Using Firewall Builder, Part I
Believe it or not, even after all this work we're not done configuring the firewall object. In Figure 4 you may have noticed that in the hierarchical view of objects on the left-hand side of the window, the firewall Trillian has two interfaces, eth0 and lo. The eth0 subsection was created automatically when I ran the Insert firewall dialog. lo, which represents Trillian's loopback interface, had to be created manually. It's a little odd that its creation doesn't happen automatically. Every firewall, whether a multihomed host or a bastion host, needs rules that allow its loopback interfaces free rein (so local processes aren't interrupted).
To add a loopback interface manually, select your firewall object's icon in the object list, pull down the Insert menu above and select Interface. The Interface option is grayed-out unless you've selected a Host or Firewall object. A new interface icon appears below your firewall object, and the new interface's properties are displayed on the right. Enter the interface's name into Name (for example, lo), and deselect This Interface is External (insecure). The latter option should be checked only for your external interface and DMZ interface objects.
Next, while the new interface's object is still selected, pull down the Insert menu again and select Address. Now an address sub-object appears below your new interface, and its properties are displayed on the right (Figure 6). Enter a name, an IP address of 127.0.0.1 and a netmask of 255.0.0.0 (the latter will be filled in automatically, actually). In some circumstances, systems have more than one loopback interface, in which case the address may vary (127.0.0.2, etc.). Chances are, though, you have only one and its IP is 127.0.0.1. When in doubt, do an ifconfig -a on your firewall.
Once you've defined all your objects, or at least enough to start writing rules, save them by pulling down the File menu and selecting Save. You'll be prompted to provide a filename with a suffix of .xml in your home directory. Some scripts expect objects to be named objects.xml and to be stored in ~, but this is user-configurable. In other words, name your objects file whatever you like and put it wherever you want. Remember what and where these are if you need to tweak fwb_install or another policy installation script.
I'll leave it to you to create additional Host, Network and Firewall objects pertinent to your environment. Also, I've skipped Network Range and Time objects, both of which are easy to understand and use—you can figure these out by playing with them or by referring to the documentation at www.fwbuilder.org. Next month, we'll use all these objects to build some policies. In the meantime, I hope you've learned enough to get started and to start exploring Firewall Builder on your own. Have fun!
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
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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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide