Brought to you each week by the PC Gurus, a loose collection of volunteers from around the Kentuckiana region.
You can interact with the team via chat room or BBS at www.thepcgurus.com. There are usually members present in the chat room after 8:00 PM every evening and you can post computer questions, comments, rants etc. on the bulletin board 24/7.
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The WHAS Crusade for Children provides year round support for needy children throughout the Kentuckiana region. Visit http://www.whascrusade.org to make donations online.
5-26-05
An email question about an IP conflict earlier this week prompted me to peruse our back issues and I discovered that we have never addressed how the Internet is… addressed ;) How your mail servers know where to send you messages, how your browser knows where to look for web pages and so on. With billions of connected computers, servers, domains and so on there has to be a logical addressing method, and that method is called TCP/IP.
Transmission Control Protocol/Internet Protocol is a system made up of 32 bits of binary information represented as xxx.xxx.xxx.xxx, where each octet represents a number from 0 to 255. I’m not going to delve to deep here but there are different “classes” of addresses with A, B and C being used for standard addressing on the Internet and D and E being used for multicast and experimental purposes.
Some specific addresses are set aside for specific uses and can’t serve as true Internet addresses. As we learned a few weeks ago 127.0.0.1 is a loopback address for testing purposes, and for tripping up moronic script kiddies ;) There are also ranges set aside for internal networks, for example 10.xxx.xxx.xxx and 192.168.xxx.xxx. If you have a broadband connection and use a router to share it you should recognize those ranges.
Linksys routers, as an example, are preset to 192.168.1.1, with DHCP enabled to assign addresses from 192.168.1.100 to 192.168.1.199 to devices that connect to the router. DHCP assigns the addresses automatically, or dynamically, so that any time you turn your PC on the router gives it an address from the pool available. This is also used by ISPs so end users don’t have to jump through lots of hoops to set up their connection.
The other type of addressing is static, meaning they never change. Those addresses are used for Internet servers and domains for websites as well as internal network addresses that need certain incoming data forwarded through the router to a specific PC.
Down deep what all this means is that anything connected to the Internet has to have a unique address, much like the street address for your house or place of business. For an analogy, let’s say you want to order a Crutchfield catalog to be mailed to your house. You look in the Yellow Pages for the phone number of Crutchfield for the phone number, then call and give them your address so they can send the catalog to the right location.
On the Internet you type www.crutchfield.com into your browser and your ISP consults one of the “yellow pages” machines on the Internet, which host the DNS “lookup tables”. DNS is Domain Name Service and the tables are basically huge repositories of the binary addresses, or phone numbers, of every website available. The DNS server finds the number, which in this case is 12.4.198.133, and forwards the ISP to that location. The ISP passes along your request for information and instructs Crutchfield to send the information to your unique address. The information is addressed to your PC or “house” and voila, the page comes up on your screen.
Now to the entire reason this topic came up, and an answer that may explain a problem you’ve noticed yourself.
The question was, to paraphrase, why do I have to reboot my PC when I get home from work if I turn off my cable modem?
If you don’t use a router the IP address of your PC is the same as that of your broadband modem. When you first fire up the PC it asks the modem for that address and assigns it as it’s “home”. By turning the modem off but leaving the PC on, the PC retains that original address. In a dynamic environment like most cable systems, when you turn the modem back on it gets a new address, which requires the PC to acquire the new address and rebooting is the simplest solution.
See how easy that was?
Next week I’ll explain how a home router balances the load between the address of the modem and the addresses of multiple PCs on the internal network. Try to contain your excitement;)
Kevin Mefford, Editor
In response to
its poor information sharing habits prior to the 9/11
attacks the FBI is
working on Sentinel, a computer network designed
to help the agency better
communicate with itself and other
law-enforcement types:
http://news.com.com/FBI+to+launch+new+computer+system+by+2006/2100-7348_3-5719082.html?tag=nefd.to
Samsung
has designed a new class of flash memory (like the memory in
your digital
camera or cell phone) that could replace the hard drives
in today's laptops
and tablet PCs:
http://news.softpedia.com/news/Samsung-is-betting-on-Flash-disk-drives-2222.shtml
As
if viruses and spyware weren't big enough problems, hackers have
now "locked"
onto a new tactic: holding your files for ransom:
http://www.techtree.com/techtree/jsp/showstory.jsp?storyid=3992
No,
this is not a remake of "Dawn of the Dead": thirty-five government
agencies
from around the world have launched an awareness campaign
aimed at pressuring
ISPs (internet service providers) to do something
about the problem of
"zombie" PCs:
http://www.cbronline.com/article_news.asp?guid=81D45DCF-E023-462C-8730-AA5088FAB972
Copy
us on the good stuff ;-)
thepcgurus@gmail.com
www.opaquelucidity.com
This week's
extension is one that lots of people will love for cleaning up the web pages
they visit every day. Adblock can be
found
here:
https://addons.mozilla.org/extensions/moreinfo.php?id=10&application=firefox
It will do
just what its title says, block ads. When you install it you
will find
a new option when you right click images to adblock them. You can go
through and do this to any and all ads that you find on the web pages that you
frequent.
Also, you will
notice adblock tabs around flash animations that adblock thinks to be ads.
If the flash is an ad, just click the tab to get rid of it as well. When
you click the tab or right click to adblock these images, you'll be taken to a
simple prompt to enter the URL for the image you want to
block. You can either take the default or you
can get rid of all ads
from that particular ad service by cutting off the
filename (which will
be after the final forward slash), and replacing it
with a *. So, if
you want to block all ads from adservice.com, instead
of letting the box
read http://www.adservice.com/ad.gif make
it read:
http://www.adservice.com/*
You'll have to do some training with this one, but in no time you'll be
free of ads from anywhere on the Internet.
Happy
Browsing!
Daniel A. Williams
daniel@thepcgurus.com
Like last week’s download, this week we feature a new version of an existing tool, this time the Netcraft Toolbar.
The anti-phishing tool, which displays information on the host of each website you visit, is now available for Firefox. You can get it for free at http://toolbar.netcraft.com/install/.
The PC Guru website is currently in the early phase of a redesign by master webmaster Ed Engelking. During the next few weeks some areas may become inaccessible. If you visit the site for the chatroom or any other feature and that feature shows unavailable please try back later.
Chatters can still access the room through an IRC client. If you need help setting one up just drop us an email…
Q: Does the Windows XP firewall provide as
good a level of protection as
the commercial firewalls
do?
A: The Windows XP firewall provides decent
protection against inbound
traffic. However, it does not monitor any
outbound traffic from your
computer such as those generated by malware
installed on your computer.
Most commercial firewalls provide both
inbound and outbound traffic
firewalls; have tracking, alerting and
customization features, and
various other bells and
whistles.
Hash
hash@ucanweb.com
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