PPTP/L2TP Internet

[n1nja]

Hi All,

My ISP is one of the smaller ones that uses PPTP/L2TP to run over other companies wires to give me internet.  Currently they gave me a mikrotik in which I connect OPNsense to (protectli appliance) and the mikrotik and protectli each get an IP out of a public /30.

I can see on the mikrotik the "connect to" IP address, where my credentials go as well.  I don't see source IP address configuration so it's kind of like black magic to me.

I'm confused on the roles involved with my actual physical WAN interface (em0) and the "Point-to-Point" section.  They sort of seem to overlap and I'm not sure what goes where.  Right now the mikrotik has a static for the other IP in my /30 and dishes out DHCP for the remaining IP to my firewall.

Should my WAN interface be changed from DHCP to PPTP (or L2TP, as I think my provider accepts both... but one step at a time here)?  If I do this it is asking for a local and remote address below.  I don't know what these are.  I've just been given a gateway IP which is RFC1918 (172.16.X.X) and my public IPs.  I would assume the remote box would contain the "Connect To" IP address I see in the PPTP config on the mikrotik.  But not a clue what the local address or mask would be.

I'm sorry if this is confusing but I really don't understand how this is supposed to work at all.