Brush Valley Brewer

The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets:

• 10.0.0.0 – 10.255.255.255 (10/8 prefix)
• 172.16.0.0 – 172.31.255.255 (172.16/12 prefix)
• 192.168.0.0 – 192.168.255.255 (192.168/16 prefix)

We will refer to the first block as ‘24-bit block’, the second as ‘20-bit block’, and to the third as ‘16-bit’ block. Note that (in pre-CIDR notation) the first block is nothing but a single class A network number, while the second block is a set of 16 contiguous class B network numbers, and third block is a set of 256 contiguous class C network numbers.

Y. Rekhter, B. Moskowitz, D. Karrenberg, G. J. de Groot, and E. Lear (1996, February), Address Allocation for Private Internets. Retrieved Monday, September 15, 2003, from www.apps.ietf.org/ rfc/ rfc1918.html.

To participate in wide-area IP networking, a host needs to be configured, either manually by the user or automatically from a source on the network such as a DHCP server. Unfortunately, such external configuration information may not always be available. It is therefore beneficial for a host to be able to depend on a useful subset of IP network to always be functional, even when no configuration information is available. This document describes how a host may automatically configure an interface with an IPv4 address within the 169.254/16 prefix that is valid for communication with other devices connected to the same physical (or logical) link. Communication using Link-Local IPv4 addresses is not suitable for communication with devices not directly connected to the same physical (or logical) link.

Stuart Cheshire, Bernard Aboba, and Erik Guttman (2003, June 3), Dynamic Configuration of Link-Local IPv4 Addresses. Retrieved Septembet 8, 2003, from files.zeroconf.org/ draft-ietf-zeroconf-ipv4-linklocal.txt.

The <a href="http://www.washingtonpost.com/wp-dyn/technology/columns/webwatch" title="TechNews.com: Web Watch">Web Watch</a> column over at the <a href="http://www.washingtonpost.com/" title="washingtonpost.com - nation, world, technology and Washington area news and headlines">Washington Post</a> has an <a title="Google Searches the Web And Does Math Homework (TechNews.com)" href="http://www.washingtonpost.com/wp-dyn/articles/A1833-2003Aug16.html">interesting article</a> about a new feature in the <a href="http://www.google.com/" title="Google">Google</a> search engine. Here is a &#8220;link annotated&#8221; quote from the article.

The Internet’s top search engine announced it had crammed a mathematical calculator into its search service, letting users type math problems directly into the search box and get instant answers. Google’s calculator is trained to recognize words as well as numbers, so you can type in “eight plus seven minus four” or “8 plus 7 minus 4.” Both will yield 11.

You can type numeric expressions either into the search box at Google’s Web site (www.google.com) or directly into your Internet browser if you’ve installed Google’s tool-bar software or you use a browser with built-in Google searching, such as Mozilla or Apple’s Safari. Below the numeric answers Google returns, it will present a link to a regular Web search for your phrase in case you weren’t trying to use the calculator.

But this calculator doesn’t just do simple multiplication. It also handles conversions. Cooks may like being able to type in “quarter cup in teaspoons” and see Google reply “1 quarter US cup = 12 US teaspoons.” Does a mechanic want to know the size of a replacement part for a clock in inches, but you only know it in millimeters? Enter “.715 mm in inches” and Google will inform you it equals 0.0281496063 inches.

Google’s calculator goes beyond basic arithmetic to do complex math and crunch physical constants, too. It will process such queries as “G * mass of earth.” or “speed of light * two.” Type “What is the speed of light in furlongs per fortnight” and you’ll get this reply: “the speed of light = 1.8026175 x 10¹² furlongs per fortnight.”

Leslie Walker (2003, August 17), <i>Google Searches the Web And Does Math Homework</i>. Retrieved Sunday, September 14, 2003, from <a href="http://www.washingtonpost.com/wp-dyn/articles/A1833-2003Aug16.html" title="Google Searches the Web And Does Math Homework">www.washingtonpost.com/ wp-dyn/ articles/ A1833-2003Aug16.html</a>.

One of the keys to any type of security is knowledge. To keep a network secure, you must know about security in general, but you must also be aware of the environment in which your computers operate.

For example, any computer that’s connected directly to the Internet is likely to see several unauthorized access attempts per day from outside the local network. Indeed, there may even be suspicious activity from within your local network, either from disgruntled insiders or from a successful outside intrusion or infection. If you’re to effectively guard against intrusions, it’s helpful to be aware of them. Even if you don’t respond to every probe (a monumental and unrewarding task), changes in the patterns of attack may be important: Changes may tip you off to new vulnerabilities and attack tools.

Network monitoring tools help you keep an eye on network attacks… Snort is a very powerful system for monitoring network traffic.

Roderick W. Smith (2003, May), <i>Network Monitoring with Snort</i>. Retrieved Sunday, September 14, 2003, from <a href="http://www.linux-mag.com/2003-05/guru_01.html" title="Linux Magazine | May 2003 | GURU GUIDANCE | Network Monitoring with Snort">www.linux-mag.com/ 2003-05/ guru_01.html</a>.

<a href="http://www.stonehenge.com/merlyn/" title="Randal L. Schwartz">Randal L. Schwartz</a> (a.k.a. <a href="mailto:merlyn@stonehenge.com" title="Send email to merlyn@stonehenge.com">merlyn</a>) is the &ldquo;chief Perl guru at <a href="http://www.stonehenge.com/" title="Stonehenge Consulting Services, Inc.">Stonehenge Consulting</a>.&rdquo; He has a <a href="http://www.linux-mag.com/depts/perl.html" title="Linux Magazine | DEPARTMENTS | PERL OF WISDOM">regular column</a> over at <a href="http://www.linux-mag.com/" title="Linux Magazine: Open Source. Open Standards.">Linux Magazine</a>. He has also helped write a number of books on the Perl programming language, including:

• Learning Perl, 3rd Edition
• Learning Perl Objects, References, and Modules
• Learning Perl on Win32 Systems
• Effective Perl Programming: Writing Better Programs With Perl
• Object Oriented Perl

Moments before a top Microsoft executive told Congress about efforts to improve security, the company warned on Wednesday of new flaws that leave its flagship Windows software vulnerable to Internet attacks similar to the Blaster virus that infected hundreds of millions of computers last month.

The Associated Press (2003, September 11), <i>Microsoft Admits New Windows Problem</i>. Retrieved September 11, 2003, from <a href="http://nytimes.com/aponline/technology/AP-Microsoft-Security.html" title="Microsoft Admits New Windows Problem">nytimes.com/ aponline/ technology/ AP-Microsoft-Security.html</a>.