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 restart

13245 is the WEP password and the network will be called debianftw.

Optional: DNS

You may want to have name servers for the connected boxes. A quick solution is to take those from your /etc/resolv.conf and to put them in your /etc/dhcp3/dhcpd.conf. There are other solutions, like a caching only DNS server.

Security

WEP isn’t a very good encryption but it’s enough for me. You probably don’t want to run this setup for a long time, it’s really just some notes to get me started quickly. Maybe I’ll add more about security in an update.

Another problem can happen when you use cookies. If not done correctly, your user’s cookie won’t be available to the website when they were stored under www.domain.com and he uses domain.com the next time he visits. See the cookie specs for more details.

A quick research led me to a solution for apache that I didn’t like too much. It involves using mod_rewrite. mod_rewrite is a great tool, but there’s a better solution for redirecting to your main domain from subdomains or second level domains. Simply use a catchall virtual host in your apache host configuration file(s) to do the redirects. This will solve all the SEO, caching and cookie issues, and it will save some CPU cycles compared to the mod_rewrite or higher level solutions.

# NameVirtualHost *:80
 
<VirtualHost *:80>
    ServerName www.domain.com
    # This is your main domain
</VirtualHost>
 
<VirtualHost *:80>
    ServerName domain.com
    ServerAlias *.domain.com
    # This is to make sure that foo.domain.com gets redirected too
    # If you want to use more virtual hosts on subdomains,
    # just define them earlier
    Redirect / http://www.domain.com/
</VirtualHost>

Please refer to the mod alias docs to decide which Redirect you need, this example uses a 302.

For lighttpd you can use this:

$HTTP["host"] =~ "domain\.com" {
    $HTTP["host"] != "www.domain.com" {
        url.redirect = (
            "^(.*)$" => "http://www.domain.com$1",
        )
    }
}

By the way, if you’re an IIS user, you might want to read this.