Networks

In a Nutshell

Each bwCloud-OS instance automatically receives a public IP address, valid for its entire lifetime (until deletion). Instances are also assigned a persistent FQDN based on their UUID and region. Domain hosting is not provided, but you can point your own domain to the instance’s FQDN using a CNAME record. SSL certificates can be obtained via Let’s Encrypt using tools like Certbot.

Networks & IP-addresses

Will my instance receive a public IP?

Yes. By default, every instance launched using the standard method in bwCloud-OS is automatically assigned a publicly accessible IP address.

Each region in bwCloud-OS has its own set of IP address ranges, which may differ from one another. You can find the current public IP ranges for each region here.

How long does an IP remain assigned to my instance?

The public IP address(es) assigned to your instance remains associated with it for the entire lifetime of the instance — even if you stop (shut down) the instance.

The IP is only released when the instance is deleted (terminated). After termination, the IP is returned to the regional pool and may be reassigned to another instance in the region.

Are Floating IPs also available for instances?

Currently only in certain regions, such as Freiburg. However, Floating IPs are planned for all regions after the next major software upgrade in 2026.

See the Floating IP Guide for detailed setup instructions.

Hostnames and Domains

Does bwCloud-OS also assign hostnames?

Yes. Every running instance in bwCloud-OS is automatically assigned a generic hostname (FQDN). This allows the instance to be reached via a persistent network identifier, even if its public IP address changes. This FQDN is valid for the lifetime of the instance.

Format of the Instance's FQDN

• The UUID of the instance
• The region abbreviation (e.g., ma for Mannheim)
• The domain suffix: .bw-cloud-instance.org

Example:

If your instance UUID is caffee-4242-2323-caffee and it runs in Mannheim (ma), the FQDN will be:

caffee-4242-2323-caffee.ma.bw-cloud-instance.org

Retrieval: From inside the instance, the FQDN can be determined by:

REGION="ma"
FQDN="$(cat /var/lib/cloud/data/instance-id).${REGION}.bw-cloud-instance.org"

The FQDN can also be found in the Dashboard, under the instance details.

Can I get a domain via bwCloud-OS?

No, bwCloud-OS does not provide custom domain hosting. However, you can use your own domain — either through your home institution or an external domain provider — to point to your instance.

Some options are described below.

How can I point a domain to an instance?

You can point a domain to your instance in two main ways:

🔹 CNAME to the instance FQDN

The instance’s FQDN is based on its UUID and region. Since the UUID is persistent for the instance's lifetime (even if the instance is stopped and started again), you can safely set a CNAME record like:

myvm.example.org → uuid.region.bw-cloud-instance.org

🔹 Dynamic DNS

Alternatively, you can configure a Dynamic DNS setup where your VM updates its IP in a third-party DNS service — especially if you don’t have your own domain, or your use case involves frequently changing or multiple IPs.

Can I get a certificate from bwCloud-OS?

No, bwCloud-OS does not provide certificates. However, you can obtain certificates directly from public providers like Let’s Encrypt using tools such as Certbot, which you install and run on your instance.