Controlling the Selection of Internal, External and Management Interfaces

Sample Azure Template, provided by Ivanti , requests Azure fabric to create three Network Interfaces. While running this template, Azure fabric creates interfaces named eth0, eth1 and eth2 and attaches them to ICS Virtual Interface.

So, the question is, among eth0, eth1 and eth2 which network interface will become external, internal or management interface? Below table answers this question.

Interface Name	ICS Interface
eth0	internal interface
eth1	external interface
eth2	management interface

Then, question is how you can control the order of network interfaces named eth0, eth1 and eth2 created through Azure Template?. Azure supports two types of interfaces: primary and secondary. Only one primary interface can be present on a VM.

For more details of primary and secondary interface, see https://docs.microsoft.com/en-us/azure/virtual-network/virtual-network-network-interface-addresses.

The Ivanti Connect Secure Virtual Appliance is qualified with internal interface as primary and other two are secondary. In the following code snippet, three network interfaces get assigned to VM. These three NICs with ID “nic1”, “nic2” and “nic3” are internally mapped to ‘eth0’, ‘eth1’, and ‘eth2’ respectively.

1.    "networkProfile": { 

2.        "networkInterfaces": [{ 

3.            "id": “nic1”, 

4.            "properties": { 

5.                "primary": true 

6.            } 

7.        }, { 

8.            "id": “nic2”, 

9.            "properties": { 

10.                "primary": false 

11.            } 

12.        }, { 

13.            "id": “nic3”, 

14.            "properties": { 

15.                "primary": false 

16.            } 

17.        }] 

18.    }, 

ICS converts eth0 to int0, eth1 to ext0 and eth2 to mgmt0. This means, the network interface with ID nic1 will be internal interface, nic2 will be external interface and nic3 will be management interface.

The below table depicts this scenario well:

Interface Name	ICS Interface	Network ID
eth0	internal interface (int0)	nic1
eth1	external interface (ext0)	nic2
eth2	management interface (mgmt0)	nic3

Suppose if you make ‘nic2’ as primary, then the order may not be maintained, and it is difficult to predict which interface will become internal interface of ICS. As a best practice, always assign ‘primary’ to the first network interface which will become internal interface of ICS.