Building a Wireless Network with Linux

Want your laptop and PC to talk to each other without having to deal with wires? Here's how.
Bridging: An Alternative

I found out you also can easily build a wireless bridge, and thus not have to use routing to allow a wireless connection to connect to the rest of a LAN. Using a spare laptop, I first recompiled Linux to enable bridging. I then installed an eth0 interface with an assigned IP address to connect to the LAN. Next, I installed the Aviator card as eth1 without an assigned interface, then brought up both interfaces in promiscuous mode with

/sbin/ifconfig eth0 promisc up
/sbin/ifconfig eth1 promisc up

Next, I downloaded Alan Cox's brcfg utility, and enabled bridging with

 ./brcfg -ena
After starting a wireless connection, I could then access any computer on the LAN from the wireless laptop.

Conclusion

Wireless networking may not be the best solution if you need high-speed communication on or between your LANs, but the combination of Linux and a legacy laptop shows that you can build a useful and flexible wireless network at low cost. This is just one of the reasons I use Linux (besides being able to surf the Web while drinking a pool-side Margarita—with salt, on the rocks, thank you).

Resources

Acknowledgements

Bill Ball is a member of the Northern Virginia Linux Users Group (NOVALUG), and the author of nearly a dozen books about Linux. He may be contacted through http://www.tux.org/~bball/.

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