> For the complete documentation index, see [llms.txt](https://docs.up-network.ch/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.up-network.ch/documentation/en/guides/how-to-use-additional-ipv4-addresses-on-a-dedicated-server.md).

# Use additional IPv4 addresses on a dedicated server

An additional IPv4 address can be used on the host operating system or routed to a VM, container or virtual firewall. The delivery method determines its configuration.

## Find the network details

Before making any changes, note the primary address, additional IP addresses, mask, gateway and routing mode provided for the server. Also ask for the port’s MAC rules and any anti-spoofing constraints.

An address published for another machine, an invented MAC address or a gateway chosen from an example are not suitable for your service.

## Routed delivery

In routed mode, the host receives traffic for the additional IP addresses and then forwards it to the internal systems. It acts as a router for these guests. The VMs use the intended addressing plan and internal gateway; they do not connect directly to the external switch.

When the port allows only one MAC address, a bridge exposing the VMs’ MAC addresses can cause a block. Routing allows you to keep the host’s MAC address on the physical link.

The host’s forwarding, routes and firewall must allow the exchanges. NAT is not inherently required for a routed public IP address; its use depends on your architecture.

## An address used on the host

Add the address with its mask and the routes specified in your delivery information, using the operating system’s network manager. Do not replace the primary address or create a second default route without an identified need.

## Verify

On Linux, check the state without changing the configuration:

```sh
ip -4 address show
ip -4 route show
sysctl net.ipv4.ip_forward
```

Then test external access to the service and the return path. If the settings or routed mode information are missing, [ask support for the network details](/documentation/en/guides/how-to-open-a-support-ticket.md) before deploying your VMs.

Updated on 3 October 2026. Reference: [UP-NETWORK dedicated servers](https://up-network.ch/services/dedicated-servers).