Openvpn – How to set up OpenVPN to let the VPN clients to access all the servers inside the server LAN

It looks to me like the server is pushing the "redirect-gateway" option down to the client. This causes the client to use the VPN as its default gateway. Comment out the line in the server config 'push "redirect-gateway def1"'.

Woah there-- just saw your edit. You client can't be using the same IP addresses as the LAN it's connecting to. That's not going to work. One end or the other needs to use different IP addresses.

Edit:

Assuming routing is configured properly on your Windows Server 2003 machine (per the www.itsatechworld.com page you referenced), you should be able to PING the Windows Server 2003 machine and Windows Vista machine by their LAN IPs via the VPN. If you can, then you've got routing right on the Windows Server 2003 and DD-WRT machines and you can proceed. If not, then you need to start tracking down why either (1) PING traffic coming off the OpenVPN tunnel isn't getting to the destination, or (b) why PING replies from the destination host aren't coming back. You may end up putting something like Wireshark on your Windows Vista machine to see if the PING requests are even getting there (since PING can't tell you if your request is being received and the reply is just being lost).

Once you've got IP connectivity across the VPN working fine. I'd recommend installing the DNS and WINS services on your Windows Server 2003 VPN server computer and configuring the server computer and the Windows Vista home computer to use that machine for WINS and DNS. You can either add your ISP's DNS as a "forwarded" on the Windows Server 2003 machine, or leave the stock "root hints" configured to allow it to resolve Internet names. In your OpenVPN server configuration, add the following line right after the 'push "dhcp-option DNS 192.168.1.1" line:

push "dhcp-option WINS 192.168.1.1"

This is going to get the remote clients taking to the WINS and DNS servers on your Windows Server 2003 machine, and should get you both DNS and NetBIOS name resolution.

If you're not using an Active Directory domain at home, you'll probably want to setup a standard forward lookup zone on the Windows Server 2003 DNS server for your Windows Server 2003 and Windows Vista machines to register into. You'll want to grant clients permission to dynamically update records (albeit insecurely) when you create this zone. You should add the option "DNS domain name" (option 15) to your DHCP scope at home so that your client computers there pick up the right DNS domain name suffix. (If you're using DD-WRT for DNS then I can't tell you how to do that. I'm an OpenWRT guy, and I manage my WRT54G from the command line. I'd recommend running DHCP from the Windows Server 2003 machine anyway, but I just like that DHCP server more.)

If you are using an Active Directory domain you'll already have a forward lookup zone created in DNS. Since your remote VPN clients aren't members of your domain, though, they won't be able to register in DNS under the stock security settings that Windows Server sets on the DNS zone (at least, if you let it create the zone during DCPROMO). It's insecure, but if you want to allow them to register you could either (a - less secure) chang the permission on the zone to allow insecure registrations, or (b - more secure but still insecure) create A and PTR records for them and modify the permission on each of those records to allow anyone to update them.

It sounds like this is a home networking thing, and it's really a good learning opportunity for a lot of things-- IP routing, VPNs, name resolution. Perhaps you're looking for it to "just work" and not as a learning opportunity, in which case I can only offer my apologies and say that these things just aren't "turnkey" yet.

you're doing it wrong.

1st - use layer 3 connections instead of layer 2 for vpn. Saves traffic.

2nd - use brouting to get the trick done with proxy-arp and assing ip addresses from the local subnet to the vpn clients - so they just appear as they're local

3rd - or use routing and set the route to the clients in the 10.22.8/24 subnet on all systems in the 192.168.1.0/network OR just use the vpn system as the default gateway to avoid routing problems...

Using brouting:

• Enable proxy_arp on the linux router: echo 1 > /proc/sys/net/ipv4/conf/proxy_arp
• Add the route of the subnet to eth0 if not happened automagically

• Add the route of a subnet of the local subnet to the tun device from openvpn.

  Lets say we're going to use the last 16 IP-addresses for the hosts on the vpn (192.168.1.240 - 192.168.1.255) that means we have a 28 bits subnet 192.168.1.240/28. Create the tun device static (openvpn --mktun) and then add the route for the vpn subnet to the device ip route add 192.168.1.240/28 dev tun0

After this, and after enabling ip forwarding and proxy arp the linux system will "broute" all requests from the local clients to the clients at the vpn end and vice versa.

And you have an layer 3 vpn (faster, less traffic) with layer 2 connectivity and fully transparent access to all systems.

Filtering and everything else can be done via iptables.

KR,

Gromit