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On a remote private network there are two servers -- a file server and a database server (these are both Win machines, in case it matters).

The file server has its own fairly robust authentication mechanisms, and allows me to connect directly from a remote location.

The database server uses a simple username and password, so to prevent unauthorized access, it's locked down to the local network -- external traffic is blocked.

To access the database server, I'm using the OpenVPN client on Windows to connect to a VPN server on the private network.

By default, OpenVPN routes all network packets destined for the remote network on which the VPN server resides, through the VPN. Unfortunately, accessing the file server through the VPN is extremely slow!

Question:

How can I configure the OpenVPN client to ONLY route traffic through the VPN that is destined for a single, specific IP address -- namely the database server??

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5 Answers 5

Reset to default
128

The correct configuration for OpenVpn is:

route-nopull 
route 192.168.0.0 255.255.255.0

These entries belong in your .ovpn file and will direct all 192.168.0.* subnet traffic through the VPN.

For one IP only (192.168.0.1):

route-nopull 
route 192.168.0.1 255.255.255.255

BTW: route-nopull means "don't pull routes from the server"

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  • 2
    +1. This is exactly what I needed. I am using ovpn clients on my linux and hence you answer just saved me. Thanks.
    – slayedbylucifer
    Commented May 30, 2014 at 8:33
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    Can i just route a website to vpn?For example just www.facebook.com
    – Nicola Peluchetti
    Commented Oct 28, 2014 at 22:15
  • 4
    is it possible to use dns name instead of ip address ?
    – Michael
    Commented Dec 25, 2014 at 22:30
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    But routes has a 3rd argument which is the gateway, what should I put there ?
    – Neji Soltani
    Commented Jun 2, 2019 at 13:16
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    for me the problem with route-nopull is that it prevents the server from giving me its DNS server. I do want the VPN dns, but I do not want to route all ips... digging.
    – hwjp
    Commented Mar 8, 2021 at 10:57
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Goals

  • Use the plain internet connection for all internet traffic by default, even when the VPN is connected.
  • Route traffic to one specific IP address through the VPN.

Steps

  1. Press Win + R and execute ncpa.cpl.

  2. Right-click the VPN connection and go to Properties → Networking.

  3. Select Internet Protocol Version 4 and go to Properties → Advanced....

  4. Uncheck Use default gateway on remote network and click OK.

  5. (optional) Repeat the previous steps for Internet Protocol Version 6.

  6. (Re)connect to your VPN.

  7. Open a command prompt and execute route print -4.

  8. Spot the VPN's interface in the Interface list and its gateway in the Active Routes.

    On my machine, I have:

    Interface List
 32...........................Super Free VPN

[...]

Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0         On-link        10.6.6.127     31
         10.0.0.0        255.0.0.0        10.88.1.1      10.88.1.102     31

    Here, the VPN's gateway is 10.88.1.1, since its the gateway for the 10.xxx.xxx.xxx block.

  9. Add a persistant route that will be appended to the active routes whenever there's a connection to the VPN:

    route -p add 23.22.135.169 10.88.1.1 if 32

    In this example, 23.22.135.169 is the IP of whatismyip.org, 10.88.1.1 is the gateway's IP and 32 the number of the interface.

  10. (optional) Repeat the previous steps for route print -6.

  11. Test the setup.

    If everything worked out, whatismyip.org and www.whatismyip.cx will display different IPs now.

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  • 3
    Surely there's a simpler way?
    – Brian Lacy
    Commented Aug 7, 2012 at 14:56
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    Do you know how to achieve this under Linux (Ubuntu)?
    – Elin Y.
    Commented Mar 26, 2014 at 11:49
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    @ЕлинЙ. if you're using Network Manager just select "Use this connection only for resources on this network".
    – leif.gruenwoldt
    Commented Nov 8, 2014 at 2:09
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    +1 ... but could golf this?
    – Olivier Dulac
    Commented May 26, 2016 at 17:50
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To your OpenVPN client config, add a line like:

route The.IP.To.Go 255.255.255.255

(Where The.IP.To.Go is the IP you wish to route through the VPN)

This instructs OpenVPN to create the entry in your OS's routing table.

Alternatively, the OpenVPN server could be made to "push" this routing configuration down to clients, by adding to the server config:

push "route The.IP.To.Go 255.255.255.255"

EDIT: One thing I missed addressing--the default forwarding of all traffic... It could either be disabled on the server, or clients can elect to ignore "pushed" directives (so our second option "pushing" the route would not work) via:

route-nopull
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  • As the question is written, this is probably the best answer - the question explicitly asks for a client config change. However, if there's only one user (or all have the same rules) and they're in charge of both client and server I'd just change the routing in the "server.conf" on the OpenVPN server to add the desired individual routes in (the example conf file has example routes in it).
    – SomeoneElse
    Commented Feb 24, 2023 at 21:02
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In response to the comments asking for an easy linux / networkmanager friendly solution to customizing what gets routed over OpenVPN, here is a GUI friendly way to set it up. This answer is, as far as I can tell, just the GUI version of Thomas's answer.

Screenshot of network manager showing where to click

Step 1: select your VPN configuration

Step 2: go over to the relevant tab (either IPv4 or IPv6)

Step 3: Click the "Routes..." button in the bottom right

Step 4: Add your desired route (in this case it is redirecting all traffic from 192.168.0.* through the VPN

Step 5: check the "use only for resources on this connection" checkbox so that connecting to the VPN doesn't change your default gateway settings to route all traffic through the VPN.

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  • 1
    It also works by leaving the column "Gateway" empty (then it defaults to 0.0.0.0)
    – domids
    Commented Jan 13, 2022 at 9:06
-1 
iptables -A PREROUTING -t mangle -i <LAN_interface> \
-d <remote_network>/<remote_netmask> -j ROUTE --gw <openvpn_host_ip>
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    Please explain what this command does. Just one command without explanation is not that useful. Also check the formatting of your post—all the <brackets> are not visible if they're not marked as code.
    – slhck
    Commented Feb 13, 2015 at 10:44
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    The question is about configuring the Windows OpenVPN client side of things; this is a Linux server-side configuration that doesn't apply.
    – Jim Stewart
    Commented Dec 19, 2019 at 8:06
  • @JimStewart The answer needs improvement, but it does appear to be for a Linux openvpn client.
    – Otheus
    Commented Dec 8, 2023 at 22:28

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