[Gllug] Wireless to wired LAN router

[Pete Ryland]

Hi Simon,

It's probably not the router's fault, but the fact that your 192.168.1.x
hosts don't know that bix is the router for the 10.x.x.x subnet.  That is,
on host 192.168.1.7, for example, you will have the routing table:

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
default         192.168.1.2     0.0.0.0         UG    0      0        0 eth0

So packets for 10.1.0.2 will happily be sent to 192.168.1.2 and subsequently
dropped.  Use traceroute to confirm.

You can fix this by doing:

# route add -net 10.0.0.0/8 gw 192.168.1.20

on each of your 192.168.1.x hosts.

Actually, what's the routing table on the Net GW look like, since it can get
to the 10.x.x.x network?

Anyway, John's solution is much easier (and is what I do here).

Pete

On Sat, Nov 16, 2002 at 12:08:04AM +0000, Simon Stewart wrote:
> Right, I'm obviously missing something obvious, so I thought that it's 
> best to ask the experts. Apologies if this is something of a rather 
> long email, but I'll try and put enough information in.
> 
> At home I have a wired LAN already, and I'm keen to set up a wireless 
> LAN too. Addresses on the wired LAN (on which my ADSL router sits at 
> 192.168.1.2) are in the range 192.168.1.0/24. Wireless clients are 
> allocated IPs in the range 10.1.0.0/24.
> 
> Obviously, I need to set up a machine that sits between the two 
> networks and acts as a router. This has got two NICs in, one of which 
> is wireless, one of which is not. The network config looks likes this 
> (internally)
> 
> NET -> 192.168.1.2 -> 192.168.1.20 -> bix -> 10.1.0.1 -> 10.1.0.2
>        Net GW         Wired NIC      router  Wireless    Wireless
>                                                NIC       clients
> 
> Bix is the machine that I'm setting up as a router. It's running Debian 
> 2.4.19 and its routing table looks like:
> 
> Destination     Gateway         Genmask         Flags   MSS Window  
> irtt Iface
> 192.168.1.16    0.0.0.0         255.255.255.255 UH       40 0          
> 0 eth0
> 10.1.0.1        0.0.0.0         255.255.255.255 UH       40 0          
> 0 wlan0
> 192.168.1.0     0.0.0.0         255.255.255.0   U        40 0          
> 0 eth0
> 10.0.0.0        0.0.0.0         255.0.0.0       U        40 0          
> 0 wlan0
> 0.0.0.0         192.168.1.2     0.0.0.0         UG       40 0          
> 0 eth0
> 
> The wireless interface is in Ad-Hoc mode. From my iBook (10.1.0.2), 
> which is the only wireless client I have atm, I can ping as far as the 
> wired NIC on the router (that is, 192.168.1.20) and no further. From 
> the Net GW I can ping as far as 10.1.0.1. Bix can ping every host on 
> both networks, so it's not that something is running a firewall that 
> doesn't let me ping anything. :)
> 
> The same behaviour is seen when /proc/sys/net/ip_forward is either 1 or 
> 0 on the router, and the kernel has been compiled with support for 
> being an advanced router enabled.
> 
> What I really want to do is to allow all the hosts on both networks to 
> see each other, so I'm not keen on setting up ip masquerading in order 
> to get this working (where's the challenge in that?) Other useful 
> information: the iBook claims to be in a "Computer to Computer" 
> network, rather than a more normal "airport" network, but I understand 
> this to mean that it's in ad-hoc mode too, rather than being some 
> bizarre peer to peer config --- I haven't seen any docs saying 
> otherwise.
> 
> Any ideas on how to sort this out? It'd be great to be able to get this 
> going properly. If anyone can also give me some pointers on how to make 
> bix appear as a full fledged access point, that would also be 
> appreciated. I've already googled and found the "host ap" driver for 
> the Prism 2 cards and even with this installed the iBook isn't fooled, 
> but that's a problem for another day....
> 
> Cheers,
> 
> Simon
-- 
Pete Ryland
http://pdr.cx/

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