Why is telnet a security risk

Sometimes Telnet is used for remote management or the initial setup of network hardware. It can also be used to test or troubleshoot remote web or mail servers, as well as for accessing remote MUDs multi-user dungeon games and trusted internal networks. But since the development of Telnet came before the mainstream adoption of the Internet, it doesn't employ encryption.

So it's outdated security-wise. Although there are protocols that have effectively replaced Telnet, in rare instances, it's still necessary to access legacy equipment unsupported by more up-to-date protocols. Luckily, there are options for securing Telnet sessions—but first, a quick overview of how this protocol operates and where you might encounter it. Telnet provides users with a bidirectional interactive text-oriented communication system that utilizes a virtual terminal over an 8-byte connection.

User data is interspersed in-band with Telnet control information over the transmission control protocol TCP. Often, Telnet was used on a terminal to execute functions remotely. To connect to the server using the Telnet protocol, the user enters a command prompt by following this syntax: telnet hostname port.

The user then executes commands on the server by using specific Telnet commands into the Telnet prompt. Telnet sessions between the client and the server are not encrypted without a workaround. But if Telnet is long outdated and vulnerable to a security attack, why use it in the first place? The fun answer is, even geeks get nostalgic for the good old days. Enthusiasts of all stripes often share a penchant for outdated technology. Think of current day audiophiles who prefer vinyl listening to vinyl over streaming services.

And though Telnet communications are sent in plain-text, insecure and unencrypted, Kerberos can provide an encryption workaround while SSH can provide a Telnet alternative. Today this is absolutely not used anymore to administer servers and other PCs, since Telnet is insecure.

It might be used in very small private networks though. Telnet is still used on Internet Bulletin Board Systems. These are old forums that are text-only and can only be navigated using the keyboard. I'm not sure what "telnet client" means in this context, but i guess the windows firewall will accept outgoing connections on port Don't use telnet unless you really need to.

Use ssh instead outgoing. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Is enabling telnet a security concern? Ask Question. Asked 10 years, 4 months ago. Active 5 months ago. Viewed 16k times. Why is it that Vista comes with telnet disabled?

Accessing any networked session like this exposes the users to identity, password, and data theft. SSH protects user identities, passwords, and data from network snooping attacks, and allows secure logins and file transfers. SSH has practically replaced Telnet, and the older protocol is used these days only in rare cases to access decades old legacy equipment that does not support more modern protocols. And there are still organizations that simply do not care about security.

For Unix and Linux operating systems, the OpenSSH implementation comes free with the operating system and can be used to replace Telnet. The protocol is documented in RFC Together with our customers, our mission is to secure their digital business on on-premises, cloud, and hybrid ecosystems cost-efficiently, at scale, and without disruptions to their operations or business continuity.