Creating a Bridge Firewall with DSA Switch: A Successful Attempt?

Creating a Bridge Firewall with DSA and Switch: A Successful Attempt

In this article, we will discuss the process of creating a bridge firewall using DSA (Distributed System Architecture) and a switch. We will provide a detailed walkthrough of the steps involved in the process, along with subtitles and code blocks to help you understand the key concepts.

Introduction

A bridge firewall is a security mechanism that controls the flow of traffic between different networks. It is typically used to isolate a secure network from an insecure one, such as the internet. A bridge firewall can be implemented using a variety of technologies, including DSA and switches.

Prerequisites

Before we begin, it is assumed that you have a basic understanding of networking concepts, as well as experience working with switches and routers. Additionally, you will need access to a switch that supports DSA, as well as a router or other device that you can use as the bridge firewall.

Setting up the Switch

The first step in creating a bridge firewall is to set up the switch. This involves configuring the switch to support DSA and creating the necessary VLANs (Virtual Local Area Networks).

switch# configure terminal
switch(config)# system qos
switch(config-qos)# service-policy input QOS-IN
switch(config-qos)# service-policy output QOS-OUT
switch(config-qos)# exit
switch(config)# vlan 10
switch(config-vlan)# name Internal
switch(config-vlan)# exit
switch(config)# vlan 20
switch(config-vlan)# name External
switch(config-vlan)# exit
switch(config)# interface vlan 10
switch(config-if)# ip address 192.168.1.1 255.255.255.0
switch(config-if)# exit
switch(config)# interface vlan 20
switch(config-if)# ip address 192.168.2.1 255.255.255.0
switch(config-if)# exit
switch(config)# interface ethernet 1/1
switch(config-if)# switchport mode trunk
switch(config-if)# switchport trunk allowed vlan 10,20
switch(config-if)# exit

Setting up the Bridge Firewall

Once the switch is set up, the next step is to configure the bridge firewall. This involves creating a bridge interface on the router and configuring the necessary access control lists (ACLs) to control the flow of traffic.

router# configure terminal
router(config)# interface bridge 1
router(config-if)# bridge-domain 10
router(config-if)# bridge-domain 20
router(config-if)# exit
router(config)# ip access-list extended INPUT
router(config-ext-nacl)# permit ip 192.168.1.0 0.0.0.255 any
router(config-ext-nacl)# deny ip any any
router(config-ext-nacl)# exit
router(config)# ip access-list extended OUTPUT
router(config-ext-nacl)# permit ip any 192.168.2.0 0.0.0.255
router(config-ext-nacl)# deny ip any any
router(config-ext-nacl)# exit
router(config)# interface ethernet 0/0
router(config-if)# no ip address
router(config-if)# no shutdown
router(config-if)# bridge-group 1
router(config-if)# exit

Testing the Bridge Firewall

Once the bridge firewall is set up, it is important to test it to ensure that it is working correctly. This can be done by attempting to ping a host on the internal network from the external network, and vice versa. If the pings are successful, then the bridge firewall is working correctly. If not, then there may be an issue with the configuration that needs to be addressed.

Creating a bridge firewall using DSA and a switch is a relatively straightforward process, but it is important to ensure that it is set up correctly in order to ensure the security of the network. By following the steps outlined in this article, you should be able to create a functional bridge firewall that can be used to isolate your secure network from an insecure one.

• A bridge firewall is a security mechanism that controls the flow of traffic between different networks.
• A bridge firewall can be implemented using a variety of technologies, including DSA and switches.
• Setting up the switch involves configuring it to support DSA and creating the necessary VLANs.
• Setting up the bridge firewall involves creating a bridge interface on the router and configuring the necessary ACLs.
• It is important to test the bridge firewall to ensure that it is working correctly.

References

• Cisco Catalyst 6500 Series Switch: Configuring Bridging
• Distributed System Architecture (DSA) Overview
• Configuring VLANs on a Catalyst 6500 Series Switch