Labor
Linux & OS hardening: Debian / Ubuntu administration, CIS Benchmark hardening, patching
Containers: Docker, Dockerfile best practices, basic container security
Vulnerability & open source: JFrog Xray (or Trivy / Grype), reading CVE reports, open-source licence
approval (OSSA)
Networking: TCP/IP, VLANs, firewall rules (iptables / nftables), Docker networking
Security research: following security news, CVE feeds and vendor advisories; summarising findings
clearly
Scripting & documentation: Bash / basic Python; clear records and checklists
Good to have: IEC 62443 basics, AppArmor, Secure Boot / TPM, MQTT with TLS; LFCS / RHCSA,
Security+