nsm-ids-triage

NSM IDS Triage (read-only)

MCP Server

• Server: nsm-mcp (NetClaw-authored, spec 091)
• Tools: nsm_status, nsm_update_rules, nsm_alerts, nsm_analyze
• Engine: Suricata 8.0.6, pinned by image digest
• Input: a .pcap/.pcapng file already on disk. Nothing sniffs an interface.

The rule that matters most here

Zero alerts is not a clean result until you have checked the signature count.

Stock Suricata loads 0 signatures and reports 0 alerts, announcing it with two non-fatal warnings. Measured: 0 signatures on stock config versus 52,205 after nsm_update_rules. A detector that loaded nothing inspected nothing.

nsm_alerts attaches suricata_posture to every response for exactly this reason:

state	What it means	What you may say
ARMED	signatures loaded, detector ran	"no alerts matched the loaded ruleset"
INERT	0 signatures	"the detector was off" — never "the traffic is clean"
UNKNOWN	count seen, no ruleset file	treat with suspicion, re-run after nsm_update_rules

When posture is INERT, the tool replaces an empty alert list with an object carrying NOT_A_CLEAN_RESULT. That is deliberate: it cannot be read as a clean verdict by a caller that only looks at the alert field.

Workflow: triage a capture

1. nsm_status — is docker reachable, is a ruleset present, how old is it?
2. If no ruleset: nsm_update_rules, then continue. Do not proceed to conclusions on an INERT run — report that the detector was off and stop.
3. nsm_alerts with min_severity=2 — the alerts worth a human's attention first
4. nsm_alerts unfiltered — the full picture, noting truncated if set
5. For each alert that matters, pivot to the session with nsm-session-pivot using the src_ip/dest_ip/dest_port — an alert without its session context is a signature match, not an incident

Reading alerts honestly

• A signature match is not a compromise. ET Open contains policy and informational rules; category and severity matter. Say what matched, not what it implies.
• A ruleset age is part of the finding. A 30-day-old ruleset cannot alert on last week's signatures; nsm_status reports ruleset_age_days and the skill should quote it.
• Suricata alerts on malformed traffic too. SURICATA TCPv4 invalid checksum means the capture has bad checksums — usually NIC offloading, not an attack. It is also a signal that Zeek would discard those packets, so cross-check with nsm-session-pivot.
• truncated: true means you are looking at a page. Never present it as the total.

Important Rules

• No writes, no live capture. This analyses a file. Blocking traffic or changing a sensor is not available and must not be offered.
• Never report "0 alerts" without the posture — the tool will not let you, and neither should the summary you write.
• Record in GAIT — log every triage, including the signature count and ruleset age.

Integration with Other Skills

Skill	How They Work Together
nsm-session-pivot	Turn an alert into its full session and protocol context
packet-analysis	Drop to individual packet decode (tshark) for a specific alert
cml-packet-capture / gns3-packet-capture	Produce the capture this skill analyses
gait-session-tracking	Record all triage runs

Environment Variables

• NSM_HOME — analysis and ruleset directory (default ~/.openclaw/nsm)
• NSM_TIMEOUT — per-container timeout in seconds (default 600)