Goodies to Go ™
August 25, 2003–Newsletter #247
This newsletter is part of the internet.com network.
http://www.internet.com
Featured this week:
* Goodies Thoughts – Static v
Dynamic
* Q & A Goodies
* News Goodies
* Goodies Peer Reviews
* Feedback Goodies
* And Remember This…
Goodies Announcement
Just in case you missed
it before, the new Beyond HTML Goodies book is now available!
Go beyond the basics
and learn how the pros add and use dynamic HTML features and advanced
JavaScript techniques. Beyond HTML Goodies demonstrates dozens of new and
different features readers can add to their existing Web pages using HTML and
JavaScript. The book starts with simple text and image tips, such as adding a
clock to a Web page or causing text to appear when the mouse moves over an
image. It gradually builds to more complex tricks, including manipulating forms
or working with cookies behind the scenes. Throughout the book, readers enjoy
Joe’s snappy style and “to the point” discussion of each “goody” in the book.
http://books.internet.com/books/0789727803
Goodies Thoughts – Static v Dynamic
"Oh no contest! Dynamic wins, hands down!" I hear from the peanut gallery.
"Really?" I reply, "and it doesn’t matter what we’re talking about?"
The great thing about Goodies to Go readers is that they don’t fall for trick
questions like that! Of course, had the topic been web site content, then our
peanut gallerian might have been on the right track. But if the topic was those
pesky, ever changing IP numbers that our service providers assign to us, we
could be singing a different song entirely. It’s actually the problems of
Dynamic IP address assignment that I’ll be singing about today. Luckily for you,
you’re reading this and so can’t hear me "sing" — another huge benefit of the
Internet!
Maybe you’re building a new website and something isn’t going quite right so you
want your friend to take a look at it and see if they can help you out. Or,
perhaps you’ve got a neat liitle game server going and you’d like your fellow
gamers to be able to get into it. Then again, maybe you just want to be able to
use some remote access mechanism to get to stuff in your own PC from the
Internet. In each of these scenarios, and many more like them, the problem is
that you have to know where your machine is. That is, you have to know its
address. How can you know it’s address when your service provider can change it
on you at their whim? DDNS, that’s how.
Dynamic Domain Name System/Service (DDNS) provides a means to translate a name
into the address of your computer and to keep track of it as the address
changes. The purpose of the Domain Name System is to resolve, or translate, a
name like www.HTMLGoodies.com into an
IP address. Names are much easier to remember than numbers and to most of us
they are also more meaningful.
Usually, records are entered into a DNS server computer to indicate the address
associated with a name within a domain. For example, when the domain name
htmlgoodies.com was registered it was set to point to the Domain Name Server
ns1.internet.com (as a primary DNS server.) A record in that server points the
name "www" (a "hostname") to the IP address of the web server that houses our
website. When you type www.htmlgoodies.com
into your browser and hit "go" or "enter", your browser uses the DNS service to
obtain the IP address of that server and sends it a request for our home page.
The DNS specifications now include the ability to dynamically add or change
these records. All you need is a piece of software that can monitor your IP
address and send it to a service that will accept the dynamic update. Where can
you get these and how much will it cost you? I knew you’d ask! There a a few
answers; here are a couple of the most popular.
Dynamic DNS Network Services, LLC, aka DynDNS.org, provides a free service as
well as a premium service. The free service enable you to include up to five
(currently) hostnames in one of their forty-three (currently) domain names. They
provide links to client software (the part that will run on your computer) for
you to obtain a free client for any of the common platforms/operating systems.
Their premium service allows you to use your own domain name, and to record more
host names. Their service works well even if your computer is behind a router.
Some routers in fact also support DDNS themselves. Netgear, Linksys and several
other vendors incorporate this support into some models of their routers. Check
with the manufacturer’s website before you buy if this is important to you.
Another company offering DDNS service is Tzolkin Corporation aka tzo.com Their
services start at about US$24.95/year. Tzolkin doesn’d use BIND. BIND is the
most common software used for DNS and Tzolkin argues that this makes it a
frequent target of hackers. By not using BIND they keep themselves away from
these attacks.
