je v informatice označení protokolu používaného v počítačových sítích, který pomocí stejnojmenné aplikace umožňuje uživateli připojení ke vzdálenému počítači.


TELNET COMMUNICATION SNIFFINGThis article is all about telnet and attacks that are mostly directed to his functionality. The biggest security issue in telnet protocol is surely lack of encryption. Every communication from remote device to networking device that we are configuring is sent in plain text. Of course, that is big security issue and in situations where we use telnet we are making our command vulnerable to frame sniffing. Attacker can easily se what are we configuring on that device and furthermore he can se the password that we have used to connect to device and enter configuration mode.
TELNET BRUTE FORCE ATTACKTelnet protocol can be used by an attacker to gain remote access to a Cisco network switch or other vendors to of course. If we configure a login password for the vty lines and set the lines to require password authentication to have permission to access the switch we are still not secure. This vty password on the telnet lines provides only an essential and basic level of security to help protect the switch from unauthorized access. However, it is not a secure method of securing access to the vty lines. There are a lot of tools available that are able to launch a brute force password cracking attack against the vty lines on the switch.
DOS ATTACKAnother type of Telnet attack is the DoS – denial of service attack. DoS attacks in general is simply a way to disrupt the communication of two network devices by using all the bandwidth that they connection has to offer. To do so attacker sends many not useful and irrelevant data frames and in this manner suffocate the connection. The genuine communication will not be able to get across this connection and will not function. This sort of attack can be also used to prevent network administrators to telnet into their devices.