Device Hardening - Router

 Device hardening is an important aspect of network security. It involves configuring network devices such as routers and switches to be more resistant to unauthorized access and potential threats. Below are steps to perform some common device hardening tasks, including password encryption, SSH configuration, restricting virtual terminal access, and disabling unused services on a Cisco router or switch:

1. Configure Password Encryption:

To ensure that passwords are stored securely in the configuration, enable password encryption:

bash
Router(config)# service password-encryption

This command encrypts plaintext passwords in the configuration.

2. Configure SSH (Secure Shell):

• Enable SSH to allow secure remote access to the device.

  bash
  Router(config)# hostname myrouter
  myrouter(config)# ip domain-name example.com
  myrouter(config)# crypto key generate rsa general-keys modulus 2048
  myrouter(config)# line vty 0 4
  myrouter(config-line)# transport input ssh
  

• The above commands set the device hostname, configure a domain name, generate an RSA key pair, and restrict remote access to SSH only.

3. Verify SSH Configuration:

You can verify the SSH configuration using the following commands:

bash
myrouter# show ip ssh
myrouter# show crypto key mypubkey rsa

4. Restrict Virtual Terminal (VTY) Access:

To restrict who can access the device via VTY lines, configure access control lists (ACLs) or use login banners.

• Example using ACLs:

  bash
  myrouter(config)# access-list 10 permit host 192.168.1.100
  myrouter(config-line)# line vty 0 4
  myrouter(config-line)# access-class 10 in
  

• Example using a login banner:

  bash
  myrouter(config-line)# line vty 0 4
  myrouter(config-line)# login local
  myrouter(config-line)# transport input ssh
  myrouter(config-line)# exec-timeout 10 0
  myrouter(config-line)# login block-for 60 attempts 3 within 120
  myrouter(config-line)# login delay 2
  myrouter(config-line)# banner login ^CUnauthorized access prohibited. ^C
  

5. Disable Unused Services:

Identify and disable any unused services or interfaces to reduce the attack surface. For example, to disable the HTTP server:

bash
myrouter(config)# no ip http server

To disable a specific interface (e.g., FastEthernet0/1):

bash
myrouter(config)# interface FastEthernet0/1
myrouter(config-if)# shutdown

Remember that device hardening is an ongoing process, and you should periodically review and update your security configurations to adapt to new threats and vulnerabilities.