Networking issue

H.S. hs.samix at
Tue Apr 7 17:04:36 UTC 2009

Jose Rodriguez wrote:
> Hello everyone!
> Here is my problem, hope someone can help.
> Im trying to setup a wireless network with my Pc as a wireless router.
> I have a Broadcom wireless card and im using Ubuntu 8.04.
> For the configuration of the network i followed these instructions:
> For the configuration of a DNS and DHCP i followed these:
> I basically:
> - Configured /etc/network/interfaces with eth0, which has an IP assigned
> dinamically by the router/modem; and also configured wlan0 interface with an
> IP static.

It appears that you have a LAN cable connecting your eth0 to your
modem/router's LAN port. I would assign a static IP to eth0. This
simplified things and makes debugging for problems easier.

> - I tested connectivity, everything fine.
> - Then configured a DNS/DHCP server using dnsmasq.

Make sure that it is *not* listening on eth0 (the interface connected to
your modem/router) for DHCP requests because you must always have only
one DHCP server on a network. Your modem/router and eth0 is one network,
and rest of the interfaces on your computer (eth1, wlan0?) are other
different networks. BTW, it would be a good idea to specify what are all
these three networks in your case?

Also, is this picture correct?
   ____________   lan cable    |             eth1|-> to a switch?
->|Router/Modem|>--------------|eth0        wlan0|-> wireless clients
   ------------                |_________________|

                                     |______Ubuntu computer

> - Finally NAT with a script as the link above can show you.
> I dont think the DHCP was working so i deactivated.

Yes, good idea. Just to make sure everything is working, you can always
give other computers a static IP address.

> My problem is, i have internet in my pc/wireless router but when i try to
> connect my cellphone or another Pc or my Ipod to the wireless network i
> created i dont have access to internet. I assigned an static IP to every
> device but i cant navigate.

What about wireless encryption? Are you using any? For now, I would
suggest you disable all encryption.

Also, what is the output of the following command:
$> ifconfig -a

> From the router i ping every interface and it works but when i try to reach
> other host supposedly connected with ping, i cant reached it. Same if i try
> from a Pc to the router. What am i missing here??? I thought it could be a
> bad assigment of IP address but for my eth0 im using, and
> for my wlan0 im using The hosts then would have

Correct, your eth0 is on network and wlan0 is on
network. If you wlan0 is assigned, then your hosts can have
any of the 2-254 IP addresses.

I see that you have only one wired interface (no eth1).

> Then only thing i could think of is that when i configured my wireless card
> they recommend to set it as a master mode, but i havent been able to make it

What exact card is this?

> support that. I set it in ad-hoc mode which it suppose to work as well.

I think you need it to work in master. What did you try to do so? Also,
what wireless manager are you using (one is hostapd)?


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