Wireless Networking with OS/2 and eCS FAQ

By Jonas Buys

1. Technology
'Can I run an application from a remote computer over the wireless network? 'This will depend on whether or not the application is designed to be used over a network. In general, if the application is designed to work with wired networks, it will also run over wireless local area networks, since wireless local area networks are just the same as wired ones, only the data is being transported differently. The computer does not need to know how data is transported; it only needs to know that data is effectively transferred. Thus, the Lotus Domino, Lotus Notes, and IBM WebSphere concepts shouldn't cause problems using WiFi.

'Can I play computer games with other members of the wireless network? 'Yes, as long as the game supports multiple players over a local area network.

'If my computer is connected to a wireless LAN, can it communicate with computers on a wired LAN as well? 'This was already described in the introduction article. Consider this information as an addition to the information provided in the article. To do this you will need some sort of bridge between the wireless and wired network. This can be accomplished either via a hardware access point or a software access point. Hardware access points are available with various types of network interfaces, such as Ethernet or Token Ring, but typically require extra hardware (mostly a Wireless Access Point, WAP) to be purchased if your networking requirements change. If networking requirements go beyond just interconnecting a wired network network to a small wireless network, a software access point may be the best solution. A software access point does not limit the type or number of network interfaces you use. It may also allow considerable flexibility in providing access to different network types, such as different types of Ethernet, Wireless and Token Ring networks. Such connections are only limited by the number of slots or interfaces in the computer used for this task. Further to this the software access point may include significant additional features such as shared Internet access, web caching or content filtering, providing significant benefits to users and administrators.

'What is BSS ID? And ESS ID? 'A specific adhoc local area network is called a Basic Service Set (BSS). Computers in a BSS must be configured with the same BSS ID. An infrastructure configuration could also support roaming capability for mobile workers. More than one BSS can be configured as an Extended Service Set (ESS). Users within an ESS could Roam freely between BBSes, while served as a continuous connection with the same ESS ID and the same radio channel.

'What is Spread Spectrum? 'Spread Spectrum technology is a wideband radio frequency technique developed by the military for use in reliable, secure, mission-critical communications systems. It is designed to trade off bandwidth efficiency for reliability, integrity, and security. In other words, more bandwidth is consumed than in the case of narrowband transmission, but the trade off produces a signal that is, in effect, louder and thus easier to detect, provided that the receiver knows the parameters of the spread-spectrum signal being broadcast. If receiver is not turned to the right frequency, a spread-spectrum signal looks like background noise. There are two main alternatives, DSSS and FHSS.

'What is DSSS? What is FHSS? And what are their differences? 'A spectrum is a range of frequencies and these are split into bands, and then into channels. FHSS, Frequency Hopping Spread-Spectrum uses a narrowband carrier that changes frequency in a pattern that is known to both transmitter and receiver. Properly synchronized, the net effect is to maintain a single logical channel. To an unintended receiver, FHSS appears to be short-duration impulse noise. DSSS, Direct-Sequence Spread-Spectrum generates a redundant bit pattern for each bit to be transmitted. This bit pattern is called a chip (or chipping code). The longer the chip, the greater the probability that the original data can be recovered. Even if one or more bits in the chip are damages during the transmission, statistical techniques embedded in the radio can recover the original data without the need for retransmission. To an unintended receiver DSSS appears as low power wideband noise and is rejected (ignored) by most narrowband receivers.

'Would the information be intercepted while transmitting on air? 'Wireless local area network features two-fold protection in security. On the hardware side, as with DSSS technology, it has the inherent security feature of scrambling. On the software side, wireless local area network series offer the WEP encryption to enhance security and Access Control.

'What is wireless networking? ' The term wireless networking refers to technology that enables two or more computers to communicate using standard network protocols, but without network cabling. Strictly speaking, any technology that does this could be called wireless networking. The current buzzword however generally refers to wireless LANs. This technology, fueled by the emergence of cross-vendor industry standards such as IEEE 802.11, has produced a number of affordable wireless solutions that are growing in popularity with business and schools as well as sophisticated applications where network wiring is impossible, such as in warehousing or point-of-sale handheld equipment.

'What is a WLAN card's range? 'Each access point has a finite range within which a wireless connection can be maintained between the client computer and the access point. The actual distance varies depending upon the environment; manufacturers typically state both indoor and outdoor ranges to give a reasonable indication of reliable performance. Also it should be noted that when operating at the limits of range the performance may drop, as the quality of connection deteriorates and the system compensates. Typical indoor ranges are 150-300 feet, but can be shorter if the building construction interferes with radio transmissions. Longer ranges are possible, but performance will degrade with distance. Outdoor ranges are quoted up to 1000 feet, but again this depends upon the environment. There are ways to extend the basic operating range of Wireless communications, by using more than a single access point or using a wireless relay /extension point. See Question 8 for further information.

'Can I mix wireless equipment from different vendors? ' Because most wireless networking hardware vendors support the 802.11b standard they can inter-operate. However, Frequency Hopping (FH) and Direct Sequence Spread Spectrum (DSSS or DS), are not inter-operatable. When purchasing wireless networking hardware from separate vendors be sure to obtain guarantees from the vendors that the hardware will interoperate and follows the standards. Also of note is that the latest version of the standard defines 11mbps and 5.5mbps networking, with support for the older standard 1mbps and 2mbps speeds. This provides some compatibility with different or older equipment. Note that this new standard covers DSSS-type Networks, not FHSS types. Software access points which uses the wireless interface of the host computer should have no compatibility issues with third party wireless hardware, as long as standards are followed. Typically wireless hardware is identified to the software as a network interface, and therefore can be used in the same way as any other network card.

How is the 802.11a's security different than 802.11b? Most manufacturers of wireless technologies have come out with 802.11a technology now. The specifications for the protocols of 802.11a are very similar to 802.11b, therefore many of the security risks are shared for both 802.11a and 802.11b. Many of the security issues around 802.11b will continue to be an issue with 802.11a, therefore by understanding current issues will help organizations deal with future issues as well.

What is an Access Point? The AP (access point also known as a base station) is the wireless server that connects clients to the internal network. Base stations typically act as a bridge for the clients. There is an IP address for management configuration of the base station.

'How much does the equipment for wireless 802.11b cost?' Base stations have become relatively inexpensive, approximately under USD 300. The 802.11 client cards for PDAs, laptops, and desktops are approximately under USD 100. Because of inexpensive equipment to get into wireless, attackers can get easy access to the tools necessary to apply the attack. Because of the inexpensive price, within many companies employees can purchase wireless equipment without approval and deploy this in a rogue fashion, creating additional risk. However, wireless products tend to be a lot more expensive that regular wired solutions.

'How does the external antenna affect wireless LAN security?' Because the intruder must be within range of the signal, a properly selected and positioned antenna within a building can minimize how far the signal can reach and therefore reduce leakage and interception. Remind that an external antenna normally increases the range and thus augments the insecurity of wireless technology.

2. OS/2 Drivers
'Do I need to reboot every time I change my WLAN card's configuration?' No, surely not! When installing the driver using MPTS, edit the basic setting in the *.NIF file, and then after a reboot, use the WiFiStat.exe utility. More information about this little tool can be found here.

' Where can I get the drivers for wireless devices compatible with OS/2 and eCS? 'For the Artem, BinTek and SteinKeuhler products, there is a free driver available from the manufacturer, and they are also shipped out of the box. However, for other drivers you can find all the information at [].