SSH or Secure Socket Shell, is a network protocol that provides network administrators/engineers with a secure way to access a remote router, switch or other network device. Secure Shell provides strong authentication and secure encrypted data communications between two communicating network devices.
To enable SSH on cisco router or switch, issue the commands below:
routerX # conf t
rouerX (config) # ip domain-name <- Change to your own domain
routerX (config) # username password
routerX (config # crypto key generate rsa general-keys modulus 1024
routerX (config) # ip ssh version 2
Now, disabble telnet so SSH is the only method to remotely connect to the router or switch
routerX (config) # line vty 0 4
routerX (config) # login local
routerX(config-line) # transport input ssh
Here is a actual demo of those commands on Cisco Router
RouterX>en
RouterX>enable
RouterX#conf t
RouterX(config)#ip domain-name spidertip.com
RouterX(config)#username abdi password cisco
RouterX(config)#crypto key generate rsa
The name for the keys will be: RouterX.spidertip.com
Choose the size of the key modulus in the range of 360 to 2048 for your
General Purpose Keys. Choosing a key modulus greater than 512 may take
a few minutes.
How many bits in the modulus [512]: 1024
% Generating 1024 bit RSA keys, keys will be non-exportable...[OK]
RouterX(config)#ip ssh version 2
RouterX(config)#
RouterX#copy running-config startup-config
RouterX#
RouterX#conf t
Enter configuration commands, one per line. End with CNTL/Z.
RouterX(config)#line vty 0 4
RouterX(config-line)#login local
RouterX(config-line)#transport input ssh
RouterX(config-line)#
