Before I get into the details, let me describe what I need to do so that someone can stop me if this isn't going to work:
I have a GSM modem that will be connected into a remote network. It will not be the gateway or anything like that on the remote network, it will just be assigned a static IP in the network. I need to be able to access the devices on that network, i.e. I would like to, through VPN, be able to access IPs in the network the modem is connected to like normal. I need this because I have PLC/HMI software I will use with these devices and can't specify ports.
The GSM modem can initiate an OpenVPN tunnel (as a client). I have the following configuration screen available to me on the modem:
I can probably weed my way through most of the config file myself for the server, but I know I'm going to need help on settings like remote interface, local interface, address remote network, and the corresponding routing settings in the config file, because I really don't understand much about what's going on besides the fact that traffic is being routed over the tunnel as if they were connected by an Ethernet cable.
Will this work? My understanding of a VPN tunnel is that I'm basically joining the two physical networks together. So if the tunnel is initiated and I connect in to my local OpenVPN server, I should be able to access the devices behind the modem, yes? On what server environment will I have the greatest chance of success, Linux or Windows? I'm guessing Linux. I say it this way because the GSM modem also has IPSec server/client functionality and I've been trying to get that to work for about two weeks now with no success; the settings for strongSwan are hidden away and limited. I just want this stinkin' thing to work with sometime.
Any advice, tutorials, help, anything would be appreciated. Really not looking for anything elaborate here, I just want the simplest way to make this thing work (hence PSK, not certs). TIA
