When we think of hardening we are really thinking of a process of securing a computer system or network by reducing its vulnerabilities to attacks. This can be done through a variety of measures, including enabling security features, configuring security protocols, updating software and firmware, and implementing best practices for password management and access control. Hardening a system can help protect against security threats such as malware, viruses, hacking, and unauthorized access. So If you are interested to see how it is done, please do read below!

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There are several steps you can take to harden Cisco Catalyst switches:

  • Enable security features: Make sure you have enabled security features such as access control lists (ACLs), port security, and private VLANs to restrict unauthorized access to your network. To create an ACL that allows only certain IP addresses to access the switch, use the following command: 
    switch(config)# ip access-list <name>
switch(config-acl)# permit <IP address>
  • Use strong passwords: Use strong, complex passwords for all user accounts on the switch and enable password aging to regularly change passwords. To create a local user account with a specific password, use the following command:

switch(config)# username <username> password <password>

To enable password encryption, you will need to enter this command in global configuration mode. Here’s an example of how you might use the “service password-encryption” command:

switch(config)# service password-encryption Once password encryption is enabled, all passwords that you enter into the configuration will be automatically encrypted and stored in the configuration file.

  • Configure security protocols: Configure security protocols such as SSH, TLS, and IPSec to encrypt communication between devices and protect against network attacks. Here are all of the commands that you need to use to enable SSH on a Cisco device:
crypto key generate rsa
hostname hostname
username username password password
ip domain-name domain-name
ip ssh version 2
interface interface
ip ssh server
ip ssh port port
  • Enable security logging: Enable security logging on the switch to record any security-related events and help identify potential threats. To enable security logging on the switch, use the following command:

switch(config)# logging on

  • Update the switch firmware: Keep the switch firmware up to date to ensure that it has the latest security patches and fixes. On Cisco Nexus Devices, you can use the following command:

switch# install all nxos <image file name>

  • Monitor the network: Regularly monitor your network for security threats and suspicious activity. To monitor a network using Simple Network Management Protocol (SNMP), you will need to perform the following steps:

Configure the device to act as an SNMP agent. To do this, you will need to use the following commands: snmp-server community community-string ro

  • Use VLANs: Use VLANs to segment your network and isolate different network segments from each other. This can help prevent unauthorized access and limit the impact of a security breach. Create a VLAN: To create a VLAN, you can use the following command: 
    switch(config)# vlan <VLAN ID>
switch(config-vlan)# name <VLAN name>

    Assign an interface to a VLAN: To assign an interface to a specific VLAN, use the following command:

    switch(config-if)# switchport mode access
switch(config-if)# switchport access vlan <VLAN ID>

    Create a trunk link: To create a trunk link between two switches that allows multiple VLANs to be transmitted over a single link, use the following command:

switch(config-if)# switchport mode trunk

Configure VLAN tagging: To configure VLAN tagging on a trunk link, use the following command:

switch(config-if)# switchport trunk allowed vlan <VLAN ID>

  • Use network access control: Use network access control technologies such as 802.1X and MAC filtering to control which devices are allowed to access your network. To configure 802.1X authentication on a Cisco device, you will need to use the “dot1x” command. Here is an example of how you might use this command to configure 802.1X authentication on a switch: 
    switch# configure terminal
switch(config)# dot1x system-auth-control
switch(config)# interface interface
switch(config-if)# dot1x port-control auto
switch(config-if)# end

    You will also need to configure the device to use a RADIUS or TACACS+ server to authenticate users. To do this, you can use the “radius-server” or “tacacs-server” command, as follows: switch(config)# radius-server host hostname key key

  • Secure management interfaces: Secure the switch’s management interfaces by limiting access to authorized personnel only and using strong passwords.

  • Use Network Address Translation (NAT): Use NAT to hide the IP addresses of internal devices from external networks, which can help protect against network attacks.

By following these best practices, you can help protect your Cisco Catalyst switches and the networks they support from security threats.

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