iscsi_extent_create

THE RISK

Medium Risk

Why iscsi_extent_create needs a policy

Creating an iSCSI extent is a write operation that establishes a new storage resource on the TrueNAS system. While reversible (the extent can be deleted), it represents a significant modification to the storage infrastructure that could impact system capacity allocation and connected clients.

From the tool's definition Tool name 'iscsi_extent_create' and description 'Create an iSCSI extent (LUN)' indicate creation of a new iSCSI logical unit number, which is a data storage resource.

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

POLICY

How to control iscsi_extent_create

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_extent_create:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "iscsi_extent_create": {
      "limits": [
        {
          "counter": "iscsi_extent_create_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

iscsi_extent_create stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. 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.

LIMIT THIS TOOL →

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EXPLORE

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All 279 Truenas tools →

Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about iscsi_extent_create

What does the iscsi_extent_create tool do? +

Create an iSCSI extent (LUN). It is categorised as a Write tool in the Truenas MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on iscsi_extent_create? +

Register the Truenas MCP server in PolicyLayer and add a rule for iscsi_extent_create: 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_extent_create? +

iscsi_extent_create is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit iscsi_extent_create? +

Yes. Add a rate_limit block to the iscsi_extent_create 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_extent_create completely? +

Set action: deny in the PolicyLayer policy for iscsi_extent_create. 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_extent_create? +

iscsi_extent_create 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.

CHECK YOUR STACK →