From UntangleWiki

Contents 1 About Interfaces 2 Interface Configuration 3 Adding and Removing Interfaces 4 Swapping Interfaces

About Interfaces

Interfaces refer to individual network cards in your box - one NIC is one interface. By default, the first three interfaces are named:

• External: The External interface is your primary connection. All external-facing services such as OpenVPN will connect using the External interface.
• Internal: The Internal interface is connected to your LAN, probably to your core switch.
• DMZ: If there is a third interface detected during install, it will be named DMZ. It's just a name; the interface does not function in any special way.

Any additional interfaces will be named eth3, eth4, etc. If you're in bridge mode, the External interface will be pointed towards the Internet and your Internal interface will be bridged to External.

From left to right on the menu you can see the Interface Name, Configuration Type, Switching Arrow, Physical Interface including connection light, and MAC Address.

Interface Configuration

The table below contains a list of all options; only the applicable options will be displayed depending on your selections for Config Type and is WAN Interface.

Setting	Description
Config Type	This entry controls the type of interface: Use Static if you have a static IP. Use Dynamic if you have a dynamic IP. Use Bridge if you'd like to bridge the interface to another interface. You can use PPPoE if your line requires it, but we highly recommend finding out from your ISP if your modem can handle the PPPoE login so you can use Static here. PPPoE connections do not work with Multi-WAN features and it's generally better to use Static if possible.
is WAN Interface	Use this checkbox if the interface should be a WAN connection (e.g. pointed towards the Internet).
Primary IP and Netmask	The IP Untangle should use on the interface - for example 203.0.113.1/28 or 10.0.0.1/24.
IP Address Aliases	These are additional IPs Untangle should hold on that interface. For multiple public IPs on WAN interfaces, the netmask should (in most cases) match the mask of your primary IP. If you're entering the alias so Untangle will route traffic for VLANs or other networks, make sure to give Untangle a real, unused IP (e.g. not x.x.x.0).
NAT Policies	When using a non-WAN interface, these control how machines are NATed to the WAN interface. The "0.0.0.0/0 auto" policy will NAT everything out of your primary IP. Like many lists in Untangle this works from the top down, so make sure the "0.0.0.0/0 auto" policy is at the bottom or it will take precedence. See 1:1 NAT for more info.
Default Gateway	The gateway to use for this interface.
Primary/Secondary DNS Server	The DNS servers Untangle should use to resolve queries - we highly recommend using your ISP's servers.
Override IP Address/Netmask/Gateway/DNS	When using a Dynamic interface, you can use these to override the information pulled from the upstream DHCP server.
Username/Password	When using a PPPoE interface, this is your Username/Password. As noted above, we recommend having your modem handle the login so you can use a Static interface type if possible.
PPPoE Optional Parameters	When using a PPPoE interface, these are any optional parameters that the Untangle needs to use. As noted above, we recommend having your modem handle the login so you can use a Static interface type if possible.
Bridge to	When using a Bridge interface, this is the interface you want to bridge the current interface to. You'll want to bridge other interfaces to External, not the other way around.
MTU	The Maximum Transmission Unit of your network. Leave this blank (auto) unless you have a good reason not to.
Ethernet Media	Controls the speed of the interface's NIC. Leave this set to Auto unless you're having duplexing issues. If you are having issues, we recommend verifying both sides are set to Auto before trying to change it.

Adding and Removing Interfaces

To add or remove interfaces from the box, simply power it down, add or remove cards as needed, then reboot. Once that's done, go to Config > Networking and click Refresh Interfaces to finish detection, then you're free to use the interfaces as you'd like.

Swapping Interfaces

If you want to change which card is used for which interface, first take note of the current MAC addresses of each card. From there, simply click and hold the four-cornered arrow on one interface and release it over another - they will turn orange to indicate a change has been made. Verify the MAC addresses are set up as you want them, then hit Save.