NAT Gateway by iptables dnsmasq

The following guide can be followed on the palm to make a NAT gateway from a usb0 (tether) to ppp0 (EVDO). It is also possible this can be adapted to use a palm pre as a usb wireless adapter, that is NAT gateway from usb0 to eth0.

https://help.ubuntu.com/community/Internet/ConnectionSharing

Shut of the Wifi connection on palm

You will need to shut off wifi on your phone (it won't work otherwise). To do this tap on the upper left hand corner where the wifi icon is. Select "Wi-Fi" -> Turn off Wi-Fi

Turn on USBnet on palm

get a root terminal and enter the commands: This requires a reboot so exit anything you're doing on your phone.

usbnet enable
reboot

Make dhcp/dns availalbe to usb0 (only do once)

get root terminal and use the following to make dhcp/dns available to usb0

mount -o remount,rw /
echo interface=usb0 >> /etc/dnsmasq.palm.conf
echo dhcp-range=192.168.2.2,192.168.2.3,2h >> /etc/dnsmasq.palm.conf
stop dnsmasq
start dnsmasq
mount -o remount,ro /

Setup packet forwarding

ifconfig usb0 up
ifconfig usb0 192.168.2.1
sysctl -w net.ipv4.conf.default.forwarding=1
sysctl -w net.ipv4.conf.all.forwarding=1
iptables -t nat -A POSTROUTING -o ppp0 -s 192.168.2.0/24 -j MASQUERADE
iptables -t nat -A PREROUTING -i ppp0 -p tcp --dport 3074 -j DNAT --to-destination 192.168.2.2
iptables -t nat -A PREROUTING -i ppp0 -p udp -m multiport --dports 88,3074 -j DNAT --to-destination 192.168.2.2
iptables -A FORWARD -i ppp0 -d 192.168.2.2 -p tcp --dport 3074 -j ACCEPT
iptables -A FORWARD -i ppp0 -d 192.168.2.2 -p udp -m multiport --dports 88,3074 -j ACCEPT

Setup your computer

On Ubuntu Linux 10.04 in network manager right click the icon select "Edit Connections". Find the wired interface probably named "Auto usb" edit and uncheck "connect automatically" box.

Windows / Mac instructions coming soon.

Trouble Shooting

Make sure both these values are 1.

sysctl net.ipv4.conf.default.forwarding net.ipv4.conf.all.forwarding

Beware, the palms seems to like setting this to 0 whenever network settings are changed.

References

http://forums.precentral.net/palm-pre/272021-pre-gateway-via-iptables-possible.html