Wireless is more fun then fishing for Bass while drinking a Bass. Open your home pantry and you have a wide range of homemade antenna options. What can you do with some of those older WLAN cards stuffed in a office drawer behind the "Must Read" stuff from Human Resources?
I was stuck at a meeting with only one Ethernet cable for Internet access to be used between 25 people. Now, I am NOT a meeting kinda a guy. You have me for about 17.435 minutes and then I am in code mode drifting the mental currents of time. Now, Internet access would be cool, but some other knob got in the room before me and took the only cable.
Being a hacker at heart, there are no closed doors, only opportunities. (great bumper sticker idea right there!) I keep many things in my laptop bag. Most of it is food, but some of it is hackin’ gear. I just happened to have my trusty Hermes Wireless LAN card… One homemade access point coming up! I built out an home brew Linux imagine a while back to take advantage of such an opportunity as this.
The Hermes (Orinoco) based radio card is a bigger pain in the tail to operate in BSS master mode then going to a cookout where folks are using only gas grills. By design, the cards themselves are actually not able to provide BSS master services on their own. Before these cards can operate as a BSS master, they need additional firmware uploaded to the card. This tertiary firmware is uploaded to the card's RAM, and is lost if the card loses power. To make matters even more difficult, the firmware in question is licensed software, and can't legally be distributed by anyone but the manufacturer.
The awesome folks at Hermes AP project http://hunz.org/hermesap.html addresses both of these issues. (I have noticed that site is not online, but the code can be found many places on the Internet) It consists of:
- Set of modified drivers
- Utility for uploading the tertiary firmware
- Script that downloads the firmware from Proxim's public FTP server.
A Host AP isn't as easy as Sunday Morning to get up and jamming, but can be the stuff if you are stuck in a snoozefest of a meeting and need Internet access to keep from snoring louder then the speaker is yammering on about profit margin opt in variables or something...
To get Host AP running, you need a Linux kernel with the Dev FS enabled. This allows the kernel to manage the /dev directory, dynamically creating device files for every physical device that the kernel supports.
Run a make menuconfig, and select:
-Code maturity level options
-Prompt for development and/or incomplete code/drivers
Now go back to the main menu, and under File systems enable:
- /dev file system support and automatically mount at boot.
When running Dev FS, it is a darn good idea to disable /dev/pts file system support since Dev FS will automatically manage your ptys for you. Before you recompile your kernel, copy all of the source code under the drivers/ directory from Hermes AP over top of the existing drivers in the kernel (right over top of the files linux/drivers/net/wireless/). Now build your kernel and modules as you normally would, and reboot. Your Hermes card should come up as usual with the new driver, but won't support BSS Master mode yet.
First, cd to the Hermes AP source directory. To download a copy of the tertiary firmware from Proxim's site, run the hfwget.sh script in the firmware/ directory. Next, build the hfwload utility by running make in the hfw/ directory. This utility uploads the tertiary firmware to your card. Copy the utility and the card firmware somewhere handy (I keep mine in /usr/local/hermesap) and run a command like this at boot time, before the interface comes up:
# cd /usr/local/hermesap; ./hfwload eth1 T1085800.hfw
The card must NOT be configured as up when you load the firmware. A simple iwconfig command will show that eth1 is in Master mode! You can now configure the radio with an SSID and free access for all!!
Now back the pantry analogy, more then just sucky potato chip cans can be effective antennas; same goes with WLAN cards. Folks that have Intersil chipset based cards can use the program HostAP located at http://hostap.epitest.fi and do the same thing so you are never without the ability to have an access point in your bag. Now back to the actual pantry, I am gettin' hungry...
Jimmy Ray Purser
Jimmy Ray Purser is the technical co-host for Cisco's TechWise and BizWise TV. Jimmy Ray also conducts advanced training for engineers across North America and Europe and regularly speaks at industry conferences such as VON, CeBIT, N+I, and Networkers. As a field engineer, Jimmy Ray experiences networking first hand behind the console or in the rack. He is an active member in the IEEE and the Ethernet Alliance and has designed, installed and tested numerous networks for Fortune 500 companies, the United States military and other institutions worldwide. He holds 3 U.S. patents for Ethernet security algorithms with two others pending and one defensive publication, as well as numerous other vendor certifications in networking and security.
Purser holds a Bachelor of Science degree in electrical engineering from Southern Illinois University is currently pursuing a master of science degree in electrical engineering.