Oh yeah. After I recently discovered that OpenVPN on the Fritzbox was the cause of all the grief I had with trying to connect two Fritzboxes via SIP over the Internet (tunneled, of course), and got rid of that (on the FB; my VPN-of-choice is still OpenVPN) and now even did a native Fritz-VPN link between two of them, I though, “hey, why not linking my Android to it as well?” Few I knew, back then, on how impossible this is with current, i. e. 2.3-ish, Android — the Fritzbox only does IPsec, Android only does L2TP/IPsec.
To cut a long (two nights, that is) story short: thanks to the awesome howto of Philip Bailey I got this going in next to no time — on a fresh Debian box, that is:
wusel@greebo:~$ traceroute dyn-130.mobile.uu.org
traceroute to dyn-130.mobile.uu.org (192.251.226.130), 64 hops max, 40 byte packets
1 gw.berlin.uu.org (193.26.120.113) 0 ms 0 ms 0 ms
2 gw-alice-b.vpn.uu.org (192.251.226.173) 27 ms 27 ms 33 ms
3 quoth.uu.org (195.71.106.48) 28 ms 31 ms 28 ms
4 dyn-130.mobile.uu.org (192.251.226.130) 101 ms 99 ms 101 ms
Cool stuff is: I now can happily start my VPN on the Android, start a SIP client and connect to my Fritzbox at home to take calls or make some — from my fixed line number, that is. I’m still not certain if I keep it this way or once again bring up my Asterisk. But for now it “just works” with two Fritzboxes, connected via a VPN (in this case, the FB in Berlin is the one hooked to DSL, the one doing SIP2ISDN in Gütersloh is actually a second one, as I seem to have some cabling issue on the ISDN side of the one in Gütersloh that does the PPPoE stuff) but not, this seems to be the important part, running OpenVPN locally.
I really would liked to connect directly to a Fritzbox from Android, but as I did not want to neither root nor custom-firmware all the Androids in my family, providing just a Android-compatible VPN gateways is the only approach.
