ICS/SCADA › Module 4 › Lesson 1
Modbus Named
Modbus literacy names register model, master/slave roles, and defensive monitoring — not exploit cookbooks on YOUR $OT_LAB — defensive OT literacy only; no real-plant attacks, unauthorized OT scans, or exploit cookbooks.
Visual · t38_modbus_named
Modbus Named literacy. $OT_LAB only. Original Cyberlium.
Opening
Modbus is everywhere and often unauthenticated — literacy teaches defender visibility, not write tutorials against real RTUs.
Modbus TCP/RTU moves register reads and writes between masters and slaves with minimal built-in security. Cyberlium names function codes, port 502 literacy, and segmentation expectations — never step-by-step Modbus attack scripts against live plants. Cyberlium Topic 38 practices on $OT_LAB — YOUR fictional OT templates, zone diagrams, and labeled checklists under $HOME/cyberlium-lab/t38-ot/ no real-plant attacks, unauthorized OT scans, or exploit cookbooks. Next: DNP3 OPC UA.
1. What Modbus Named covers (named)
Modbus literacy: coils/discrete inputs, holding/input registers, master/slave topology, serial vs TCP. Defenders monitor unexpected writes, new masters, and flat network exposure. On $OT_LAB, document literacy rows on fictional LAB-OT-001 — never live plant IPs, credentials, or exploit steps.
Write Modbus literacy row — role, typical port, monitoring point. No exploit payloads or live device targets. On $OT_LAB, document literacy rows on fictional LAB-OT-001 — never live plant IPs, credentials, or exploit steps.
Command guide
Try these commands — What Modbus Named covers (named)
═══ TOOLS & WEBSITES ═══ Browse / read these (authorized learning only — stay in YOUR lab / program scope)
CISA ICS protocols — https://www.cisa.gov/topics/industrial-control-systems NIST SP 800-82 — https://csrc.nist.gov/publications/detail/sp/800-82/rev-3/final
═══ INSTALL ═══
Linux (Debian/Ubuntu):
Command — copy this
sudo apt install curl
macOS: Built-in
Windows: Built-in (PowerShell: Invoke-WebRequest)
═══ LINUX / macOS ═══
Command — copy this
export OT_LAB=${OT_LAB:-$HOME/cyberlium-lab/t38-ot}
cat > "$OT_LAB/notes/modbus-named.txt" <<'EOF'
Modbus literacy — NAMED (DEFENSIVE ONLY):
Roles: master/slave; TCP port 502 literacy
Registers: coils, discrete inputs, holding/input registers
Risks: often no auth on legacy deployments
Defense: segmentation, allowlists, passive monitoring
NEVER: exploit cookbooks or write tutorials against live RTUs/plants
EOFCommand — copy this
grep -E 'Modbus|Defense|NEVER' "$OT_LAB/notes/modbus-named.txt" curl -sS https://www.cisa.gov/topics/industrial-control-systems | head -5
Primary tools to practice this lesson: grep, curl. Reference sites: CISA ICS protocols (https://www.cisa.gov/topics/industrial-control-systems); NIST SP 800-82 (https://csrc.nist.gov/publications/detail/sp/800-82/rev-3/final). Run every command in the box — install first, then the usage lines — only on YOUR lab / program scope.
2. Why Modbus Named matters for defenders
Flat IT/OT networks expose Modbus to ransomware lateral movement. Conduits and allowlists reduce unsolicited master traffic. On $OT_LAB, document literacy rows on fictional LAB-OT-001 — never live plant IPs, credentials, or exploit steps.
Students draft Modbus defender cards on lab notes. Production segmentation follows IEC 62443 zone design. On $OT_LAB, document literacy rows on fictional LAB-OT-001 — never live plant IPs, credentials, or exploit steps.
3. $OT_LAB boundary
Forbidden: Modbus fuzz/write cookbooks against real RTUs or water plants. Allowed: Modbus named literacy card on fictional LAB-OT-001. On $OT_LAB, document literacy rows on fictional LAB-OT-001 — never live plant IPs, credentials, or exploit steps.
Ship: Modbus literacy card. Next: DNP3 OPC UA.
4. What you ship: modbus named card for $OT_LAB
Modbus literacy names register model, master/slave roles, and defensive monitoring — not exploit cookbooks. $OT_LAB named. NEVER real-plant attack steps. chmod 600.
5. What you record before the next lesson
Date (UTC). Modbus Named card. $OT_LAB named. File t38-m04-l01-modbus-named.txt chmod 600.
6. Wrong vs right: plant attacks vs YOUR OT lab sims
Worked failure — same MSF word, opposite target. Right never needs a café Wi-Fi or classmate laptop.
Wrong
Follow tutorial writing Modbus coils on live substation RTU.
Right
Write modbus named card for YOUR $OT_LAB. Next: DNP3 OPC UA.
Mission: document Modbus Named on YOUR OT lab
1) Name literacy rows on $OT_LAB. 2) Write NEVER list (no real-plant attacks, unauthorized OT scans, or exploit cookbooks). 3) chmod 600. Never scan or exploit real industrial networks.
Stuck? Ask Cyberlium AI Mentor
Ask Mentor: literacy on $OT_LAB — not attack recipes against live plants.
Knowledge Check
APPLY: Modbus Named on Cyberlium means:
Multiple choice
Knowledge Check
APPLY: True or False: Topic 38 includes ICS attack cookbooks against real plants.
True or False
Knowledge Check
APPLY: Modbus Named literacy on Cyberlium uses:
Multiple choice