How to Secure Telnet Connections with Cisco Commands

What command would a network administrator use to allow only one Telnet connection and encrypt the password?

• A. (config)#service password-encryption
• B. (config)#line vty 0
• C. (config)#username USERNAME password PASSWORD
• D. (config-line)#login

Answer: (A)

The correct command to allow only one Telnet connection and ensure that the password is encrypted is related to the service password-encryption command. When this command is configured, it encrypts all plaintext passwords in the configuration file, thereby enhancing the security of the passwords used for accessing the device, including those for Telnet sessions. While the service password-encryption command secures passwords, managing Telnet connections is also critical. It is worth noting that to limit the number of concurrent Telnet connections, the network administrator would typically need to configure the terminal lines directly under-line vty settings and set appropriate limits. However, the command that directly contributes to password encryption—enhancing overall security—is indeed the service password-encryption command. In this context, while options related to line configuration or user authentication are relevant to session management, they do not specifically pertain to encrypting passwords alone, nor do they focus solely on limiting Telnet connections. The intention of the question is geared towards encryption, making the first command the most appropriate choice.

When it comes to networking and security, the right commands can make all the difference. Imagine a scenario where a network administrator is faced with the pressing need to secure Telnet connections. What’s the first thought that comes to mind? If you've prepared for the Cisco Certified Network Associate (CCNA) exam, you'd probably say, "I need to encrypt those passwords!" Well, you’re absolutely on the right track.

So, what command would you use? Here’s the key: (config)#service password-encryption is your golden ticket. This command ensures that any plaintext passwords within your configuration file are encrypted, providing a much-needed layer of security. Think of it as a safe that keeps your secrets under lock and key—only accessible to those who really need to know. Pretty neat, right?

Now, let's consider the importance of managing multiple Telnet connections. You've got your line vty 0 command on one hand and the capability to set limits on the number of concurrent connections. Remember, security isn’t just about passwords. It’s also about controlling who can access your system and how many can connect simultaneously. However, while (config)#line vty is certainly part of the equation, it's important to note that it doesn’t specifically focus on the password encryption aspect – that's where service password-encryption shines.

If we break it down a bit more, limiting the number of concurrent Telnet sessions would typically require adjusting terminal line settings. Yet, the focus of our initial question zeroes in on encryption, making that first command the star of the show!

It’s worth highlighting how crucial this knowledge is in a real-world context. A misunderstood command could expose sensitive configurations or lead to unauthorized access. No one wants that kind of headache, right? The benefit of being well-versed in these commands extends beyond the CCNA exam. It builds a foundation for best practices in network security.

But here’s something to ponder: In this age of smart devices and remote access, why rely solely on Telnet when SSH (Secure Shell) is available? It provides built-in encryption and secure channel establishment. Just a thought you might want to explore.

To sum it all up, while other commands related to user configuration and connection limits have their place, the command that stands out for securing passwords in Telnet sessions is undoubtedly (config)#service password-encryption. As you prepare for the CCNA exam, keep this in your toolkit—your future self (and your network) will thank you!