July 22, 2003
By Karen Kenworthy
IN THIS ISSUE
Some of the best products and services are ones you never notice. You expect your car to start, your computer to compute, and your Internet connection to connect. And when they do, without fail, for months or years at a time, it's easy to take them for granted.
Unfortunately, I haven't always been so lucky. And judging from my e-mail, neither have many of you. :(
Lots of us have experienced temporary outages of one type or another. Perhaps your connection to the Internet broke, leaving you and your computer isolated and alone. An e-mail server may have stopped serving, feeling it had delivered enough mail for one day. Or a web site suddenly decided the only page anyone wanted was one reading "The page cannot be displayed ... Cannot find server or DNS Error".
Often we know the moment a problem occurs. One minute we're happily surfing the web, the next minute we've crashed and washed ashore. Or the raging river of spam suddenly turns into a dry creek bed. In these cases we know immediately something's gone wrong.
But other times Internet problems can go undetected for hours, or even days. Are you sure your public or intranet web site is working right now? Or are visitors getting the impression you've gone out of business, or left the 'net? Was your e-mail server working all last night? Or did important e-mail get bounced or delayed?
Even when a problem is detected, it's important to find patterns and gather statistics. Does your Internet connection become flaky every afternoon at 3 p.m.? Does the "rock solid" connection you're paying for actually fail 5% of the time? How can you find out?
For all these reasons, and more, I wrote a program called the 'Net Monitor. It repeatedly tests Internet connections, web sites, and e-mail servers, making sure they are working correctly. If a failure is detected, the site being tested, the date and time of the test, and the reason for the failure, are recorded in a log.
The program can also send e-mail messages, alerting you to the problem. If the message is sent to a paging service or cell phone, the 'Net Monitor can even wake you up in the middle of the night, making sure you sleep soundly the next afternoon. :)
The original 'Net Monitor has been one of the most popular of my Power Tools. But I've made several improvements recently, which make the program even more useful.
One new feature might let you sleep, or save a weekend trip to the office. The program now lets you specify two e-mail messages for each site being monitored. One is sent when a site fails, as before. But the other is sent when the site begins operating properly again. This lets you distinguish short intermittent problems, and a long outage.
The new 'Net Monitor also makes it easier to perform tests "on demand." It has always performed tests automatically, at an interval you choose. For example, you can ask the program to test each site every five minutes. And the program has long allowed you to initiate a full battery of tests, checking every site in its list, by clicking its "Test All" button.
Now it sports a new button, "Test Selected Now", which instantly tests a single web site or e-mail server. This is handy when trouble-shooting, letting you know immediately if a change has solved a problem, or made it worse. :)
Another 'Net Monitor enhancement was inspired by reader Alexander Blood. He recently sent a copy of my own program's source code, with additions that allow the 'Net Monitor to access web sites via "Proxies."
What is a Proxy? In human terms, it's someone who acts on another's behalf. Do you own stock in a large company? Then you've probably been asked to sign a proxy statement -- a legal document giving someone else the authority to cast your vote at the next stockholders meeting.
But a proxy can do a lot more. You can choose a proxy who'll negotiate and sign your next employment contract. Or buy things for you at a store. Almost any job you can't, or would rather not, do can be performed by a proxy.
Hard-working computers know a good idea when they see one. That's why they use proxies too. Is your computer connected to a local area network (LAN)? If so, ask your computer to read data from another network computer's drive, or print on a network printer. Your computer will pass your request to a proxy. It asks a remote computer, the one directly connected to the network device, to actually read the disk or print the report. The proxy does the job, then tells your computer when a job has been finished successfully, or when an error occurs.
Network disks and printers are important, but dull. But another computer proxy is mysterious, glamorous, and exciting: Your computer can use a proxy to secretly access the Internet.
When your computer sends e-mail, or visits a web site, it sends short messages to the distant computer, specifying the e-mail's recipient and text, or identifying web page we'd like to view. These messages also contain a "return address" -- information that allows the remote computer to reply, sending information back to your computer.
That's right. While accessing other computers over the Internet, you're transmitting information that identifies your computer. This information reveals that your computer exists, is connected to the Internet, and provides everything needed to directly access your computer. <gulp>
Fortunately, this isn't the end of the world. You've been transmitting your computer's address for as long as you've been using the Internet. And for most folks, this hasn't caused any harm. Most computers aren't very interesting, not enticing targets for hackers or other ne'er-do-wells. And many of us protect our computers from unwanted communication, using "firewalls", and configuring Windows to ignore most incoming messages.
