What Does telnet Mean
Telnet is the acronym for Telecommunication Network . It is the name of a network protocol used to access and operate a computer remotely. The term also allows to name the computer program that the client implements.
Access to another computer is done in terminal mode (without any type of graphical interface) and allows remote troubleshooting, so that the technician can deal with the problem without having to be physically next to the equipment in question. Telnet also makes it possible to remotely query data or start a session with a UNIX machine (in this case, multiple users can simultaneously log in and work with the same computer).
Another use that is given to this protocol is linked to access to the Bulletin Board System (BBS) , an announcement system that was the forerunner of today's Internet forums .
The main problem with telnet is its security flaws . Information travels across the network unencrypted, allowing a spy to access data such as usernames and passwords. That is why Secure Shell (SSH) emerged in the mid- 1990s , as a kind of encrypted telnet.
The SSH protocol, which represents a more secure alternative, performs the encryption of the information prior to its transmission, and also authenticates the computer with which it tries to connect. It also enables more sophisticated user data verification than telnet. Of course, to offer this extra flow of benefits it also requires more resources; in other words, a network that implements SSH must have more powerful machines than those used for telnet.
The little security that telnet offers can be explained by analyzing its history. When this protocol was developed (in the late 1960s ), networked computers were located in academic institutions or government offices; therefore, it was not necessary to invest resources in data encryption , since no one outside these establishments had access to their computers.
PuTTY is the name for a popular application that offers services such as serial terminal communications , telnet, SSH, rlogin, and secure file transfer over SFTP and SCP. It is worth mentioning that it is free and open source, in addition to providing its users with a high degree of customization. Regarding the supported operating systems, it supports all versions of Windows from 95, Unix and Mac OSX.
Rudiments of a telnet connection
When you want to start a session from a remote computer , you can use the telnet command accompanied by the IP address or the name of the destination computer; for example, to establish a connection to the machine tests.mydomain.com, the required command line is: telnet tests.mydomain.com . The same would be done in case of having your IP address: telnet 0.1.2.3 .
Having established the connection successfully, it is time to provide the username and password to start a session in text mode (a virtual console without a graphical interface, which allows you to control the remote computer through commands written).
As mentioned in previous paragraphs, the data that is transmitted through a connection that works according to the telnet protocol does not have any type of protection or encryption. This gives other users the possibility to view them if they manage to access them through hacking techniques (from the English term "hack", which in this case means "to gain access to a computer or application without permission"), without having to bother in deciphering them. It should be mentioned that programs or devices known as packet analyzers or packet sniffers are used to carry out this practice of piracy .