Hamming It Up On Linux
The first house has something very different about it, seen even without the binoculars. You can see a 50-foot tower looming high into the sky. On the structure are scores of antennas in every size and shape imaginable. As you “peer” into the den of the house, you see more electronic equipment than you would expect to find at the local radio station. There are dials, lights, LEDs, and meters of every kind. There are the sounds of Morse code, static, and eerie-sounding human (human?) voices. The man at the equipment has a microphone in front of him, and in his right hand there is a telegraph operator's key.
Now, moving to the second house, we see a typical home, like you'd expect in Anytown, USA. Nothing unusual as we approach it. So get out the binoculars! (Come on, get into the shadows. Someone will see us!)
In the den of this home, we find an ordinary-looking man sitting at his personal computer. His eyes seem a bit bleary, but he seems to be enjoying whatever it is that he is doing. Looking closer, you can see that the operating system is obviously Linux, as he swaps virtual consoles at the speed of light. But then he stops on one VC which seems to be an IRC-type chat group, but instead of “handles”, each VC is identified by a cryptic series of letters and numbers...
Okay, put the binoculars down. What do these two men have in common? They are both amateur radio operators. And amateurs have been migrating to Linux in remarkable numbers. In this article, I'll try to give the non-amateur a feel for why this is occurring, from an insider's viewpoint (yes, I'm one of them: KO4KS is my amateur radio callsign).
Without getting into the nitty-gritty details of it, the countries of the world cooperate together to provide radio spectrum for use by licensed operators for experimentation, public service, and just plain fun!
Amateurs have a wide variety of radio-related ways to enjoy their hobby. There is the traditional Morse code, shortwave, as well as local voice communications. In addition, among others, there are satellite communications, participation with the space program, and something called packet radio.
Most of you have probably seen e-mail addresses in the “ampr.org” domain. These are addresses of amateur radio operators, using packet radio. But how did they get on the Internet? Don't get ahead of me....
Packet radio is described by some as Ethernet over radio (though Ethernet used to be described as packet radio over wire). Anything you can do over Ethernet can be done over packet. Packet operators and programmers have been highly involved in many Internet RFCs as they have found ways around the problems encountered in using radio in this manner.
Packet radio uses a variation of the X.25 protocol called AX.25 (Amateur X.25). Their radios are connected to their computers with a little packet modem.
Initially, the “killer app” of packet radio was the Packet BBS (PBBS). PBBSs are pretty crude by today's BBS standards, but they pass messages internationally by means of thousands of individually owned radio sites that relay the mail, hop by hop along the way. Some packet PBBSs have HF (“High Frequency”--which, paradoxically, is at the very low end of the frequencies used for packet radio) ports for passing the mail over longer hops, but most hops are only a few miles each.
Then, several years ago, Phil Karn/KA9Q wrote a program called NET, to incorporate AX25 and TCP/IP together on computers running MS-DOS. As time progressed, NET became NOS (Network Operating System), which was now a multi-threaded application allowing multiple incoming and outgoing sessions. I am told that some commercial manufacturers have licensed the KA9Q code as a base for their development, and many of the new and modified protocols have made their way into commercial wireless TCP/IP networks.
Phil made his code available freely to amateurs and for educational purposes and even has allowed variations to spring up. There are many “xNOSs”, such as WNOS, JNOS, PMNOS, etc. and others that I'm sure I missed. I'm a little partial to Tampa NOS (TNOS), since I am the one who has developed this variation.
This interest in TCP/IP leads very naturally to Linux, but even more so when you consider the limitations of a program like xNOS under MSDOS. Good ol' DOS doesn't have a linear memory map, TCP/IP or multitasking built in. And it does have the 640K conventional memory barrier. It also requires dedicating a computer to xNOS under DOS.
Packet Radio Meets Linux
Linux is a good move for xNOS, since the DOS-related restrictions are gone. A couple of xNOSs have already been ported to Linux, including TNOS. Those interested can find it at ftp.lantz.com:/tnos/current/linux. For Web slingers, try www.lantz.com.
NOS under Linux is still a large program, with all of the same features as the DOS version, including its own TCP/IP stack. You can connect TNOS to the Linux TCP/IP stack by means of a ptty SLIP or PPP link.
Amateur Radio TCP/IP is passed over the real Internet by Amateur gateways. These gateways exist both on the Internet and on the local packet network. Other non-gateway Amateur packet stations can pass packets through the gateway to Amateur stations on the other side of distant gateways. This is done by encapsulating the 44.xx.xx.xx addresses (addresses assigned to the ampr.org domain) into “real” Internet addresses for passing through the backbones.
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.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.View Now!
|The Firebird Project's Firebird Relational Database||Jul 29, 2016|
|Stunnel Security for Oracle||Jul 28, 2016|
|SUSE LLC's SUSE Manager||Jul 21, 2016|
|My +1 Sword of Productivity||Jul 20, 2016|
|Non-Linux FOSS: Caffeine!||Jul 19, 2016|
|Murat Yener and Onur Dundar's Expert Android Studio (Wrox)||Jul 18, 2016|
- The Firebird Project's Firebird Relational Database
- Stunnel Security for Oracle
- My +1 Sword of Productivity
- SUSE LLC's SUSE Manager
- Managing Linux Using Puppet
- Non-Linux FOSS: Caffeine!
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader Released
- Doing for User Space What We Did for Kernel Space
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