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Linux Annoyances for Geeks by Michael Jang

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Users Are Still Demanding Telnet

Telnet is an old protocol that allows users to log in to remote systems in almost the same way as they log in to local text terminals. Security experts have been warning users about Telnet for decades and telling people to use a more modern protocol, such as the Secure Shell (SSH).

The main problem with Telnet is that it sends messages in clear text. In other words, anyone with a protocol analyzer (more popularly known as a "sniffer") and a connection to your network can read all network traffic that uses the Telnet protocol. They can even capture the username and password that are sent when someone logs in and then impersonate that user. Naturally, you don't want users making their passwords so easily accessible to crackers—or even the curious.

But many users are familiar and comfortable with Telnet, and want to use it despite its security problems. Many administrators like the way Telnet is configured as an Internet Super Server (inetd.conf or xinetd.conf) service. Fortunately, there are secure ways to configure Telnet. These methods use the Kerberos protocol, developed at MIT, to encrypt communications. There are two stages to this process: first, you'll need to install Kerberos clients and servers, with appropriate keys; then you can install the Kerberos-enabled Telnet clients and servers. I assume you'll want to install both clients and servers on your Kerberos/Telnet server computer, so you can test the results locally.

Tip

Treat the solution ...

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