mukesh agrawal

Various notes on technical matters

Windows 2000 and Networking

Installing Service Pack 2 on my Windows 2000 installation broke TCP. TCP packets simply never made it out of the Windows networking stack. Very peculiar, as UDP and ICMP packets had no trouble. Solution: uninstall SP2.

USRobotics Wireless PC Card

The USR Wireless PC Card 2410 works with Linux. It is based on the Intersil Prism II chipset, which is more hacker friendly than the chipset in the Lucent cards. For example, with the appropriate driver, cards based on the Prism II chipset can reportedly be used for bridging. The Lucent cards can not (at least not with the stock card firmware).

There are three drivers for using this card with Linux:

Orinoco driver

This driver worked right away without any trouble. It also plays nicely with the Linux wireless tools (iwconfig and iwpriv). The down side is that it does not support monitor mode. Monitor mode is needed for capturing raw 802.11 frames. Raw frames are useful for network scanning and debugging.

linux-wlan-ng driver

As shipped, the USR card had an early firmware version (the Orinoco driver reported the version to be less than 0.08) which seemed not to work with this driver. With the early firmware, the system would receive packets without trouble, but failed to send packets. After updating to more recent firmware, the card works fine with this driver.

The advantage of this driver is that supports monitor mode, and seems to export many low level parameters of the 802.11 protocol, providing much opportunity for hacking.

The disadvantage is that the driver uses its own set of configuration tools, rather than iwconfig and iwpriv.

Host AP Driver

As with the linux-wlan-ng driver, I could not get this to work with the stock firmware. I have yet to try this driver with the updated firmware. The interesting thing about this driver is that enables you to use a regular computer as a base station. While some of this functionality can be achieved using IEEE Ad-Hoc mode with other drivers, the Host AP driver makes your computer look just like a base station. The network created by the computer operates in BSS mode rather than IBSS mode. (IBSS mode is what you get by running other cards in IEEE Ad-Hoc mode.)

Nokia 3360 Mobile Phone

The interesting thing about this phone is that it has an IR port. There are two primary uses for the IR port. First, it can be used to connect a laptop or palmtop to the phone for access to cellular data services. Second, it can be used to manage the address book and calendar features of the phone.

Management of address book entries via IR is handled by exchanging v.Card files. So you can beam entries between mobile phones, PDAs, and suitable PC software. Unfortunately, the phone seems to be incapable of receiving more than one entry at a time.

There is a set of extended AT commands that some phones offer for management of address book entries. Unfortunately, the 3360 does not seem to be one of those phones. (But if you do have such a phone, Nokia HotSync is supposed to offer direct synchronization between such phones and Palm PDAs.)

Nokia has some software (Windows only) that synchronizes the 3360's address book with various Windows PIM software. This software does not have the limitation of dealing with only one address book entry at a time. Unfortunately, I have been unable to find any documentation on the protocol this software uses.

The latest versions of Gnokii have some support for the 3360. You'll probably need to get the latest version from their CVS repository.

D-Link DWL-900AP

A pretty inexpensive wireless bridge that has some interesting features. In addition to access point mode, the 900AP supports point-to-point bridging, and point-to-multipoint bridging. I have not had a chance to try these features.

The bridge will automatically configure a management IP address from your DHCP server if one is present. The included management software is Windows only. However, Access Point SNMP Utils for Linux reportedly works as well.

The antenna connector is reported to be reverse SMA.

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