control

   4. The User rc File

   5. Summary

9. Chapter 9 Port Forwarding and X Forwarding

   1. What Is Forwarding?

   2. Port Forwarding

   3. Dynamic Port Forwarding

   4. X Forwarding

   5. Forwarding Security: TCP-Wrappers and libwrap

   6. Summary

10. Chapter 10 A Recommended Setup

    1. The Basics

    2. Compile-Time Configuration

    3. Serverwide Configuration

    4. Per-Account Configuration

    5. Key Management

    6. Client Configuration

    7. Remote Home Directories (NFS, AFS)

    8. Summary

11. Chapter 11 Case Studies

    1. Unattended SSH: Batch or cron Jobs

    2. FTP and SSH

    3. Pine, IMAP, and SSH

    4. Connecting Through a Gateway Host

    5. Scalable Authentication for SSH

    6. Tectia Extensions to Server Configuration Files

    7. Tectia Plugins

12. Chapter 12 Troubleshooting and FAQ

    1. Debug Messages: Your First Line of Defense

    2. Problems and Solutions

    3. Other SSH Resources

13. Chapter 13 Overview of Other Implementations

    1. Common Features

    2. Covered Products

    3. Other SSH Products

14. Chapter 14 OpenSSH for Windows

    1. Installation

    2. Using the SSH Clients

    3. Setting Up the SSH Server

    4. Public-Key Authentication

    5. Troubleshooting

    6. Summary

15. Chapter 15 OpenSSH for Macintosh

    1. Using the SSH Clients

    2. Using the OpenSSH Server

16. Chapter 16 Tectia for Windows

    1. Obtaining and Installing

    2. Basic Client Use

    3. Key Management

    4. Accession Lite

    5. Advanced Client Use

    6. Port Forwarding

    7. Connector

    8. File Transfers

    9. Command-Line Programs

    10. Troubleshooting

    11. Server

17. Chapter 17 SecureCRT and SecureFX for Windows

    1. Obtaining and Installing

    2. Basic Client Use

    3. Key Management

    4. Advanced Client Use

    5. Forwarding

    6. Command-Line Client Programs

    7. File Transfer

    8. Troubleshooting

    9. VShell

    10. Summary

18. Chapter 18 PuTTY for Windows

    1. Obtaining and Installing

    2. Basic Client Use

    3. File Transfer

    4. Key Management

    5. Advanced Client Use

    6. Forwarding

    7. Summary

1. Appendix A OpenSSH 4.0 New Features

   1. Server Features: sshd

   2. Client Features: ssh, scp, and sftp

   3. ssh-keygen

2. Appendix B Tectia Manpage for sshregex

   1. Regex Syntax: Egrep Patterns

   2. Regex Syntax: ZSH_FILEGLOBTectia (continued)sshregex manpageZSH_FILEGLOB sshregex (Tectia) manpageZSH_FILEGLOB regular expressions manpage (Tectia)ZSH_FILEGLOB (or Traditional) Patterns

   3. Character Sets for Egrep and ZSH_FILEGLOB

   4. Regex Syntax: SSH Patterns

   5. Authors

   6. See Also

3. Appendix C Tectia Module Names for Debugging

4. Appendix D SSH-1 Features of OpenSSH and Tectia

   1. OpenSSH Features

   2. Tectia Features

5. Appendix E SSH Quick Reference

   1. Legend

   2. sshd Options

   3. sshd Keywords

   4. ssh Options

   5. scp Options

   6. ssh and scp Keywords

   7. ssh-keygen Options

   8. ssh-agent Options

   9. ssh-add Options

   10. Identity and Authorization Files, OpenSSH

   11. Identity and Authorization Files, Tectia

   12. Environment Variables

6. Colophon

About the Authors Daniel J. Barrett, Ph.D., has been immersed in Internet technology since 1985. Currently working as a software engineer, Dan has also been a heavy metal singer, Unix system administrator, university lecturer, web designer, and humorist. He is the author of O'Reilly's Linux Pocket Guide, and is the coauthor of Linux Security Cookbook and the first edition of SSH, The Secure Shell: The Definitive Guide. He also writes monthly columns for Compute! and Keyboard Magazine, as well as articles for the O'Reilly Network. Richard E. Silverman has a B.A. in computer science and an M.A. in pure mathematics. Richard has worked in the fields of networking, formal methods in software development, public-key infrastructure, routing security, and Unix systems administration. He coauthored the first edition of SSH, The Secure Shell: The Definitive Guide, and he loves to read, study languages and mathematics, sing, dance, and exercise. Robert G. Byrnes, Ph.D., has been hacking on Unix systems for 20 years, and has been involved with security issues since the original Internet worm was launched from Cornell University, while he was a graduate student and system administrator. Currently, he's a software engineer at Curl Corporation. He has worked in the fields of networking, telecommunications, distributed computing, financial technology, and condensed matter physics. Colophon Our look is the result of reader comments, our own experimentation, and feedback from distribution channels. Distinctive covers complement our distinctive approach to technical topics, breathing personality and life into potentially dry subjects. The animal on the cover of SSH, the Secure Shell: The Definitive Guide is a land snail (Mollusca gastropoda). A member of the mollusk family, a snail has a soft, moist body that is protected by a hard shell, into which it can retreat when in danger or when in arid or bright conditions. Snails prefer wet weather and, though not nocturnal, will stay out of bright sun. At the front of a snail's long body are two sets of tentacles: its eyes are at the end of one set, and the other set is used for smelling and navigation. Land snails are hermaphrodites, each having both female and male sex organs, though a snail must mate with another snail in order for fertilization to occur. A snail lays eggs approximately six times a year, with almost 100 eggs each time. Young snails hatch in a month and become adults in two years. A snail's life span is approximately 5-10 years. Known as a slow mover, a snail moves by muscles on its underside that contract and expand, propelling the snail along at a slow pace. It leaves a wet trail of mucus, which protects the snail from anything sharp it may need to crawl over as it searches for food. The snail's diet of plants, bark, and fruits causes it to be a pest in many parts of the world where it is notorious for destroying crops. Mary Brady was the production editor for SSH, the Secure Shell: The Definitive Guide . Audrey Doyle proofread the book. Marlowe Shaeffer and Mary Anne Weeks Mayo provided quality control. Lydia Onofrei provided production assistance. John Bickelhaupt wrote the index. Ellie Volckhausen designed the cover of this book, based on a series design by Edie Freedman. The cover image is an original engraving from the book Natural History of Animals by Sanborn Tenney and Abby A. Tenney, published by Scribner, Armstrong & Co. in 1873. Karen Montgomery produced the cover layout with Adobe InDesign CS using Adobe's ITC Garamond font. David Futato designed the interior layout. This book was converted by Keith Fahlgren to FrameMaker 5.5.6 with a format conversion tool created by Erik Ray, Jason McIntosh, Neil Walls, and Mike Sierra that uses Perl and XML technologies. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed; and the code font is LucasFont's TheSans Mono Condensed. The illustrations that appear in the book were produced by Robert Romano, Jessamyn Read, and Lesley Borash using Macromedia FreeHand MX and Adobe Photoshop CS. The tip and warning icons were drawn by Christopher Bing. This colophon was written by Nicole Arigo.