Bridging wifi to ethernet

[Les Mikesell]

On Sun, 2006-02-05 at 13:58, Douglas Phillipson wrote:
> > 
> >>My LUG recently had to move to a Library with WIFI access only.  Running 
> >>FC4 on my HP Pavilion laptop, how specifically, can I bridge my WIFI 
> >>interface (eth1) over to my eth0 interface so I can hook in all the 
> >>wired ethernet users to get access to the WIFI networks DHCP server?  I 
> >>don't have to recompile a Kernel I hope...  I can still use my laptop 
> >>normally while I'm bridging for everyone else I hope?
> > 
> > 
> > A simpler approach that is also more likely to work would be
> > to set up a different private address range on the wired side
> > and a dhcp server for it, then route and NAT to the wireless
> > interface.   The only tricky part is that you either have
> > to run your own caching dns server and point the dhcp clients
> > to it, or you'll have to pick up the DNS server you receive
> > from the wireless DHCP and edit your dhcpd.conf to pass that
> > on to the clients.
> > 
> 
> The magic  part I don't know how to do is "route and NAT".  Can you 
> point me to an example on how to route and NAT between interfaces?  Is 
> this a IPTables thing?

You just need to:
 modprobe iptable_nat
 iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE
 echo 1 > /proc/sys/net/ipv4/ip_forward

And make sure any other firewalling lets what you need through.
You should get a default route via dhcp on the wireless side
and one will be added by the netmask for your private wired
side so you don't need to add any extra routes.

-- 
  Les Mikesell
   lesmikesell at gmail.com