Focused, hands-on DevOps and server-side problems with hints, feedback, and automated solution checks.
A container port published on a server's internal IP is still reachable from the external network. Learn how to restrict access with firewall rules without disrupting legitimate connections.
Play a security researcher: identify the hosts a black-box container keeps making encrypted HTTPS calls to, route them through a MITM proxy, fake the certificate, and see what the container sends over the network.
Learn how to reconfigure the Kubernetes cluster DNS domain by updating CoreDNS ConfigMap and kubelet configuration on all nodes, a critical skill for custom cluster networking and CKA exam preparation.
Harden a bastion host so only admins can get a shell on it, operators can open tunnels to arbitrary destinations, and developers can reach only the one internal service they actually need.
Prove your networking skills by mapping one network address to another without starting any additional processes.
The culmination of the Docker networking challenges series. Can you create a Docker-like bridge network from scratch and using nothing but basic Linux commands.
Prove your mastery of Linux and containers by connecting multiple network namespaces into a single network.
Learn a bunch of Linux networking tricks while trying to access an Nginx server running inside a container started with ctr and a bare containerd daemon.