Both companies have redundancy/back-up servers in at least three different
locations. One of Dyndns.org’s servers is located in Europe. As of this writing,
Tzolkin boasts five locations across the US. You will have to decide for
yourself what you think is important.
Both companies also offer a solution for that other little annoyance coming from
so many service providers. Namely, port 80 blocking. Requests for web pages come
in on TCP/IP Port 80. By blocking inbound port 80 requests the ISP intends to
prevent you from running a web server behind their connection. While this may
work for the average citizen, it is only a minor impediment for a Goodies to Go
reader. They simply log into their DDNS provider’s site and set up Port
Redirection (as Dyndns.org calls it) or HTTP Relay (as Tzolkin calls it). This
way, unknown to the surfer visiting the site, the incoming Port 80 request is
forwarded to a different port on your computer (a port which your service
provider doesn’t block) whose IP address is well known to the DDNS service.
If your computer is behind a router with a built in Firewall, or if you run
Firewall software, don’t forget to make sure that the inbound port you choose is
open there too. And, of course, since your machine is to be providing services
to the Web, make sure that you keep your security up to date (see last week’s
Goodies to Go at
https://www.htmlgoodies.com/letters)
Thanks for Reading!
– Vince Barnes
Q & A Goodies
Questions are taken from submissions to our Community Mentors. You can ask a Mentor a question by going to
https://www.htmlgoodies.com/mentors.
Q. Is is possible to place a cell that provides scrolling capabilities
into a specific location within a table? I have information that I wish to place
in the cell, but do not want to enlarge the height of the page.
A. What you are looking for is an inline frame. The problem that you will
to look out for is that inline frames are only recognized by Internet Explorer
4.0 and above and I think Netscape 6 and above. Here is a tutorial on inline
frames:
https://www.htmlgoodies.com/tutors/inlineframes.html
Q. I am having trouble with using named parameters in JavaScript code.
For example, in this simple mathematical code:
var number : integer = cos (30);
document.write (" the Cosine of 30 Degrees is " + number + " ")
This is where I’m trying to calculate the cosine of 30 degrees and have made a
rule that the "number" variable must always be an integer. However, when I
attempt to run this code, I get the error message in Netscape: [missing ";"
before statement] in the line of code "var number : integer = cos(30)". I always
get this type of message whenever I try to set any variable to always be an
integer or string. What am I doing wrong?
A. Unlike other languages you cannot specify if a variable is a string or
integer in JavaScript. Here is an example of how it would be done.
<hmtl>
<head>
<title>Test</title>
</head>
<body>
<script language="javascript">
var number = Math.cos(30);
document.write (" the Cosine of 30 Degrees is " + number + " ");
</script></body></html>
And here is link to a tutorial on the Math object:
http://www.javascriptkit.com/javatutors/math.shtml
Q. This code is supposed to display the date like this, Friday 1st August
2003, but instead of showing 1st, 2nd and 3rd, it displays 1th, 2th, 3th. I’ve
tried everything I can think of to fix the problem. What do you think?
<SCRIPT>
newdate = new Date()
var wday = newdate.getDay()
var day = newdate.getDate()
var month = newdate.getMonth()
var year = newdate.getYear()
if (day == 1)
{ var dayex = "st" }
if (day == 2)
{ var dayex = "nd" }
if (day == 3)
{ var dayex = "rd" }
else
{ var dayex = "th" }
// End of day extension
if (month == 0)
{ var month = "January" }
if (month == 1)
{ var month = "Febuary" }
// above code repeats for month indexes 2-11
// End of months
if (wday == 0)
{ var wdayex = "Sunday" }
if (wday == 1)
{ var wdayex = "Monday" }
// above code repeats for day of week indexes 2-6
// End of week day
document.write(wdayex + " " + day + dayex + " " + month + " " + year)
</SCRIPT>
A. I would recommend that you leave it off. You would have to either use
either a series of if statements to check each day of the month or do some
string manipulation to check the last digit of the day variable to determine
which extension to use. As your code is currently written you will always
default to "th" if the day variable is anything other than "3". That is because
this if statement:
if (day == 3)
{ var dayex = "rd" }
else
{ var dayex = "th" }
says that if the day is not 3 then it sets the dayex variable to "th",
overriding your previous if statements.
