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
US / Canada
UK / Australia
News
-
Armbian 21.05 Now Available
The Armbian developers have released the latest update to the Debian-based Linux distribution geared for ARM and embedded devices.
-
StarLabs has Released Another Linux Laptop
A new 14" Linux laptop has been released by the company that created the 11" Star Lite and can be purchased with your choice of Linux distribution.
-
Ubuntu 21.04 Adds Support for Active Directory and Other Major Changes
In a bid to help make Linux more viable for the business desktop, Canonical adds support for Active Directory and a few other notable changes.
-
GNOME 40 Available on openSUSE
The rolling release edition of openSUSE, Tumbleweed, now offers the latest version of the GNOME desktop.
-
Apple M1 Hardware Support to be Merged into Linux Kernel 5.13
Linux users will be able to install their favorite distribution on Apple’s M1-based hardware.
-
KDE Launches the Qt 5 Patch Collection
To support and maintain a stable Qt 5 for KDE Gears and Frameworks, KDE will maintain a patch collection.
-
Linux Creator Warns Next Kernel Could be Delayed
Linus Torvalds has issued concern about the size of kernel 5.12 and possible delays for its release.
-
System76 Updates its Pangolin Laptop
System76 has released a much-anticipated AMD version of their most popular laptop, the Pangolin.
-
New Debian-Based Distribution Arrives on the Market
TelOS is a new Debian-based Linux distribution with a customized, touch-screen-ready KDE Plasma 5 desktop.
-
System76 Releases New Thelio Desktop
One of the most ardent supporters of open source hardware has released a new desktop machine for home or office.