Telnet allows you to connect to the Services Router and access the CLI to execute commands from a remote system. Telnet connections are not encrypted and therefore can be intercepted.
Telnet access to the root user is prohibited. You must use more secure methods, such as SSH, to log in as root.
If you are using a JUNOScript server to configure and monitor routers, you can activate clear-text access on the router to allow unencrypted text to be sent directly over a TCP connection without using any additional protocol (such as SSH, SSL, or telnet). Information sent in clear-text is not encrypted and therefore can be intercepted. For more information about the JUNOScript application programming interface (API), see the JUNOScript API Guide
SSH also allows you to connect to the router and access the CLI to execute commands from a remote system. However, unlike telnet, SSH encrypts the password so that it cannot be intercepted.
SSH connections are authenticated by a digital certificate. SSH uses public-private key technology for both connection and authentication. The SSH client software must be installed on the machine where the client application runs. If the SSH private key is encrypted (for greater security), the SSH client must be able to access the passphrase used to decrypt the key.
For information about obtaining SSH software, see http://www.ssh.com and http://www.openssh.com.