These protocols can also be used for other types of keyboard-based interactive session. In particular, there are a lot of bulletin boards, talker systems and MUDs (Multi-User Dungeons) which support access using Telnet. There are even a few that support SSH.
You might want to use SSH, Telnet or Rlogin if:
•you have an account on a Unix or VMS system which you want to be able to access from somewhere else
•your Internet Service Provider provides you with a login account on a web server. (This might also be known as a shell account. A shell is the program that runs on the server and interprets your commands for you.)
•you want to use a bulletin board system, talker or MUD which can be accessed using Telnet.
You probably do not want to use SSH, Telnet or Rlogin if:
•you only use Windows. Windows computers have their own ways of networking between themselves, and unless you are doing something fairly unusual, you will not need to use any of these remote login protocols.
1.2 How do SSH, Telnet and Rlogin differ?
This list summarises some of the differences between SSH, Telnet and Rlogin.
•SSH (which stands for ‘secure shell’) is a recently designed, high-security protocol. It uses strong cryptography to protect your connection against eavesdropping, hijacking and other attacks. Telnet and Rlogin are both older protocols offering minimal security.
•SSH and Rlogin both allow you to log in to the server without having to type a password. (Rlogin's method of doing this is insecure, and can allow an attacker to access your account on the server. SSH's method is much more secure, and typically breaking the security requires the attacker to have gained access to your actual client machine.)
•SSH allows you to connect to the server and automatically send a command, so that the server will run that command and then disconnect. So you can use it in automated processing.
The Internet is a hostile environment and security is everybody's responsibility. If you are connecting across the open Internet, then we recommend you use SSH. If the server you want to connect to doesn't support SSH, it might be worth trying to persuade the administrator to install it.
If your client and server are both behind the same (good) firewall, it is more likely to be safe to use Telnet or Rlogin, but we still recommend you use SSH.
Chapter 2: Getting started with PuTTY
This chapter gives a quick guide to the simplest types of interactive login session using PuTTY.
•
2.1 Starting a session
•
2.2 Verifying the host key (SSH only)
•
2.3 Logging in
•
2.4 After logging in
•
2.5 Logging out
2.1 Starting a session
When you start PuTTY, you will see a dialog box. This dialog box allows you to control everything PuTTY can do. See
chapter 4
for
details of all the things you can control.
You don't usually need to change most of the configuration options. To start the simplest kind of session, all you need to do is to enter a few basic parameters.
In the ‘Host Name’ box, enter the Internet host name of the server you want to connect to. You should have been told this by the provider of your login account.
Now select a login protocol to use, from the ‘Connection type’ buttons. For a login session, you should select Telnet, Rlogin or SSH. See
section 1.2
for a description of the differences between the three protocols, and advice on which one to use. The fourth
protocol, Raw, is not used for interactive login sessions; you would usually use this for debugging other Internet services (see