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.
Read full article as PDF:
Bridgewall_Firewalling.pdf (338.96 kB)Tag Cloud
News
-
An Even Smaller Raspberry Pi
The Raspberry Pi Foundation has announced an even smaller version of the tiny computer that will fit into a DIMM slot.
-
Newly Discovered Android Vulnerability Causes Privilege Escalation
A new class of problems lets a malicious app pre-configure an invisible privilege update.
-
Facebook Rolls Out New PHP-like Programming Language
New Hack language adds static typing and other conveniences.
-
Fedora Announces Innovative Crytography Policy System
New crypto policy system will offer easier configuration and more uniform security.
-
Shuttleworth Calls for Declarative Firmware
Ubuntu founder denounces insecurity in proprietary, close-source software blobs.
-
New TLS Attack Takes the S out of HTTPS
Vulnerability affects many Linux web servers
-
Munich Adopts Kolab
The Bavarian capital shuns Microsoft, Google, and other alternatives to implement an open source groupware solution.
-
Canonical Announces Ubuntu Smartphones
Phone vendor partnerships bring Mark Shuttleworth's dream of Ubuntu on a phone a step closer to reality.
-
Piviti Seeks Funding
Donors will get to vote on new features for the free video editor.
-
Debian Tech Committee Votes for systemd
Debian project puts init out to pasture and says no to Ubuntu's Upstart.