In the "old days," people used telnet to access their systems remotely. Nowadays they can't do this: telnet sends its passwords in plain text over the network, and because too often these packets are transmitted across an insecure network, this really is not an option. It is simple for someone with a packet analyzer such as Ethereal to grab packets and read your username and password from the network. Therefore, new methods of remotely accessing a server have been created. I'll discuss two of these techniques in this chapter. First you will learn how to use Secure Shell (SSH) to set up a secure (read: encrypted) connection with a server. Next, you will learn how you can use VNC to get access to the graphical display of your server remotely. VNC isn't secure by itself, but in this chapter you'll learn how to combine it with SSH to make it secure. In this chapter, I'll cover the following subjects:
Understanding how SSH works: I'll explain how SSH uses encryption keys to establish secure remote sessions. Also, you will learn how to use SSH.
Configuring SSH: I'll explain how you can use the sshd_config and ssh_config files to tune how SSH works.
Configuring SSH key-based authentication: You will learn how to secure SSH even more by using public/private key technology for authentication.
Tunneling traffic with SSH: I'll explain how to establish a simple VPN connection between hosts using SSH.
Using VNC: You'll learn how to use VNC to get remote access to the server's graphical display.
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