swapping a vpn from one routing to another

[dexdyne]

I'm running a linux-based product which works over an ADSL network, but if the ADSL goes offline, it starts up a GPRS link, and drops back if th ADSL recovers.

Some installations may only have one or other.

I want a VPN to our server, over whatever routing is open.

I'm trying to load openVPN at start-up, and if the link moves from one routing to another, I send SIGHUP ( I think I could probably change that to SIGUSR ) and tell it to renew the VPN connection.

Can anyone see anything wrong with this approach?

There is a bit of an issue once one link goes down , and while I'm trying to establish the other.
What I would LIKE to do is to load the openvpn s/w at power-up, but be able to tell it "there there, I know you can't talk to anyone at the moment, but don't fret, I'll give you a signal when I think you should try again - in the meantime, keep quiet."

the dhcp driver I use has such a "load and do nothing" option, but I haven't seen a way to ask openvpn to sit quiet and wait.

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by-the-by... I find that if I change the routing tables ( from the ADSL to the GPRS set-up ) "under the feet of openvpn", it loses the vpn - I was sort of hoping that it would keep it going as soon as there was a valid routing to the "other end" again.

Does anyone think that this "ought to work now" or "ought to possible" or alternatively "is simply impossible" ????

[krzee]

check the manual to see if --float or --ipchange suit your needs

[dexdyne]

-- float

My "remote end" isn't going to change it's IP address, what is going to change is my route to it.... so adding this at my end is not going to help in an obvious way.

HOWEVER

Of course adding this option at the 'server' end may be exactly what is needed, as my unit will indeed appear to have changed it's IP address as far as that end is concerned.

TVM

D