This error means that there has been an attempt to connect to this router using remote shell. (Remote shell is a program that lets users connect to systems remotely, similar to telnet). In this case, since your router is not configured as a remote shell server, the connection attempt has been denied.
This is just a warning message, but if the attempt is from an unauthorized machine, it is advisable to monitor the activities from this machine for possible security attacks.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...