[You could also initialize it to "th" then change it to "st", "nd" or "rd" for
values of 1, 21, 31, 2, 22, 3 or 23 – Ed.]
Q. I have a question about backgrounds and style sheets. Is there any way
(such as using the "repeat-y" function) to get the background to border down the
right as opposed to the left side? Also, is there a way to get it to tile down
both sides? I am essentially interested in getting the look of a border on both
the left and right side of the page, but i want it to appear correctly on all
screen resolutions, so of course, making a very long image with the desired left
and right backgrounds simply on opposite sides or the image would be
impractical.
A. I have one way for this to work; however, it doesn’t work in IE 5.5 (I
don’t currently have access to IE 6 at the moment, but can check later). It does
work in NN 6 and above, Mozilla, and Opera.
Add two divs to the bottom of your HTML file:
<div id="left"></div>
<div id="right"></div>
Then add the following CSS:
#left {
position: fixed;
top: 0;
left: 0;
width: 100px;
height: 100%;
border: 1px solid red;
margin: 0;
padding: 0;
background: url(ava.gif) repeat-y top left fixed; }
#right {
position: fixed;
top: 0;
right: 0;
width: 100px;
height: 100%;
border: 1px solid red;
margin: 0;
padding: 0;
background: url(ava.gif) repeat-y top right fixed; }
This will set backgrounds for the two extra divs in your HTML, and should tile
the length of the page. IE 5.5 doesn’t recognize the "fixed" property for
anything other than background images for the BODY tag, so the extra divs scroll
with the page.
News Goodies
Security Specialists Respond in Force
[August 25, 2003] Security software companies Symantec and Network
Associates position themselves as the defender against worms and
viruses.
Click
here to read the article
‘Critical’ Security Hole in Real’s Helix Server
[August 25, 2003] Workarounds are recommended for the root exploit
vulnerability which carries a ‘highly critical’ rating.
Click here to read the article
DMA Plans Spam Sting
[August 25, 2003] The direct marketing group plans to link up with the FBI
to hunt down spammers breaking the law.
Click here to read the article
Macromedia Retools MX Line
[August 25, 2003] The Web design software and developer tool maker
announces new MX 2004 applications, touts new look and feel and tighter
integration.
Click here to read the article
Switchboard Rolls Out Paid Link Program
[August 25, 2003] Advertisers can buy links on their local listings or on
another non-commercial listing.
Click here to read the article
Level 3, SBC Extend Dial-Up Deal
[August 25, 2003] The backbone network operator Level 3 will carry Internet
traffic from the service provider through 2006.
Click here to read the article
Sobig.F Weekend Attack Thwarted; Feds Hunt Source
[August 25, 2003] Despite claiming a minor victory over a second wave of the
fast-spreading worm, experts warn that open ports on infected machines
continue to pose a major threat.
Click here to read the article
Ask Jeeves Adds Search Tools
[August 25, 2003] Smart Answers give searchers weather
forecasts, airline flight delays and metric conversions.
Click here to read the article
Utility Computing Shines in Blackout
[August 22, 2003] Experts say the ability to provision computing resources
from remote locations keeps businesses running during a blackout, even when
their own data centers are without power.
Click
here to read the article
Intel Chips Start Flying Off the Shelves
[August 22, 2003] Great demand for the company’s microprocessors,
chipsets and motherboards seem to support analysts’ predictions of a PC
revival in the next 12 months.
Click here to read the article
Every week a site selected each week for review. Each week,
reviews of the previous week’s selected site are chosen for
publication on the HTML Goodies website.
