Network Address Translation (NATs)

Adding an Interface

NATs are scoped to an interface. Add an interface from the Actions menu.

Inside NATs

An inside NAT defines how a local device IP address translates into a virtual network address. For instance, a local device may have a local IP address of 192.168.1.100, but you may want it to appear to other devices or applications on the virtual network as IP address 10.0.20.100. Or you may want an entire block of local IP addresses to show up on the virtual network as a different block. You can do this translation with an inside NATs. Inside NATs also control what local devices can participate on the virtual network. If a local device does not have an inside NAT configured that includes its IP address, it can’t access or be accessed by other devices on the network. Inside NATs require the following information:

Outside NATs

By default, when a device on the local network of a node receives traffic from a remote device on the network, the remote device IP address will be the IP address that was entered in the local CIDR block for the remote node’s inside NAT entry for the remote device. For instance, if the remote device was mapped to network address 10.0.100.1, then its traffic on the local network will appear to come from IP address 10.0.100.1. However, due to the local network configuration, there may be some situations where it is desirable to translate remote network addresses before egressing onto the local network. For example, on a local network of 192.168.0.0/16, a user may want the remote device’s virtual network IP of 10.0.100.1 to be translated to 192.168.50.5 so that it fits better into the local network setup. This kind of translation can be achieved by adding outside nats. To add an outside NAT you must enter the following information:

There are situations where it may be desirable to make multiple remote devices masquerade as one local IP address. This can be achieved by defining an outside nat in which the network CIDR contains a larger address space than the local CIDR. For instance, an entry with network CIDR 10.0.1.0/24 and local CIDR 192.168.100.10 would make all remote devices with network IP addresses in 10.0.1.0/24 appear as IP address 192.168.100.10 on the local network. In this configuration port address translation (PAT) is used for the source port of connections.

NAT Hit Counter

To the right of each defined NAT is a “Hits” button. Clicking this button will display the number of times that NAT has been used since the node was last restarted/rebooted or the counter was reset. This is useful for troubleshooting NATs or to see if a configured NAT is still required.