Normally, OpenVPN Access Server requires a functioning DHCP server on the remote network for its Microsoft Windows clients when it is operating in Layer 2 Ethernet Bridging mode. However, this may not be feasible when your remote network does/can not have a DHCP server due to security concerns. In addition, Linux and Mac clients will only function when Access Server is configured using static IP addressing under the Layer 2 operating mode.
In order for you to configure OpenVPN Access Server to use static IP addressing mode, all of these requirements must be met:
To configure Access Server in static IP addressing mode, go to the Advanced VPN section of the Web Admin UI.
Under Additional OpenVPN Config Directives (Advanced) and inside the Server Config Directives box, enter the follow lines using the syntax below:
server-bridge <gw ip> <subnet mask> <start IP range> <end IP range>
push dhcp-option DOMAIN <DNS search suffix> - optional
push dhcp-option DNS <dns srv 1> - optional, only if you want to use remote DNS servers.
push dhcp-option DNS <dns srv 2> - optional, only if you want to use remote DNS servers.
push dhcp-option DNS <dns srv ...> - optional, only if you want to use remote DNS servers.
Note: DNS options are only recognized in Windows and Mac (Access Server specific) clients. Linux support for DNS options are not implemented at this time.
For example, if you have a remote network with the following characteristics:
Reserved VPN IP Range: 192.168.1.100 - 192.168.1.130
Subnet Mask: 255.255.255.0
Gateway IP Address: 192.168.1.1
DNS search suffix: somecompany.com
DNS Server 1: 220.127.116.11
DNS Server 2: 18.104.22.168
DNS Server 3: 22.214.171.124
You would enter the following in the aforementioned text box:
server-bridge 192.168.1.1 255.255.255.0 192.168.1.100 192.168.1.130
push dhcp-option DOMAIN somecompany.com
push dhcp-option DNS 126.96.36.199
push dhcp-option DNS 188.8.131.52
push dhcp-option DNS 184.108.40.206
Afterwards, click Save Settings and Update Running Server to apply your changes.