Network challengecore5 devicespar 5:00
The ACL that blocks the wrong person
An access list meant to keep a guest laptop off the server locked out a staff PC instead. Make the filter match the policy.
The ticket
"Security asked us to block the guest laptop from the server. Since the change, Staff can't reach the server — and the guest can." — helpdesk escalation
Your goal: Let the Staff PC reach the Server and keep the Guest laptop blocked.
No sign-up · the clock starts when you press Start
The network you're handed
- R1 — a router, the router filtering traffic to the server
- SW1 — a switch, the office access switch
- Staff — a pc, the staff PC that must reach the server
- Guest — a pc, the guest laptop that must be blocked
- Server — a server, the protected server
It is already cabled and configured, and something in it is wrong. Nothing on this page tells you what — find it the way an engineer would, with show commands, ping and ipconfig in the industry-standard CLI.
How it's scored
- The grader checks the real network, not your commands: the simulator runs the actual pings and reads the actual tables. It passes the moment every check holds.
- One star for fixing it, one for beating the par time of 5:00, one for using 12 commands or fewer.
- A quick fix that breaks something else doesn't count — the checks also watch what must stay working (or stay blocked).
- Your copy of the network is private to your browser. Share your score and a friend gets their own fresh copy.
Skills: ACLs · Traffic filtering · Troubleshooting
Stuck? The theory behind it
Next challenge: The desk that can't leave its LAN