But for added security, some careful folks connect to the Internet anonymously. For that, you need a spare computer, and a special program called a "proxy".
To use this sort of proxy, first disconnect your computer from the Internet. No modem that dials your ISP. No network card that sends information to a router or other 'net "gateway."
Next, connect your proxy computer to the Internet. Make sure your computer can communicate with the proxy, and with other computers connected to your local network.
Finally, reconfigure your 'net software. From now on, your web browser, e- mail program, and all other programs must only talk to the proxy.
That's it. Want to see a web page? Your web browser asks the proxy for the information. The helpful proxy contacts the remote web server, discretely acting on your behalf. When the reply arrives, the proxy forwards the web page to your computer, which miraculously appears on your screen!
Your computer remains hidden, because the proxy computer's return address is sent over the 'net, not yours. Best of all, because it no long has its own connection to the Internet, your computer is inaccessible, out of the reach of 'net hooligans.
Obviously, Internet proxies are a great idea. But older versions of my 'Net Monitor program required a direct connection to the Internet or server being tested. Fortunately, the latest version can use a proxy instead. All it needs is the proxy computer's name, and your login name and password (if the proxy requires one).
The new 'Net Monitor has another feature needed by folks running some secure e-mail servers: You can now specify the "port" used when connecting to the server. This allows you to test e-mail servers configured in a non- standard way, perhaps to make them harder targets for hackers, or to allow more than one e-mail server to run on a single computer.
Tip: The monitor has always been able to test web servers that use non- standard ports. Just add the port number after the domain name, when entering the URL to be tested. For example, to test the page /default.asp, at a web server named www.microsoft.com, that responds to port 8080, use a URL like this:
E-Mailer II Update
The 'Net Monitor isn't the only Power Tool getting a makeover recently. I've also updated the 'Net Monitor's loyal companion, E-Mailer II.
As its name suggests, the E-Mailer sends e-mail. The 'Net Monitor asks it to notify us when a server fails. It turns to the mailer again, to announce the restoration of service. The Countdown Timer II program also uses the E-Mailer, when sending an e-mail message alerting you to an event. You could say the E-Mailer is a proxy, sending e-mail on behalf of other Power Tool programs. :)
The E-Mailer II has long let us define several recipients for each message. Some of them can be "primary" recipients, shown in an e-mail message's "To" list. Others can be "carbon copy", or CC, recipients. They also appear in a message, on a line prefixed with the letters "CC".
But now, the E-Mailer can send messages to folks without their addresses appearing in the message. These special folks are called "blind carbon copy" (BCC) recipients. Their identity, and the fact that they are even receiving a copy of the e-mail message, is kept secret from the message's "To" and "CC" addressees.
Another recent change allows the E-Mailer II to work with the popular Eudora e-mail client. Previously, the E-Mailer offered two options when sending a message: Contact your e-mail server directly (called the SMTP, or Simple Mail Transport Protocol, method), or ask your e-mail program to do the job.
Before an e-mail program can be used by the E-Mailer, it must support a standard known as MAPI (Mail Application Program Interface). E-Mail programs such as Microsoft's Outlook fully support this standard, as do many other popular programs.
Unfortunately, Eudora only supports a portion of the full MAPI standard. In the past, this prevented the E-Mailer II from using Eudora to send e- mail messages.
But the new E-Mailer offers a new MAPI option, called the "Alternate MAPI Library". This choice allows Eudora, and other e-mail programs that support limited portions of the MAPI standard, to work with the E-Mailer II!
If you'd like to try the new versions of the 'Net Monitor and E-Mailer II, drop by their home pages at:
As always, both programs are free (for personal use). And those interested in what's "under the hood" can download the programs' free Visual Basic source code too!
Or if you prefer, get the latest version of every Power Tool, including the new 'Net Monitor and E-Mailer II, on CD. The disc also includes three bonus Power Tools, not available anywhere else. You'll find every back issue of my newsletter, and a few articles, in the CD's library. The CD even includes a special license that lets you use your Power Tools at work.
Best of all, buying a CD is the easiest way to support the web site and this newsletter. To find out more about the CD, visit:
Until we meet again, may your TCP/IP packets always be delivered. May your IP datagrams never expire. And if you see me around the secluded Power Tools workshop, or on the 'net, be sure to wave and say "Hi!"
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