build(cloud): add firewall config

Signed-off-by: David Karlsson <[email protected]>

Author: dvdksn

content/manuals/build-cloud/setup.md

@@ -70,6 +70,14 @@ The builder has native support for the `linux/amd64` and `linux/arm64`
 architectures. This gives you a high-performance build cluster for building
 multi-platform images natively.
 
+## Firewall configuration
+
+To use Docker Build Cloud behind a firewall, ensure that your firewall allows
+traffic to the following addresses:
+
+- https://build-cloud.docker.com
+- 3.211.38.21
+
 ## What's next
 
 - See [Building with Docker Build Cloud](usage.md) for examples on how to use Docker Build Cloud.