VPN - how does it work
Posted on 2006-03-30
I understand what VPN is and have been trialling with RRAS and doing some reading, internally i have set up a RRAS server and can connect to it just fine with an xp machines inbuilt VPN connection.
I also understand that at my office i would have to enable port mapping on a router to point to my VPN server - 1723 for PPTP
The concept i do struggle with however is, If i am sitting at home with a normal DSL connection through a standard ISP, how do i authenticate with my VPN connection, to my RRAS server which sites behind a firewall in a private IP managed network, or scrapping the private IP managed side of things, a standard network that sits behind a router with a different ISP on the other side of my country!
for example my home network in New South Wales sits quite contentedly with a 192.168.X.X IP scheme which is doled about by DHCP on my router. Now my imaginary office in Western Aus sits on a standard network that also sits on a 192.168.X.X IP scheme that is once again doled about by my standard ADSL router.
how does this work - i know it does but i would like to understand how it is done. How do Site to Site full time VPN tunnels configured through RRAS stay up sot hat DC's can replicate! this is a mystery to me! just want to know how in the world my home laptop knows where to go with the millions of ADSL routers out there dolling out 192.168.X.X Ip schemes for home LANS! i know it pulls on the WAN address but i still dont understand it!
Thanks for your expertise!
i dont need links on how to set them up as i have plenty of them and have handed them out to people with questions in the past - i get how to set them up to a point. what i want to know is How this works!!
if this is to much of a broad question let me know and ill narrow it down if i can