Blocking protocols at Layer 7 with the L7 patch
BEYOND THE PORT
If you need a tool for filtering protocols that doesn’t depend on the port, try L7, an IPTables patch that operates through regular expressions.
Traditional firewalls decide whether to allow or reject packets based on IP addresses, TCP flags, MAC addresses, ports, and other criteria that reside in OSI layers two through four. Experienced admins can probably type commands like iptables -A FORWARD -i $IF -o $OF -p tcp --dport 80 --syn -j ACCEPT standing on their heads. But what if the web server listens on port 8500 rather than port 80? Or if a gaming server misuses this port? Peer-to-peer applications are even worse, as there is no way of predicting the ports they will use. And VoIP makes the chaos complete with Real Time Protocol (RTP), which definitely takes liberties when assigning UDP ports.
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
News
-
GNOME 40 Beta has been Released
Anyone looking to test the beta for the upcoming GNOME 40 release can now do so.
-
OpenMandriva Lx 4.2 has Arrived
The latest stable version of OpenMandriva has been released and offers the newest KDE desktop and ARM support.
-
Thunderbird 78 is being ported to Ubuntu 20.04
The Ubuntu developers have made the decision to port the latest release of Thunderbird to the LTS version of the platform.
-
Elementary OS is Bringing Multi-Touch Gestures to the OS
User-friendly Linux distribution, elementary OS, is working to make using the fan-favorite platform even better for laptops.
-
Decade-Old Sudo Flaw Discovered
A vulnerability has been discovered in the Linux sudo command that’s been hiding in plain sight.
-
Another New Linux Laptop has Arrived
Slimbook has released a monster of a Linux gaming laptop.
-
Mozilla VPN Now Available for Linux
The promised subscription-based VPN service from Mozilla is now available for the Linux platform.
-
Wayland and New App Menu Coming to KDE
The 2021 roadmap for the KDE desktop environment includes some exciting features and improvements.
-
Deepin 20.1 has Arrived
Debian-based Deepin 20.1 has been released with some interesting new features.
-
CloudLinux Commits Over 1 Million Dollars to CentOS Replacement
An open source, drop-in replacement for CentOS is on its way.