Internet Access
Sandboxes have full internet access by default.
Overview
All Lelantos sandboxes have unrestricted outbound internet access by default. Sandboxes can make HTTP requests, connect to databases, pull packages, clone repositories, and access any external service.
DNS Configuration
DNS is configured for you. All pre-built templates and all custom templates resolve hostnames out of the box — no Dockerfile workarounds required.
FROM ubuntu:22.04
RUN apt-get update && apt-get install -y curlDon't add RUN echo "nameserver 8.8.8.8" > /etc/resolv.conf to your Dockerfile. Older Lelantos docs recommended this as a workaround, but Docker BuildKit (the default builder) mounts /etc/resolv.conf read-only during the build, so the line now fails with Read-only file system. If you copied this line from a tutorial, remove it — DNS works without it.
Network Details
- Outbound: All TCP/UDP traffic is allowed to any destination.
- Inbound: Sandboxes are accessible via the proxy URL
{port}-{sandboxID}.lelantos.ai. The proxy routes traffic from the internet to the specified port inside the sandbox. - No firewall restrictions: There are no egress firewall rules applied to sandboxes. If your use case requires network isolation, terminate the sandbox when the task is complete.
Accessing Sandbox Services
If your sandbox runs an HTTP server or other network service, you can access it through the sandbox proxy:
https://{port}-{sandboxID}.lelantos.aiFor example, a web server running on port 3000 in sandbox sbx_abc123 would be reachable at:
https://3000-sbx_abc123.lelantos.ai