SSH - Few Words

SSH is a client and server protocol used to log in to another computer over a network. It provides strong authentication and secure communication over a public communication network. SSH may be “more” secure many vendors implementations of SSH is vulnerable.

So lets hop on to a router and configure it :)

Before We enable and configure ssh access, you should know that before enabling ssh we need to configure hostname on router other than "router" and also we need to configure "domain name" on router. Also ssh uses tcp port 22.

Router(config)#hostname Deepak

Deepak(config)#ip domain-name deepak.com

Deepak(config)#crypto key generate rsa general-keys

The name for the keys will be: Deepak.deepak.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]: Just hit enter here

% Generating 512 bit RSA keys, keys will be non-exportable...[OK]

Deepak(config)#

*Mar  1 00:03:13.563: %SSH-5-ENABLED: SSH 1.99 has been enabled

Next step is to allow ssh protocol on vty lines for access.

Deepak(config)#configure terminal
Deepak(config)#line vty 0-4
Deepak(config-line)#transport input ssh

Now lets hop on to last few steps. It includes creating local user database and also allowing local authentication on router.

Deepak(config)#username deepak password deepak

Deepak(config)#line vty 0 4

Deepak(config-line)#login local

Deepak(config-line)#exit

Now just hop on to client router and use following command for ssh access.

Test#ssh -l deepak 1.1.1.1 ( 1.1.1.1 is just ip address of destination router to which we need 

                                         access)