Re: AWL400 ping problem under Redhat 9

Hi,

On Wed, 21 Jan 2004, massimilianobonaveri wrote:

> iwconfig wlan0 essid maxHoc mode ad-hoc
> ifconfig wlan0 192.168.1.11
>
>
> When I ping from the Linux P.C the wireless ip adress it's all ok,
> but I can't ping another PC of the Lan
> for example my notebook (192.168.1.12).
>
> >From my Notebook (Window Xp) I see the wireless Lan  but I can't ping it....
>
>
> I think the configuration is OK:
>
> # ifconfig
> eth0      Link encap:Ethernet  HWaddr 00:00:1C:B5:C7:49
>           inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:949 errors:1 dropped:0 overruns:0 frame:0
>           TX packets:659 errors:3 dropped:0 overruns:0 carrier:3
>           collisions:0 txqueuelen:100
>           RX bytes:559340 (546.2 Kb)  TX bytes:46208 (45.1 Kb)
>           Interrupt:9 Base address:0x2000
> ...
> wlan0     Link encap:Ethernet  HWaddr 00:03:9D:4B:1E:24
>           inet addr:192.168.1.11  Bcast:192.168.1.255  Mask:255.255.255.0
>           UP BROADCAST  MTU:1500  Metric:1
>           RX packets:119 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:100
>           RX bytes:18467 (18.0 Kb)  TX bytes:60 (60.0 b)

I'm rather a routing-newbie, but IMHO this config is wrong.
You've got two network devices with IP addresses in the same subnetwork
(192.168.1.X/24). How should the stack be able to determine if it should
use eth0 or wlan0 for e.g. an outgoing IP packet to 192.168.1.12?
Have a look on your routing table ("route -n").

> This is my log when I try to connect to Linux Redhat 9.0 from my notebook:
>    Wireless  Linux IP Adress 192.168.1.11
>    WireLess NoteBook IP      192.168.1.12
>
>
> root@ServerHome root]# ping -c 1 192.168.1.11
> PING 192.168.1.11 (192.168.1.11) 56(84) bytes of data.
> 64 bytes from 192.168.1.11: icmp_seq=1 ttl=64 time=0.081 ms

I assume ServerHome is the machine which got the above eth0? You ping an
IP address of a local interface, these packets are not even passed to any
network driver.

> [root@ServerHome root]# ping -c 1 192.168.1.12
> PING 192.168.1.12 (192.168.1.12) 56(84) bytes of data.
> >From 192.168.1.1 icmp_seq=1 Destination Host Unreachable

I guess the packets leave on eth0 only (as your tcpdump suggests), but
there is no 192.168.1.12 on the wire. To test this, just shutdown the
192.168.1.1 on ServerHome ("ifconfig eth0 down") and try to reach it from
the WinXP Notebook.

You may either:

a) use a different subnet, e.g. 192.168.2.1/24, for the wireless network
and let the ServerHome do "ip forwarding":
ServerHome: eth0 - 192.168.1.1
            wlan0 - 192.168.2.1

WinXP Notbook wlan - 192.168.2.2 with default gateway 192.168.2.1 (no
                               idea how to configure it with WinXP)

This should allow you to ping etc. ServerHome from WinXP under both
addresses 192.168.1.1 and 192.168.2.1 and also all other hosts in
192.168.1.1/24.

or b)
Use the same subnet for wired and unwired media and configure ServerHome
as a bridge (similar to a WLAN access point which doesn't route - don't
ask me how to do so).

/Jörg