Build a Better Firewall-Linux HA Firewall Tutorial
The final step in the process is generating the firewall scripts and installing them on the firewall cluster members. To keep the article short, I'm using the root user to install the Firewall Builder-generated firewall scripts on the firewall servers, but Firewall Builder also supports using nonroot users with proper sudo rights. This is covered in the on-line Users Guide.
Before you can install the rules on the cluster member, firewalls create a directory called /etc/fw on both lj-fw-1 and lj-fw-2 servers. This is the default location where Firewall Builder will install the generated firewall script.
As previously mentioned, the process where Firewall Builder converts the rules into a firewall script that will be run on the firewall is called compiling the rules. To compile and use the built-in installer to deploy the rules, click on the Install button at the top of Firewall Builder to launch the install wizard.
Click the check box next to the cluster name, and make sure the Install check boxes are selected for both lj-fw-1 and lj-fw-2. If there are any errors in the configuration, the compiler will display these; otherwise, you will see a dialog window (Figure 9) showing that the cluster was compiled successfully. When the cluster is compiled, a firewall for each member of the cluster is created and saved locally on the machine where Firewall Builder is running.
Clicking Next on this window launches the installer dialog window (Figure 10). Each firewall in the cluster will have its own installer window. The installer uses SCP to transfer the firewall script that was generated for the cluster member to the firewall. After the firewall script is copied, Firewall Builder logs in using SSH to run the script. The installer includes an option to run in verbose mode, which displays each command as it is being run on the remote firewall. After the install completes, a new installer appears for lj-fw-2, and the same process is repeated.
This article just skims the surface of using Firewall Builder to configure firewall clusters. You can find much more information in the Firewall Builder Users Guide, including how to install custom policies on an individual cluster member, which is available on-line at the NetCitadel Web site.
Mike Horn is the co-founder of NetCitadel LLC, the company that develops and supports Firewall Builder. He has worked on network and security technologies for more than 15 years at companies ranging from small startups to large global Internet Service Providers.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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