Technology: Security
Area: Device Hardening
Vendor: Cisco
Title: How to allow SSH only to Cisco device
Software: 12.X , 15.X
Platform: Catalyst switches, Routers

Secure Shell (SSH) is a protocol used when one wants to have vides a secure remote access connection to network devices. Communication between the client and server is encrypted in both SSH version 1 and SSH version 2. Implement SSH version 2 when possible because it uses a more enhanced security encryption algorithm. To restrict the device to accept only ssh connections (no telnet), use configuration below.

Switch# configure terminal
Switch(config)#line vty 0 15
Switch(config-line)#transport input ssh

Verifying if the ssh connection is working:

PC> ssh -1 admin 192.168.2.1
Open
Password:

Verifying if telnet connection is possible

PC> telnet 192.168.2.1
Timeout.....