Using any Debian box as a wireless access point
I just lost an hour trying to configure a Thinkpad T41 as a wireless access point. Most of that time was due to problems with the built-in wlan interface and a kernel recompile to use a prism54-based PCMCIA card. This is mostly a post to remind myself what to do, and how to do it on Debian. It's not the first time I create an access point, but I do it so infrequently that I always forget something.
The NIC
Make sure there's a Linux driver for your network interface card. Make sure the card can be run in master mode.DHCP
The boxes that will connect need an IP. Install dhcp3-server and do something like this in /etc/dhcp3/dhcpd.conf:[...] option domain-name "192.168.6.0"; option domain-name-servers 192.168.6.1; [...] subnet 192.168.6.0 netmask 255.255.255.0 { range 192.168.6.10 192.168.6.15; option routers 192.168.6.1; } [...]
Configure the network
Configure the interface so that it can be started with ifup. Usually you want the connected boxes to have access to whatever internet connection the access point has, so I enable forwarding and masquerading in /etc/network/interfaces:iface eth1 inet static address 192.168.6.1 netmask 255.255.255.0 network 192.168.6.0 wireless-mode master wireless-essid debianftw wireless-key1 s:12345 post-up /bin/echo 1 > /proc/sys/net/ipv4/ip_forward post-up /sbin/iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE post-up /etc/init.d/dhcp3-server restart13245 is the WEP password and the network will be called debianftw.
If you want DHCP and DNS, I'd install the "dnsmasq" package. This covers both services in one server and is much easier to configure than dhcp3 and bind.
Thanks for the suggestion! Configuring the Internet Software Consortium's dhpdc is indeed not that easy and might confuse some people.