Packet Path Labs

Mission Index

220 browser-simulated labs · staged for review

220labs 24free 4tracks ~232htotal est. time
Review build: all progression locks are bypassed (?review=1) so every lab is testable. Not for public use.

Network Penetration Testing

Think like an attacker: enumerate, exploit, pivot, and write the report.

50 labs 6 free

Stealing Data and Staying In

Steal sensitive data without setting off alarms, and plant backdoors that survive reboots - while learning why these are the hardest attacks for defenders to find.

Enterprise Network Engineer

Keep the business online: observe, hypothesize, isolate, fix, verify, document.

60 labs 6 free

Hyperscaler Network Engineer

Operate at cloud scale: Clos fabrics, ECMP, BGP, and bad config pushes.

60 labs 6 free

Senior Network Engineer

Design and defend how traffic flows: write the designs, set routing policy, automate repairs, and be the escalation point for the operations teams.

HFT Low-Latency Network Engineer

Chase microseconds: measure, hypothesize, isolate, tune, verify, document.

50 labs 6 free
L3 · AdvancedMicroburst Hunt~50 minhft-microburst-hunt L3 · AdvancedPTP Sync Lost~55 minhft-ptp-sync-lost L4 · ExpertTick-to-Trade~70 minhft-tick-to-trade L4 · ExpertThe Two-Microsecond Mystery~75 minhft-two-microsecond-mystery L3 · AdvancedBuffer Tuning~50 minhft-buffer-tuning L4 · ExpertFPGA vs Kernel Bypass~80 minhft-fpga-vs-kernelbypass L3 · AdvancedMulticast Gap~55 minhft-multicast-gap L2 · IntermediateClock Drift~40 minhft-clock-drift L2 · IntermediateCable Length Audit~40 minhft-cable-length-audit L3 · AdvancedCross-Connect Failover~55 minhft-cross-connect-failover L4 · ExpertJitter Root Cause~70 minhft-jitter-root-cause L5 · CapstoneCAPSTONETrading Day Chaos~150 minhft-trading-day-chaos L1 · BeginnerFREEWhat Is Latency, Really?~25 minhft-what-is-latency L1 · BeginnerFREEReading a Tick-to-Trade Waterfall~25 minhft-tick-waterfall L1 · BeginnerFREEKernel Bypass in Plain English~25 minhft-kernel-bypass-basics L1 · BeginnerFREEMeet PTP: Clocks That Agree~30 minhft-ptp-basics L1 · BeginnerFREECut-Through vs Store-and-Forward~30 minhft-cut-through-basics L1 · BeginnerFREESpotting a Gap in the Feed~30 minhft-feed-handler-basics L2 · IntermediateLatency Budget Math~35 minhft-latency-budget-math L2 · IntermediatePath Segment Drill~40 minhft-path-segment-drill L2 · IntermediateTimestamps You Can Trust~40 minhft-pcap-timestamps L2 · IntermediateDR Rehearsal: Four Minutes to Fail Over~40 minhft-dr-runbook L2 · IntermediateArista EOS: Low-Latency Mode~35 minhft-eos-latency-mode L2 · IntermediateIGMP Snooping: Stop the Shouting~40 minhft-igmp-snooping L2 · IntermediateIRQ Affinity: Interrupts on the Wrong CPU~40 minhft-irq-affinity L2 · IntermediatePTP Profile Audit~40 minhft-ptp-profile-audit L3 · AdvancedColo Rack Layout: Meters Are Money~50 minhft-colo-rack-layout L3 · AdvancedSlow Market Open: Find the Flood~55 minhft-slow-market-open L3 · AdvancedExchange Certification: Speak the Protocol~50 minhft-cert-conformance L3 · AdvancedArista LANZ: Catch the Invisible Congestion~50 minhft-eos-lanz L3 · AdvancedLayer-1 Cutover at Light Speed~60 minhft-layer1-cutover L3 · AdvancedBuild the Timestamping Kernel Module~55 minhft-kmod-build L3 · AdvancedDPDK Bringup: Hugepages and Port Binding~50 minhft-dpdk-bringup L3 · AdvancedNUMA Tuning: Keep the App Near Its NIC~50 minhft-numa-tuning L3 · AdvancedThe Session That Flaps on the Dot~55 minhft-session-flap L4 · ExpertOpenOnload: Tuning the User-Space Stack~60 minhft-onload-profile-tune L4 · ExpertSyncE Holdover: When GPS Dies~60 minhft-synce-holdover L4 · ExpertOne-Way Delay: The Fiber Lies Asymmetrically~60 minhft-one-way-delay L4 · ExpertProve the Backup Path Is Really Disjoint~70 minhft-colo-redundancy L4 · ExpertCharacterize the Holdover Oscillator~60 minhft-holdover-characterize L4 · ExpertXDP: Filter Before the Kernel Wakes~65 minhft-xdp-filter L4 · ExpertDebug the Crashing Kernel Module~65 minhft-kmod-debug L4 · ExpertDrop-Copy Audit: Trust but Verify~60 minhft-drop-copy-audit L5 · Expert+SmartNIC Offload: Flow Steering in Silicon~80 minhft-smartnic-offload L5 · Expert+Sev-1 Postmortem: The Worst Outage This Year~90 minhft-sev1-postmortem L5 · Expert+L1 vs L2: Timed to the Nanosecond~80 minhft-l1-vs-l2-latency L5 · Expert+DPDK Pipeline: Unclog the Slowest Stage~85 minhft-dpdk-pipeline-tune L5 · Expert+XDP vs DPDK: The Benchmark Duel~85 minhft-xdp-vs-dpdk L6 · CapstoneCAPSTONEZero-Downtime Exchange Migration~150 minhft-zero-downtime-migration L6 · CapstoneCAPSTONEDR Failover Certification: Sign Your Name~180 minhft-dr-failover-cert