Problems bridging wlan0 and ppp0

[LinuxUserSlave]

I'm trying to create an AP that is bridged to a GSM USB card on ppp0 (10.2.112.188 ) so I can share that connection with other computers. (I live in an area where there is no other way to connect to the internet).

I have configured my wlan0 as an AP at 192.168.3.0. The dhcp3-server is passing out IPs to clients correctly, however I am unable to bridge the connection. And hostapd generates a "deauthenticated due to local deauth request" and drops the connection.

In the dhcp.conf I tried to point to my ppp0 port with this "option routers" as suggested elsewhere.

subnet 192.168.3.0 netmask 255.255.255.0 {
range 192.168.3.10 192.168.3.49;
option routers 10.2.112.188;
option ip-forwarding off;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.3.255;
}

I've also tried using the wireless-tools to make a bridge with the ppp0 and wlan0 but apparently ppp0 won't work (perhaps because it is ppp):

sudo brctl addif br0 ppp0
cant add ppp0 to bridge br0: Invalid argument

Also I tried adding the bridge command inside the hostpad.conf file

interface=wlan0
driver=nl80211
bridge=ppp0
ssid=TEST
channel=2
hw_mode=g
auth_algs=1
wpa=3
wpa_passphrase=testtest
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP CCMP
rsn_pairwise=CCMP

Does anyone have some other ideas that might work for me? I know that once the bridge is working I'll probably need to modify the IP tables to allow for NAT to handle the traffic but I'm not quite there yet I don't think.

[LinuxUserSlave]

The solution was two part. There was a problem with the hostapd.conf for WPA which caused the deauthentication problem. I just opened the network up and that problem went away so I'll have to look into that further.

Fixing the bridge was done through IP tables. I found that tool firestarter allowed me to bridge the PPP0 and WLAN0 connections pretty easily and I can also monitor the traffic with it.