Use of SSH or VTY ACLs.
The command is bad configurate.
rsh and ssh are similar in that they can execute commands on remote systems. The main difference between the two (besides the actual TCP ports) is that rsh traffic is not encrypted and therefore a security risk; ssh traffic is encrypted. The other main difference is that ssh is a secure replacement for telnet, whereas rsh can log into a remote system using the rlogin protocol, which is similar but not the same as telnet.
show sessions
SSH is more secure than Telnet.
what osi layers use telnet connections for remote use
FTP and Telnet are similar in that they are defined as OSI layer 7 (application) protocols. They are different in that they use different ports for sending and receiving messages and are used for different purposes. FTP is used to sending and receiving files across a network. Telnet is used to send commands remotely to another network device.
ssh
If you want better security, use secure shell (ssh) instead of telnet. Actually, don't use telnet at all if possible, as it transmits all information in plain text.
Telnet is non secure, travel data in open form you can easily theft/capture data, ssh is secure transmission of data over network, telnet is little bit faster than SSH, because it is not encrypting data, SSh is little slower than telnet because encrypt data when transmitting over network
Port 443 is used for Hypertext Transfer Protocol Secure connections, whereas port 80 is used for Hypertext Transfer Protocol connections. Hypertext Transfer Protocol Secure connections are more secure and can protect against attacks.
ssh protocol
One disadvantage of telnet is that it is not secure, meaning people can read your passwords and other sensitive information. It is outdated and has no colors. It is fairly hard to use.