iscsi_targetextent_list

THE RISK

Low Risk

Why iscsi_targetextent_list needs a policy

This tool retrieves and queries existing iSCSI target-to-extent mapping configurations from TrueNAS SCALE without performing any side effects, modifications, or destructive operations. It is a pure read operation that gathers information about storage configuration state.

From the tool's definition Tool name contains 'list' and description explicitly states 'List all iSCSI target-to-extent mappings' with no modification, deletion, or execution capability.

Documented attack patterns abuse exactly the kind of access iscsi_targetextent_list gives an agent:

POLICY

How to control iscsi_targetextent_list

PolicyLayer is an MCP gateway — it sits between your AI agents and Truenas, and nothing reaches the server without passing your rules. This is the rule we recommend for iscsi_targetextent_list:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "iscsi_targetextent_list": {}
  }
}

iscsi_targetextent_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Truenas — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about iscsi_targetextent_list

What does the iscsi_targetextent_list tool do? +

List all iSCSI target-to-extent mappings. It is categorised as a Read tool in the Truenas MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on iscsi_targetextent_list? +

Register the Truenas MCP server in PolicyLayer and add a rule for iscsi_targetextent_list: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Truenas. Nothing to install.

What risk level is iscsi_targetextent_list? +

iscsi_targetextent_list is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit iscsi_targetextent_list? +

Yes. Add a rate_limit block to the iscsi_targetextent_list rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block iscsi_targetextent_list completely? +

Set action: deny in the PolicyLayer policy for iscsi_targetextent_list. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides iscsi_targetextent_list? +

iscsi_targetextent_list is provided by the Truenas MCP server (spranab/truenas-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Truenas tool call.

Start from Truenas, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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