August Season: Cutting the Wire
Three boxes, three severed paths — DNS, firewall rules, and a route that was never supposed to disappear. Someone made sure nothing connected the way it should before they left. Trace each break, repair it properly, and recover what's waiting on the other side. All on sandboxes you fully control. Defensive practice only.
Networking · 3 challenges · Live now — ends 2026-08-31.
Play the CTF →DNS: The Parting Shot
The outgoing sysadmin broke internal name resolution on their way out — the resolver only points at a public nameserver now, and the hosts file has lost the one static record everything else depends on. Restore resolution properly, then go see what they left behind for the next person to find. You have full root on this isolated, offline box.
Write-up publishes when the season closes.
Firewall: The Rule They Slipped In
Someone with access gave themselves a way back in before things got locked down: one extra accept rule, buried in an otherwise normal-looking nftables config, dressed up with a comment that could pass for legitimate at a glance. Find it, remove it cleanly without touching the rules that belong, and recover what they left as a receipt.
Write-up publishes when the season closes.
Reach the Evidence Server
Before they left, whoever had access cut off every path to the evidence collector on the response subnet: the name doesn't resolve, the route to that subnet is gone, and the one firewall rule that mattered got overridden by a DROP. None of it looks deliberate at first glance — that's the point. Rebuild the path layer by layer and recover what's waiting once you're actually connected.
Write-up publishes when the season closes.