Azure Network : Prevent subnet to subnet communication

Question

I have the following subnets

1. Subnet_1 = 10.2.3.0
2. Subnet_1 = 10.2.4.0

I want to prevent subnet to subnet communication. As far as I see, it can be done using the Network Security Group. However I am not sure about the required change.

Answer 1

I tried to reproduce the same in my environment to prevent communication between 2 Subnet

I have created 2 subnets in my Vnet, like below.

Subnet 1: Prod-Subnet (10.0.1.0/24)

Subnet 2: default (10.0.0.0/24)

In order to prevent communication between both the VNet, you need to create an inbound and outbound rule in same NSG group, like below.

I have created 2 virtual machines and attached above subnets to 2 virtual machines, like below.

Prod-subnet attached to VM1 Default Subnet attached to VM2

Create inbound and outbound rule in Network Security Group to block the communicatioin ,like below.

Inbound Rule:

Source IP: 10.0.0.9/24
Source Port: * ( for all)
Destination IP: 10.0.1.0/24
Destination Port: *( for all)
Service: custom

(Note: If you want block particular service and port, mention the port details and protocol type)

Outbound Rule:

Source IP: 10.0.1.0/24
Source Port: * ( for all)
Destination IP: 10.0.0.0/24
Destination Port: *( for all)
Service: custom

Tested communication and its getting denied from the subnets.

VM 1 Result

VM 2 Result