Interfaces on cloud instances

An interface is a virtual network card (vNIC) on your instance. It connects the instance to a specific network port, which provides it with a fixed IP address and applies any assigned security groups.

When you attach an interface to an instance, you are essentially plugging that instance into the network by binding it to a network port.

• Port: A connection point on the network.
• Instance interface (vNIC): Attaches to the port and links the instance to the network.

Every instance has a primary interface by default. You can add secondary interfaces to connect the instance to additional networks.

Using multiple interfaces allows you to:

• Separate public traffic from private traffic.
• Add a private connection to an existing public instance.
• Assign floating IPs for public internet access.
• Apply different security group rules to each interface.

Tip: Use private interfaces for internal traffic whenever possible. This is more secure than exposing services to the public network.

You can view all interfaces attached to an instance in the Cloud dashboard.

You’ll see details such as port name, fixed IP(s), and you can edit the network port settings and security groups.

See more on managing network ports.

STEPS

1. 1
   In the Cloud dashboard, go to Compute > Instances.
2. 2
   Select the Instance Name.
3. 3
   Select the Interfaces tab.
4. 4
   The list of Interfaces attached to the instance will be displayed.

You can add a secondary interface to connect an instance to another network. This will create a new port on the selected network.

You can also attach an instance to an existing port on one of your private networks.

STEPS

1. 1
   In the Cloud dashboard, go to Compute > Instances.
2. 2
   Find the instance you want to access.
3. 3
   In the Actions column, select the down ▼ button and Attach Interface.
4. 4
   Choose how to attach the interface.

To attach by network:

1. 1
   Select by Network (and IP address).
2. 2
   Choose the network you want to attach.
3. 3
   Optional: If you selected a private network, specify a fixed IP from the subnet.
4. 4
   Select Attach Interface to confirm.

To attach the interface to a port:

1. 1
   Select by Port.
2. 2
   Choose the existing port you want to attach.
3. 3
   Select Attach Interface to confirm.

Once you have attached a port, you can then configure the security groups if needed.

Note: Inside the operating system, you may need to configure the new NIC (for example, ensure it receives an IP via DHCP).

You can remove secondary interfaces that you no longer need. The primary interface cannot be detached.

Detaching an interface will immediately disconnect the instance from that network.

STEPS

1. 1
   In the Cloud dashboard, go to Compute > Instances.
2. 2
   Select the instance.
3. 3
   In the Actions column, select the down ▼ button and Detach Interface.
4. 4
   Select Detach Interface to confirm.

If your instance cannot connect over an interface, check the following:

• The interface is attached to the correct network.
• The operating system recognises the NIC (check IP configuration).
• The security groups on that interface allow the required traffic.