The Illustrated Network- P69:In this chapter, you will learn about the protocol stack used on the global public Internet and how these protocols have been evolving in today’s world. We’ll review some key basic defi nitions and see the network used to illustrate all of the examples in this book, as well as the packet content, the role that hosts and routers play on the network, and how graphic user and command line interfaces (GUI and CLI, respectively) both are used to interact with devices. | CHAPTER 25 Secure Shell Remote Access 649 transfer would be done with sftp in the SSH implementation known as Tectia sftp is confusingly invoked with the command scp2 . The point here is that both methods will transfer the file as long as everything else is set up correctly. The best book on SSH SSH The Secure Shell by Daniel J. Barrett Richard E. Silverman and Robert G. Byrnes O Reilly Media is about as long as this one. Interested readers are referred to this text for more detailed information on SSH. SSH IN ACTION If there is one thing that was used more than FTP to produce this book it s SSH. In fact all of the file transfers used to consolidate output for these examples could just as easily have been done with SCP or SFTP. This is especially true when routers are the remote systems Only in special circumstances will organizations allow or use Telnet for router access. Let s use SSH to contact the routers on the Illustrated Network. Naturally the routers have been set up ahead of time to allow administrator access from certain hosts on LAN1 and LAN2 and are running sshd. But on the client side we ll run ssh out of the box and see what happens. Ethereal captures are not the best way to look at SSH in action. The secure and encrypted transfers make packet analysis difficult and often impossible . Fortunately we can use the debug feature of SSH itself to analyze the exchange in very verbose form using the -vv option . Let s see if we can catch SSH-TRANS SSH-AUTH and SSH-CONN in action when we access router TP2 from bsdclient. We ll log in the -l option as admin. bsdclient ssh -vv -l admin FreeBSD-20030924 SSH protocols OpenSSL 0x0090704f debug1 Reading configuration data etc ssh ssh_config debug1 Rhosts Authentication disabled originating port will not be trusted. debug1 ssh_connect needpriv 0 debug1 Connecting to port 22. debug1 Connection established. debug1 identity file root .ssh identity type .
