Implementing a bridging-level firewall
The Drawbridge
Firewalls are typically implemented as routers,but it doesn’t have to be that way. Bridging packet filters have a number of advantages,and you can add them to your network at a later stage without changing the configuration of your network components.
Linux has earned a reputation as an excellent firewall platform. The kernel has a powerful Netfilter/ IPtables-based packet filter. In a traditional firewall scenario, Netfilter resides on a router, where it subdivides the network into two or more subnets. But adding a firewall to an established network can involve changing the network infrastructure. This effort can result in IP address changes and modifications to access controls for internal services. It is far simpler to add a bridge. Bridges reside in layer 2 of the OSI reference model and normally inspect MAC addresses rather than IP addresses (see the box titled “Building Bridges”). Linux can leverage this capability in a clever way to add transparent firewalling to a network. Of course, the bridge evaluates packets from the higher protocol layers (IP addresses, TCP ports) in its role as a firewall. But the hosts on the network will not notice a thing, unless they attempt to send illegal packets.
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
News
-
Kali Linux 2019.1 Released
The favorite Linux distro of Mr. Robot gets the first update of 2019.
-
Linux Foundation Releases a New Draft of OpenChain Spec
OpenChain provides a standard for open source compliance throughout the software supply chain.
-
Linux Kernel Continues To Offer Mitigation for Spectre Mitigation
Kernel 4.19 has added another family of Spectre vulnerabilities to its list of mitigating the mitigation.
-
SpeakUp Trojan Targets Linux Servers
It’s exploiting a known vulnerability.
-
KDE Plasma 5.15 Beta Arrives
Major improvements to software management.
-
Canonical Announces Latest Ubuntu Core for IoT
Now offers 10 years of support.
-
GitHub Offers Free Private Repositories
Popular source code collaboration site makes a major change to feature set.
-
Linus Torvalds Welcomes 2019 with Linux 5.x
Better support for GPUs and CPUs.
-
Keep your edge with these powerful Linux administration tools:
Keep All Your Linux Servers in Check
Watching the Bad Guys with Cowrie
Become a certified Linux Admin professional with the Linux Professional Institute LPIC-1 Systems Administrator certification.
-
Microsoft Gets an Open Source Web Browser
The company will use Google Chromium web browser as the foundation for its next browser.