I have a router (837).
I have assigned to the LAN behind the router a specific subnet picked up from our private IP addresses numbering plan. Our provider gave us an ADSL connection and provided 8 IP addresses (say a.b.c.8-15) plus a public IP for the WAN interface (say g.t.r.h)
The issue is that the provider cuts all the traffic having as source the WAN IP, the g.t.r.h.
I need to terminate a VPN on that router and at the beginning I thought not to care about the pool of 8 addresses and to use the WAN address. Obviously it didn't work and now I know why.
My question is:
how to have the private numbering (say 10.245.56.32/27) for the PCs connected directly to the router and have the VPN up?
AFAIK having a such scenario you need to have at least 2 Ethernet routers: the first one that divides the provider's net from that it has assigned to you and then another router with the IP address of the WAN interface picked from the pool. This way behind the 2nd router I can have my private LAN.
Ok how to compact this scenario and to manage it with only one router?
I hope this is not a big challenge.
I tried to use loopback interfaces without success, maybe I didn't use them in the correct way. Another solution proposed was to terminate the VPN (in the only one router available) on the Ethernet. That way requires the Ethernet to have a public IP taken from the pool assigned but I don't know how to have the same time the private IP for my LAN.
I'm sorry for the long post and I hope that other people faced the same problems and can help me.