Although most people use PDAs as electronic schedulers and notebooks, you can also use them as portable technical support tools. With the right utilities and accessories, you can use your PDA to analyze your wireless or wired network—and recoup some of your investment as well. PDAs aren’t cheap, but the more you can do with one, the easier it’ll be to justify the cost. I’ll describe how to choose and use a Compaq iPAQ as a network support tool. I’ll also recommend some tools and accessories that will help you do the job.
For the purposes of this Daily Drill Down, I’ll be using Compaq’s iPAQ PocketPC 3850, but that’s not to say that other PocketPC or Palm OS-based PDAs can’t do the job. Likewise, I won’t be offering an exhaustive list of every hardware/software combination you can use to turn your iPAQ into a portable network testing tool. There are so many different options that I can’t possibly cover them all, so I’ve listed some of my favorites to get you started.
Selecting the right iPAQ
As you can tell by looking at Compaq’s Web site, there are several iPAQ models to choose from. The model you select should have at least 64 MB of RAM. There are two distinct classes of iPAQ currently available: those using the strongARM processor, and the 3900 series using the new PXA250 400-MHz Intel processor. Several vendors that I spoke to are just now getting this newer model in the labs for testing, so keep in mind that some of the programs I’ll be discussing may not run on the newer processor.
Once you’ve selected an iPAQ, you’ll need to purchase some accessories. The accessories you’ll need will depend on how you’ll use your iPAQ.
At a minimum, you’ll need to purchase the Single PC Card Sleeve. The street price for this is around $125. This will let you use either PC Card-type network cards or a Compact Flash card with a CF-to-PC Card adapter. You can buy a dual PC card sleeve for the iPAQ, but at $199 it’s a little pricier than the single PC Card sleeve.
Although it’s not a requirement for any of the programs I’ll be discussing here, I suggest that you consider getting at least a 32-MB memory card for your iPAQ, and preferably a 64-MB card. This will let you quickly back up the iPAQ to a memory card, enabling a fast recovery if you need to do a hardware reset. Having a quick backup certainly beats having to reinstall and reconfigure all of your applications. I learned this lesson the hard way when I applied one of the ROM updates for my 3850. It reinitialized the memory in the machine during installation, and I lost everything on it.
Working with wireless networks
After you’ve selected your iPAQ, you’re ready to go to work. One job that a handheld computer is great for is tracking down wireless access points. MiniStumbler, little brother to the NetStumbler utility that runs on laptops and PCs, is a good tool for finding access points, the channels that are in use, and—more importantly—whether or not Wired Equivalent Policy (WEP) is in use.
NetStumbler and MiniStumbler
You can find out more about NetStumbler by reading the Daily Drill Down “Stumble across rogue wireless access points.”
Sometimes you’ll have questions that MiniStumbler can’t answer. In that case, you’ll need to move up to a protocol analyzer. There are several good products to choose from. When you’re considering analyzers that look at WIFI networks, bear in mind that you’ll be looking down at the physical layer, so you won’t need to capture packets based on a particular IP address or port number.
The two best candidates I’ve had a chance to use are AirMagnet from AirMagnet, Inc., and Sniffer PDA from the folks at Network Associates. Both are good choices to have in your wireless bag of tools. One feature that I like about Sniffer PDA is that it saves to a file format that can be used by the Sniffer Wireless product that runs on a laptop. I’ll cover both of these products in upcoming Daily Drill Downs.
Working with wired networks
You can use your iPAQ to test an old-fashioned wired network just as easily as a wireless network—you just need a few different tools. There are several different network cards and software that you can use to turn your iPAQ into a network analyzer.
Socket compact flash network card
I found a 10/100 compact flash network card from Socket Communications that was recommended by several vendors who make tools that run on the iPAQ. What I like most about this network card is its built-in RJ45 socket—you don’t need to use a dongle. The dongle is the one thing that you’ll have the most problems with on a network card, and it will probably be the first thing to fail.
