OpenWRT and VPN Passthrough
Damn! This was easy! When I approached this I was fully prepared for a mega-Google session hours of swearing. In fact it took only a couple of minutes.
I have a VPN server running on a local machine in my network, like every sane person. When I'm out and about and need to mooch WiFi, I use my internet at home (as well as access local files, network and such) over the VPN. Not only more secure than throwing my data around in plain text over the local hotspot, but seriously handy (plug phone into car - navigate to music folder back home, play album I MUST HEAR RIGHT NOW, for example, as well as other, more serious uses).
So.. To cut a fairly short story even shorter you simply need to do (in OpenWRT)..
opkg install gre opkg install kmod-gre
You might also need..
opkg install install kmod-ipt-nathelper-extra
If you are using Chaos Calmer or later versions, you will instead need to do..
opkg install kmod-nf-nathelper-extra
Then add a section to your /etc/config/firewall
config redirect option name VPN GRE option dest_ip 192.168.0.3 option target DNAT option src wan option dest lan option proto gre
192.168.0.3 is the machine running the VPN server. You will also need a rule for the PPTP ..
config redirect option name VPN option dest_ip 192.168.0.3 option src_dport 1723 option dest_port 1723 option target DNAT option src wan option dest lan option proto tcp
Yup, that's it. After you restart your firewall..
You are good to go, as in go out, securely. Well, as securely as PPTP is, which is not very. Consider OpenVPN, instead!