OpenVPN: Assign a single URL to an IP

Question

I have a remote server that I am connecting to via OpenVPN. The OpenVPN-Server is configured not to forward ipv4 packages, so the "internet-traffic" does not go through the server.

Now I would like to assign a single URL to an IP address within the network. So for example: Whenever I am connected to the VPN and I enter random.org in my browser it redirects me to 10.8.42.12 within my VPN-Subnet.

I don't know, if this is possible or advisable? I have searched for a solution, but have not found one. Maybe because I am not using the correct terminology?

Any help or comments appreciated. Thanks! :)

Answer 1

You need to set a DNS A record somewhere, either on your VPN network or another network to which the clients can reach.

If you have a DNS server on the VPN network (or a network routable from the vpn connection) then you can configure openVPN to push DNS server addresses down to the clients so that when they connect, DNS's requests will go to the server you have specified that contains the A record you need. This set up means that the URL will only resolve to that IP when clients are connected to the VPN.

See this:

https://openvpn.net/index.php/open-source/documentation/howto.html#dhcp

EDIT:

I forgot to mention that consideration must be taken when changing out client DNS settings. The clients cache may still contain the lookup in which case you must look at setting the TTL on the A record so that it expires quickly.

Answer 2

use hosts file as in

10.8.42.12 example.org

or add entry to DNS server. create file with (e.g.) contents modifying the ns1.exampledns.com to point to a valid address

; Zone file for example.org
$TTL    3600
$ORIGIN example.org
@       IN      SOA     ns1.exampledns.com.    root.example.org. (
                                                     2012033101         ; Serial
                                                     3600         ; Refresh
                                                     1800         ; Retry
                                                     604800         ; Expire
                                                    43200 )       ; Negative Cache TTL

                IN      NS      ns1.exampledns.com.
                IN      NS      ns2.exampledns.com.

@       IN      A       10.8.42.12
www     IN      A       10.8.42.12

then add zone to /etc/bind/named.conf.local

zone "example.com" {
                type master;
                file "/etc/bind/db.example.org.conf";
};

Answer 3

Sure, the DNS solution as per tomstephens89 answer is one possible answer, but it works only if you type any domain name, and also that won't work if the client alter the DNS servers pushed by the server.

What do you really want is a solution, which is sometimes called Captive Portal. I am not strictly inside that topic, but SQUID which is a powerful HTTP proxy (which can be configured to be a transparent one - i.e. no configurations on client side needed) can help redirect the user to your page.