[Gllug] Wireless to wired LAN router

Ian Norton bredroll at atari.org
Sat Nov 16 11:50:26 UTC 2002


ive got several lans wired together and a few wireless kicking about too,

heres what ive done

mercury - p90 laptop (wireless card and 10/100 card)
earth - 686 server (cable line, network 1, network 2)

earth is the main center of everything, heres the diagram


 { 100mbit Lan (10.3.x.x) }--------{ earth 10.3.1.1 }------{ ntl
                                    /
              { 10mbit Lan (10.2.x.x) }
                   /
          { mercury 10.2.0.2 }

earth - routes
Destination     Gateway         Genmask         Iface
10.2.0.1        0.0.0.0         255.255.255.255 eth0    // 10mbit card
10.3.1.1        0.0.0.0         255.255.255.255 eth2    // 100mbit card
62.254.117.0    0.0.0.0         255.255.255.0   eth1    // Cable line
10.2.0.0        0.0.0.0         255.255.0.0     eth0    // 10mbit lan
10.3.0.0        0.0.0.0         255.255.0.0     eth2    // 100mbit lan
10.4.0.0        10.2.0.2        255.255.0.0     eth0    // wireless lan   
127.0.0.0       0.0.0.0         255.0.0.0       lo
0.0.0.0         62.254.117.254  0.0.0.0         eth1    // internet

mercury routes
Destination     Gateway         Genmask         Iface
10.2.0.2        0.0.0.0         255.255.255.255 eth0    // ethernet card
10.4.0.1        0.0.0.0         255.255.255.255 wlan0   // wireless card
10.2.0.0        0.0.0.0         255.255.0.0     eth0    // 10mbit lan
10.4.0.0        0.0.0.0         255.255.0.0     wlan0   // wirless lan
127.0.0.1       0.0.0.0         255.0.0.0       lo
0.0.0.0         10.2.0.1        0.0.0.0         eth0    // gateway to world

the machines have ipforwarding enabled, earth uses masquerade for the cable
line, both have iptables firewalls set up, the laptop with wireless has a very
tight set of rules, it only allows in/forwards TCP/22, TCP/25 TCP/80, DHCP, and
UDP/26000 (quake)

i hope this is useful :-)

bredroll




On Sat, Nov 16, 2002 at 12:42:10AM +0000, Pete Ryland wrote:
> 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/
> 
> -- 
> Gllug mailing list  -  Gllug at linux.co.uk
> http://list.ftech.net/mailman/listinfo/gllug

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