How to Configure SSH (Secure Shell) on Cisco Devices

What is SSH (Secure Shell)?

Secure Shell (SSH) is a protocol which provides 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.

Set Up an IOS Router or Switch as SSH Server

There are five steps required to enable SSH support on a Cisco IOS router:

• Configure the hostname command.
• Configure the DNS domain.
• Generate the SSH key to be used.
• Enable SSH transport support for the virtual type terminal (vtys).
• Create username and password.

Step-1. Configure Hostname.

Router(config)#hostname R1

Step-2. Configure Domain Name

R1(config)#ip domain-name cisco.com

Step-3. Generate RSA Key

R1(config)#crypto key generate rsa
It will ask you for key module by default 512.
How many bits in the modulus [512]: 1024

Step-4. Specify SSH version.

R1(config)#ip ssh version 2

Step-5. Enable SSH transport support for the VTY

R1(config)#line vty 0 4
R1(config-line)#transport input ssh
R1(config-line)#login local

Step-5. Create username and password

R1(config)#username admin password cisco

Now try to connect with Putty or Secure CRT.