This card’s connector housing has a series of built-in LEDs that give you a good indication of whether the network connection you’re plugging in to is live or not. The downside to this card is a driver issue that I found while doing research for this article. When you connect to a 10/100 hub or switch, the port you’re using will report a 100-MB connection, but the various tools I looked at only reported a 10-MB connection. From what I can see, this is a limitation in the current Socket CF card driver, and Socket Communications plans to correct it in the next release of the card.
When it comes to network software, one of the niftiest tools I found was IPer from Incentive Solutions. This little utility offers a lot of bang for the buck. IPer can tell if you have a working connection based on the information that it gathers and displays on the screen. Some of the things you can do with IPer include:
- Ping various devices on the network.
- Do a port scan to see what services/ports are available on a server that you’re trying to talk to.
- Browse the SNMP MIB of a device.
- Generate some UDP traffic on the network.
The next useful utility I found for the iPAQ is called Handalyzer. This utility picks up where IPer stops. Handalyzer includes three tests you can run:
- Discovery—The Discovery test reports what it sees in terms of link status, speed, and different types of IP traffic (IP, ARP, RIP, ICMP, and OSPF).
- Drop Test—The Drop Test lets you record what you “hear” on each network jack that you plug into: how the address of the iPAQ was determined, link speed, status, and anything else the Drop Test finds.
- Monitor—The Monitor test gives you some basic stats beyond link speed and status by showing you the number of packets sent or received, how many were dropped, and the number of errors sent or received.
Handalyzer also can make use of protocols like CDP and EDP to find out even more about your network. It can update the information it finds to a specially constructed Web page that can populate a database with everything Handalyzer finds on your network. It’s even smart enough to know how to go through a proxy server to do the tests or upload to the database server, if it needs to.
A full-fledged protocol analyzer could cost you an arm and a leg. However, you can turn your iPAQ into a protocol analyzer with CENiffer v3.1 from Epiphan Consulting. CENiffer includes considerable documentation to guide you through its many features. CENiffer allows you to apply both simple and advanced filters on packets to help you sort through the flood of data on your network. One feature I was glad to see is the ability to load a previously captured trace file and view the packets without needing a network card installed. To save time, you can capture the packets raw (without any filters applied) and then apply filters as you create them to help you find what you’re looking for.
Another interesting application I found for the iPAQ was vxUtil from Cambridge Computer Corp. Although vxUtil duplicates some of the features of other tools I’ve mentioned, it has some additional features, such as:
Working with console/serial interfaces
Not all network infrastructure problems can be resolved with an Ethernet connection. Have you ever gotten behind a rack and needed to access the console interface on a router or switch? If you don’t have room for a laptop to connect to the console port, you can do the job with your iPAQ. Most switches and routers have serial ports for local administration, and you can connect to them using the built-in serial port on the bottom of the iPAQ. You’ll need to purchase a separate syncing cable to connect to the bottom of the iPAQ.
In addition to the special syncing cable, you should have a female-to-female gender changer, a male-to-male gender changer, and a null modem adapter. You can purchase these at Radio Shack or any electronics store. This may seem a little like overkill, but with these adapters, you should be able to connect to just about any type of DB9 serial port you’ll come across. If you think you may encounter older DB25 serial ports, you may want to get a couple of DB9-DB25 converters.
The iPAQ includes a basic ASCII terminal emulation application. However, you can’t access some switches and routers using an ASCII terminal. In some cases, you may need VT100 emulation or something different. VxHpc allows you to make VT100 terminal connections via serial, TCP/IP, and infrared ports.
Grab it and go
I’ve just scratched the surface on the many different utilities that are available for the iPAQ and Pocket PC platform. I consider the tools I’ve described to be the best of what’s available. You may find some hardware and software combinations that suit your purposes better, but now you have a starting point, as well as some reasons to justify the cost of a PDA.