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Did you ever wish your newsletter was an easy two way communications medium?
Ploof! It now is!
If you would like to comment on the newsletter or expand/improve on something
you have seen in here, you can now send your input to:
mailto:nlfeedback@htmlgoodies.com
We already receive a lot of email every day. This address will help us sort out
those relating specifically to this newsletter from all the rest. When you send
email to this address it may wind up being included in this section of the
newsletter, to be shared with your fellow readers.
Please don’t send your questions to this address.
They should be sent to our mentors: see
https://www.htmlgoodies.com/mentors/
Gilbert Leighton wanted to point out that I didn’t mention
firewalls in my piece about worms last week. That’s true,
Gilbert, and thank you. I agree that firewalls a good form
of protection. Whether they are in the form of a device that
sits between your computer and the device that connect you
to the Internet (e.g. your cable or DSL adapter) or the
software kind that runs in your computer, like the one
that’s built in to Windows XP, all firewalls are a very
helpful weapon in the battle to defend our PCs. Make no
mistake though Gilbert! They are NOT foolproof! You still
need to take care of other forms of defense. I have said it
before and will often repeat it; computer system security is
a journey, not a destination. Your very best defense starts
with concerted vigilance.
Thanks again for all your feedback!
Windows Tech Goodie of the Week:
ASP.NET Calendar Sample
One of the more tedious things to design and build in
classic ASP is now so easy it’s scary. Here’s a quick
introduction to using the ASP.NET calendar control.
http://www.asp101.com/samples/calendar_aspx.asp
** and **
Creating a Generic Pager Control
ASP.NET provides only one control that supports paging, the
DataGrid. Tomasz Kaszuba shows how to build and implement a
custom pager for different controls that change depending on
the data source or presentation.
http://www.15seconds.com/issue/030812.htm
Top
And Remember This . . .
On this day in…
1944 Paris Liberated
The French 2nd Armored Division and the U.S. 4th Infantry
Division swept the Nazis out of Paris on this morning in
1944. The Nazis had taken Paris on June 14, 1940. The French
2nd Armored Division, which had been formed in London the
year before especially for the purpose of liberating Paris,
was under the command of General Jacques-Philippe Leclerc
and was attached to General George S. Patton’s 3rd U.S.
Army. On the 23rd, the 2nd Armored Division advanced on
Paris from the north and the 4th Infantry Division from the
south. By midnight the 2nd Armored was at the Httel de Ville
in the heart of Paris. In the morning, the 2nd Armored
cleared the western half of the city and the 4th Infantry
cleared the east. German General Dietrich von Choltitz was
arrested by the French in his headquarters. Although he had
set explosives all over the city, in the end he deliberately
disobeyed Hitler’s direct order to leave Paris as a "field
of ruins". He did not want to be remembered as the man who
destroyed Europe’s "City of Light".
Today was also the day that: in 1718 French colonists
arrive in Louisiana to found New Orleans; 1814 the
British capture Washington DC; 1830 Belgiun revolts
against the Nertherlands; 1875 Matthew Webb is the
first to swim the English Channel; 1900 philosopher
Freidrich Nietzsche died in Weimar, Germany; 1921 US
signed peace treaty with Germany; 1981 M- C-
sentenced to 20 years for murder of John Lennon; 1990
UN Security Council authorizes military action against Iraq
Born today were: in 1530 Ivan Vasiljevich (Ivan IV,
Ivan the Terrible, Grand Prince "all over the Rus"); 1819
detective agency founder Allan Pinkerton; 1918
conuctor/composer Leonard Bernstein; 1918 actor
Richard Greene (Robin Hood); 1919 Ala. Gov. George
Wallace; 1923 game show host Monty Hall; 1930
actor Sean Connery; 1931 TV personality Regis Philbin;
1933 actor Tom Skerritt; 1947 actress Anne
Archer; 1954 rock musician Elvis Costello; 1970
super-model Claudia Schiffer
Thanks for reading Goodies to Go!
