Newbie question about setting few vpn

[pdarkfury]

Hey i got a teoritical question about the openvpn acess, and sorry for my english already.
Is it possible to set connections of few different lans over the internet to one openvpn server which is also on the lan side?
The thing is that there are 3 companies with no static ip wan adress we would like to have vpn to (they will use dyndns if this is needed) . All 3 lans in those companies got different lan adresses. The thing which we would like to achieve is to be able to get into their networks as normal lan users so i belive the brigging vpn is the right thing. Also there is no chance we could allow to let the companys sees each other on the lan.
I was thinking to making a server on our place and instal openvpn clients there in each of their networks but maybe they also need to have the vpn servers ? Anyhow we have only 1 wan going on the world so i dont know if this possible also because i m guessing i would need 3 tap devices also to bridg with our local connetion.
Any help will be very helpfull

[janjust]

a single VPN server on a remote site would work just fine; you can run multiple VPN instances on a single server to completely separate the traffic between the 3 companies; the companies the connect as clients to your VPN server.

[pdarkfury]

Ok, great but i still wonder how it should be settled. As more i read about it as more i am confused...
We would like to get into the clients LAN networks but they cannot see our network and also not each other from different companies. Also we would like to connect 2 lans from one company trough the VPN.

Please correct me if i am wrong, coz we have 3 different companies to have tunnels to:
If we would like to settle openvpn server in our place and install clients in those companies,
1) Should we install those clients in each computer in those companies or would be enough to install it on 1 computer with a TUN IP from their LAN network to be able to connect to every computer there, because i guess we would need 3 different TUN devices to each of the company on our server ? or am i wrong?

My questions is what is the best solution to have such a VPNs working correctly.
From what i read vpn pver ethernet protocol is way better solution but i guess in our case it is not possible to bridge 3 tap and 1 local connection because then they would be in same ip adress range.

I know that the best solution would be to install servers in each company and we like a client would connect to their networks but this is something which we have to avoid.

[janjust]

set up a single server at your site; make sure the 3 companies can reach it. Set up 3 different instances of openvpn, each with their own certificates; configure 1 client at each company to connect to a separate openvpn instance. Presto.

[pdarkfury]

Thanks m8