The http://www.meetdageeks.com is another blog I write for. A lot of the articles are duplicated between the two, but not always. Here is the latest update.

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According to this news report from
https://www.computerworld.com/s/article/9221717/PC_makers_should_brace_for_drive_shortages, hard drives will be in short supply for about a year. How can you get around that? There are several ways to do it. Some of which I have talked about a little before. Well you operate the computer without a hard drive. At first that seems ludicrous. but it is actually very viable. There are two ways that this can be done. Both are based on what is known as the PXE or pre-execution environment where the hardware in the network interface card can load all or part of an operating system into a computer from the network.

A major advantage of using diskless clients is that all software management can be one from virtually just one point. All software maintenance and upgrades are done on the server(s). That means, you do not have to send out a software technician to a user’s desk to maintain the software on their system. Reduced Information technology support costs. Secondly. You also have reduced hardware or infrastructure costs. No hard drives to go out and replace. Less down time for users if any not to be productive.  Thin clients are usually much less expensive than brand new computers. Also no time is wasted backing up client machines. A big savings on storage more or less. Even too older computers can be converted to thin clients therefore reducing the need to get rid of old hardware and be a bit more green. 

Originally, what would happen is that either from a floppy or firmware built into a network card could listen to the network to see if there were packets that could be used to load into a machine. You needed a domain name server commonly known as a DNS server and what was called a tftp server to send out the partial operating system  to the machines. That partial operating system allowed the computer getting the packets to act like a terminal server client. Sort of like the old days with the mainframes and the dumb terminals. The server does all the heavy lifting of running the software. Couple of open source examples are LTSP or Linux terminal server project (ltsp.org) and clonezilla/drbd (clonezilla.org). Both projects have advanced dramatically. Major school systems and even businesses are using such projects.  We use both ltsp and drbd in our setup. Each have their advantages. More information about setting up ltsp and xrdp can be found a www.instructables.com/member/computothought. AOE and ISCSI instructables are coming.

Next generation pxe or what is called gPxe. With gpxe the client computer nic can look to a web server to boot from. The traditional tftp server is no longer needed and therefor less system administration costs. The advantage of this is if you have access to a web server, you can boot from almost anywhere you have internet access. Also too instead of just being able to load in enough software to act as a thin client, you can act as a fat or full client. AOE (ATA over ethernet) and ISCSI (Internet small computer system interface) is now being used in many businesses to achieve this. The hard disks are pooled to have greater storage in what is called a SAN (Storage Area Network). The hard disk is on the cloud so to speak. Then you do not have to worry about hard drives with valuable data being stolen or confiscated.  A real security plus, but then sending data over the web unless secured in some way can have even bigger issues.

Just last night I set it up so that the cloning software could be loaded from anywhere that had access to our web server. So If I needed to back up client computers, I would point the settings of the gpxe capable network card to the web server and vuola you have an instant back up at your fingertips. No more going out and purchasing backup software for each system.  Of course the process can be automated also say late at night or during the day when the computer is at a lower usage. Perfect for a business.

So now a business can take the hard drives out of client machines and use them for backups. Less trips to purchase replacement hard drives. Or can I say, “What hard drive shortage?”.

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The basis of this article is based on the dialog from the movie known as “The hunt for the Red October”. In the movie, one of the key lines was I think “One ping and one ping only”. Pinging was a method by submarines equipped with sonar to detect what is around them. Normally you would use more than one ping. In computing we also have a program called ping that does the same thing to detect what is around on the network. There is a very powerful program called nmap that usually automates such activity. That usually takes some kind of administrative power to implement. We will be using a simple linux batch file (could be easily converted to other platforms) to detect what is around us. This tool is perfect for the home network. It will probably not detect what is known as “Man in the middle devices”, but at least you can see the visible systems on your network.

The code.

ping.sh: (do not forget “chmod +x ping.sh)

<br />
for i in {1..254}<br />
do<br />
ping 192.168.1.$i -c1 -w1 -v | grep "icmp_seq=1"<br />
done<br />

If you have a different network, you will have to change “192.168.1” accordingly, here again we are using the good old “grep” command to extract data from the return stream. it is our sonar scope. Let’s run it.

$ ./ping.sh
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.852 ms
64 bytes from 192.168.1.31: icmp_seq=1 ttl=64 time=0.260 ms
64 bytes from 192.168.1.99: icmp_seq=1 ttl=255 time=2.75 ms
64 bytes from 192.168.1.109: icmp_seq=1 ttl=64 time=0.261 ms
64 bytes from 192.168.1.115: icmp_seq=1 ttl=64 time=0.064 ms
$ _

Ok, there are five devices on the network. We need to know more. There is what is call DNS or “Domain naming service”. We can use the router to tell us what the ipaddresses maybe are known as.

The code.

nslookup.sh: (Do not forget to make it executable with chmod +x nslookup.sh”)

<br />
for i in {1..254}<br />
do<br />
nslookup 192.168.1.$i | grep name<br />
done<br />

Let’s run it.
$ ./nslookup.sh
1.1.168.192.in-addr.arpa name = my_network.
10.1.168.192.in-addr.arpa name = router2.
20.1.168.192.in-addr.arpa name = router3.
31.1.168.192.in-addr.arpa name = oesrvr1.
115.1.168.192.in-addr.arpa name = oesrvr104
$_

Notice the ipadresses are backwards, but we still can identify units on the network from the list. Two devices show up known as router2 and router3. I know that they are not connected to the network at this time. They just have reserved names in the router. The unit at 99 is actually the print server and should have a reserved name in the router, I can take care of that later. 109 is a temp machine I have set up to test some software. Now if there were any unknown numbers, they would need to be investigated immediately. Again you would need to change “192.168.1.” to work with your network.

There you are, two simple tools to check on your network.

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One nice thing is that if you find a page with a tool that you need, under certain circumstances, you can save the page for later use. In some cases, if it is going into an educational environment, the advertisements have to go away. That is what was done with this web page.

Before:

After editing the source code:

So there are more uses for knowing html, javascript, and css than for just creating your own web page.  One of many sites to get free code: http://www.free-javascripts.com.

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Frittata Pie (in progress)

Good day.

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