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.
  

Learn more about network ports in xneelo Cloud

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.

Attaching an interface in the Cloud dashboard adds the network device to the instance, but your operating system may still need to be configured before the connection works.

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.

On some instances, especially existing running instances, the new interface may not become active automatically inside the operating system. 

Check that the new virtual network card (vNIC) is detected and configured correctly.

A newly attached interface may not become active automatically inside the operating system.

The exact steps depend on your operating system, image, and network setup. Configuration inside the guest operating system is managed by you, and falls outside our scope of support.

After attaching an interface, check the following inside your operating system:

• The new virtual network card (vNIC) is detected
• The interface is enabled and active
• If DHCP is enabled on the subnet, the interface is configured to obtain an IP address automatically
• If DHCP is disabled on the subnet, the interface has a valid static IP configuration
• The correct routes are in place, especially if the instance has multiple interfaces
• Local firewall rules on the operating system are not blocking the required traffic
• DNS is configured if you need name resolution on that network.

For example, this may require configuration in tools such as Netplan on Ubuntu or NetworkManager on AlmaLinux.

Tip: If the interface exists in the Cloud dashboard but has no working connectivity inside the instance, first check whether the operating system has brought the interface up and assigned it an IP address.

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:

1. Confirm the interface and network

• The interface is attached to the correct network
• The network and subnet are configured correctly
• The interface has a fixed IP address assigned (from the subnet)

2. Check subnet settings

• DHCP is enabled if you expect the interface to receive an IP automatically
• If DHCP is disabled, ensure you have configured a valid static IP inside the operating system
• The subnet CIDR range and gateway IP are valid

3. Verify security

• The security groups on the interface allow the required traffic
• Any firewall rules inside the operating system allow the same traffic

4. Check the operating system configuration

• The operating system detects the new interface (vNIC)
• The interface is enabled and has an IP address assigned
• If DHCP is enabled, the interface is set to obtain an IP automatically
• If DHCP is disabled, the interface has a correct static IP, subnet mask, and gateway

5. Review routing (for multiple interfaces)

• If your instance has multiple interfaces, confirm traffic is using the correct interface
• Incorrect routing can cause traffic to leave via the wrong network or fail entirely

Tip: If the interface appears correctly in the Cloud dashboard but has no connectivity, the issue is often within the operating system configuration rather than the Cloud network.