Mac OS X Unleashed

By John Ray and William C. Ray

• Table of Contents
  • Copyright
  • About the Author
  • Acknowledgments
  • Tell Us What You Think!
  • Introduction
  • Part I: Introduction to Mac OS X
  • Chapter 1. Mac OS X Component Architecture
  • Chapter 2. Installing Mac OS X
  • Chapter 3. Mac OS X Basics
  • Chapter 4. The Finder: Working with Files and Applications
  • Chapter 5. Running Classic Mac OS Applications
  • Part II: Inside Mac OS X
  • Chapter 6. Native Utilities and Applications
  • Chapter 7. Internet Communications
  • Chapter 8. Installing Third-Party Applications
  • Part III: User-Level OS X Configuration
  • Chapter 9. Network Setup
  • Chapter 10. Printer and Font Management
  • Chapter 11. Additional System Components
  • Part IV: Introduction to BSD Applications
  • Chapter 12. Introducing the BSD Subsystem
  • Chapter 13. Common Unix Shell Commands: File Operations
  • Part V: Advanced Command-Line Concepts
  • Chapter 14. Advanced Shell Concepts and Commands
  • Chapter 15. Command-Line Applications and Application Suites
  • Chapter 16. Command-Line Software Installation
  • Chapter 17. Troubleshooting Software Installs, and Compiling and Debugging Manually
  • Chapter 18. Advanced Unix Shell Use: Configuration and Programming (Shell Scripting)
  • Part VI: Server/Network Administration
  • Chapter 19. X Window System Applications
  • Chapter 20. Command-Line Configuration and Administration
  • Chapter 21. AppleScript
  • Chapter 22. Perl Scripting and SQL Connectivity
  • Chapter 23. File and Resource Sharing with NetInfo
  • Chapter 24. User Management and Machine Clustering
  • Chapter 25. FTP Serving
  • Chapter 26. Remote Access and Administration
    • Security-Minded Thinking
    • What Is Secure Shell?
    • Starting SSH in OS X
    • Using SSH: From Unix Box to Unix Box
    • Using an SSH2 Client in Mac OS
    • Using an SSH1 Client in Mac OS
    • Public Key Authentication
    • Are There Any Graphical SSH Clients for OS X?
    • Are There SSH Clients Available for the PC?
    • Summary
  • Chapter 27. Web Serving
  • Part VII: Server Health
  • Chapter 28. Web Programming
  • Chapter 29. Creating a Mail Server
  • Chapter 30. Accessing and Serving a Windows Network
  • Chapter 31. Server Security and Advanced Network Configuration
  • Chapter 32. System Maintenance
  • Appendix A. Command-Line Reference
  • Appendix B. Administration Reference

What Is Secure Shell?

Secure shell is a common term used to describe a secure remote login protocol. Anyone using the term secure shell is also referring to the SSH protocol. In particular, the SSH protocol encrypts traffic and permits tunneling; that is, port forwarding over a secure channel.

There are two SSH protocols: SSH1 and SSH2. As you might have guessed, SSH1 is the original protocol, and SSH2 is a later development. Currently, SSH2 is the protocol under development. Where possible, use the SSH2 protocol rather than the SSH1 protocol. However, there are still Unix machines out there running only SSH1 servers. Consequently, we will discuss using both protocols. In most areas, the usage is similar.

The SSH protocol was originally developed by Tatu Ylonen, the chairman of SSH Communications Security, Ltd. The product was further developed by SSH Communications Security and F-Secure Corporation (formerly Data Fellows). Both companies still work on the protocol. F-Secure has marketing rights and rights to further modify the code. The SSH2 servers from these companies are similar.

There is also an SSH open source project called OpenSSH. It is also based on Tatu Ylonen's SSH. OpenSSH provides support for both SSH1 and SSH2 protocols. There is little noticeable difference in using one of the SSH servers from one of the companies and the OpenSSH package.

Because you now have the power of Unix, our examination of SSH will include not only what you need to know to connect to your OS X machine, but also what you need to know to connect to other Unix boxes that might be running the other SSH packages. As security concerns grow throughout the Internet community, using secure shell as a telnet replacement is becoming more common. Consequently, it is worthwhile to learn general basic SSH usage.

Share This