Telnet vs. SSH - Part 1
When connecting remotely to a Cisco device you have a number of communication options: telnet, SSH, HTTP, HTTPS, etc. Since most of your communications will be of the command line variety via a terminal emulator, you will want to use either telnet or SSH (Secure Shell). This short video lesson looks specifically at security differences between telnet and SSH. Telnet has been around for over 40 years and is probably the most widely used method of remotely accessing Cisco devices. The big problem with Telnet is that is sends all traffic in plain text (unencrypted). Telnet does not encrypt any data sent over the connection (including passwords). This means that if someone is able to intercept that traffic, then they have access to all communications including PASSWORDS. SSH allows a strong encryption to be used with the Cisco IOS software authentication, so that same hacker will have a lot of work on his hands if he wants to try and decode your encrypted communications. Due to the added security that comes with encryption, Cisco recommends SSH be used instead of Telnet.
When connecting remotely to a Cisco device you have a number of communication options: telnet, SSH, HTTP, HTTPS, etc. Since most of your communications will be of the command line variety via a terminal emulator, you will want to use either telnet or SSH (Secure Shell). This short video lesson looks specifically at security differences between telnet and SSH. Telnet has been around for over 40 years and is probably the most widely used method of remotely accessing Cisco devices. The big problem with Telnet is that is sends all traffic in plain text (unencrypted). Telnet does not encrypt any data sent over the connection (including passwords). This means that if someone is able to intercept that traffic, then they have access to all communications including PASSWORDS. SSH allows a strong encryption to be used with the Cisco IOS software authentication, so that same hacker will have a lot of work on his hands if he wants to try and decode your encrypted communications. Due to the added security that comes with encryption, Cisco recommends SSH be used instead of Telnet.