Re: [gentoo-user] OpenVPN and DHCP

[Thomas Rösner]

Hi,

Patrick Holthaus schrieb:
> Hello everybody!
>
> Maybe this is a bit Off-Topic here, but maybe some of you like to help me
> anyway.
>
> I am trying to build a VPN network where the clients get their IP adresses
> from a local DHCP server (because it should notify the nameserver of the
> clients). The VPN should have its own adress pool 10.8.0.* while the
> unsecured clients in the server's LAN should get an 192.168.1.* adress.
>
> I got the VPN working but the clients do appearently not get their IP from the
> DHCP server but some random IP from the OpenVPN server. (The DHCP server only
> assignes 10.8.0.100-200 adresses but the clients get .8 or .10 for example)
>
> Now my questions are:
> Do I need bridging for making the DHCP server work in the VPN?
>

Yes. DHCP is an ethernet protocol. DHCP over IP wouldn't make much 
sense, would it? To use your existing DHCP Server you need OSI Layer 2 
VPN connections (TAP devices).

> How should the configuration files look like?
>

Uhm, in your testing files, you try to configure IP's on a tap device? I 
think you mix the concepts up here. If you have a tap tunnel, your 
client sends ethernet frames to the server, who, when properly bridged, 
sends them to a local LAN, and vice versa. No IP involved on that level, 
you could use IPX or SCTP if you wanted. The only IP you mention in the 
config file is that of the server.

But then a client could connect and use any IP you ask? Well, yes, as in 
any LAN. You can use iptables on the bridge to filter spoofed packets 
out, though.

It's more easy and faster to stick with Layer3 vpn, though.

Regards and HTH,
    Thomas
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