Maintenance
Backup Verification Drills
Turn “we have backups” into provable restores with checksums, scopes, and honest time estimates.
3 weeks · 15 lab hours540,000 KRW
Programs catalog
Filter by how your shift actually feels
Each listing shows honest duration text and KRW tuition bands. Enrollment still flows through humans so we can match rack time to your team’s quiet hours.
13 programs match
Networking
firewalld and Network Namespaces Intro
Draw zones that match reality, test rules safely, and peek into namespaces without losing your place.
3 weeks · 16 lab hours560,000 KRW
Monitoring
Incident Coordination for On-call Rotations
Run bridges without talking over each other, time-box investigations, and hand off cleanly at shift end.
5 weeks · 24 lab hours1,560,000 KRW
Maintenance
journald Rotation Lab
Tune retention, ship logs safely, and stop disks from filling because nobody owns the logging budget.
2 weeks · 10 lab hours420,000 KRW
Linux Admin
Linux Service Boot Camp
Rebuild confidence restarting units, reading unit files, and tracing failed dependencies on Enterprise Linux hosts.
5 weeks · 32 lab hours890,000 KRW
Networking
Nginx Upstream Health Checks
Design upstream blocks that fail visibly, tune probes honestly, and document behavior under partial outages.
3 weeks · 17 lab hours670,000 KRW
Linux Admin
Package Pinning on Enterprise Linux
Hold versions without freezing security, and document exceptions when vendors insist on bleeding edges.
2 weeks · 10 lab hours410,000 KRW
Linux Admin
Postfix Queue Triage Lab
Quiet noisy queues, trace deferred reasons, and communicate impact without promising magic delivery fixes.
2 weeks · 11 lab hours430,000 KRW
Monitoring
Prometheus Exporters for Bare Metal
Instrument noisy hosts without melting CPUs, label metrics honestly, and keep dashboards readable.
4 weeks · 22 lab hours980,000 KRW
Maintenance
RAID Concepts and Disk Checks
Read mdadm noise, interpret SMART triage, and know when to stop poking and escalate hardware.
4 weeks · 20 lab hours720,000 KRW
Security Basics
SSH Hardening and Key Lifecycle
Rotate keys without locking yourself out, layer bastion patterns, and document access for audits.
3 weeks · 18 lab hours610,000 KRW
Linux Admin
systemd Timers for Maintenance
Replace mystery cron lines with timers you can explain, monitor, and silence when they misbehave.
2 weeks · 12 lab hours480,000 KRW
Security Basics
User ACL Patterns with Extended Attributes
Layer POSIX ACLs without hiding ownership problems, and document decisions future-you will understand.
2 weeks · 9 lab hours390,000 KRW