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April 4, 2012

Link 2 computers by wifi with httpd allows only one way trafic

Hello all.

I have a small problem, I'm trying to connect two computers directly creating in one of them an AP using hostapd.
I more or less followed this: https://www.linux.com/learn/tutorials/442417-create-a-secure-linux-based-wireless-access-point

I've managed to create my AP without trouble and connected my other computer to it, but they cannot ping each other.
At first I thought it was a problem assigning IP's, so I decided to use static IP so I don't have to use a dhcp sever.

My client is with netmask and my AP is with the same netmask.
I configurated them using ifconfig wlan0 129.168.127.XXX netmask
So I tcpdumped both connections to see what was going on and ping'ed.
If I ping from my AP to the other computer:
ping -I wlan0
I get this in my AP's tcpdump (using tdpdump -i wlan0):
ARP, Request who-has tell, length 28
Nothing else, no reply nor anything.

But, in my client's tcpdump I get:

ARP, Request who-has tell, length 28
ARP, Reply is-at XX:XX:XX:XX:XX:XX (oui Unknown), length 28

So my AP is not receiving the reply but my client receives the ping request.

If I do it the other way (Ping from the client to the AP) the client tcpdump shows that it is trying to send the ARP request, but the AP does not log anything at all.

I'm confused. I don't really know much about networking but I feel that something odd happens here. For example, the AP does receive some data because I can connect both computers and hostapd shows that the authentication is correct.

My AP is OpenSuse 11.4 and the client right now is BackTrack linux, but later I plan to use a debian and a windows computer as clients.
Also, I've been using linux for a long time, but with my wifi I've always used some kind of GUI like kdenetworkmanager so I don't really know how to do everything properly with the console, and maybe I'm skipping something important.
I stopped my firewall in the AP just in case.

Thank you very much in advance!

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