ssh_exec · MCP SSH Proxy MCP: Risk & Policy

WHAT IT DOES

What ssh_exec does on MCP SSH Proxy

AI agents invoke ssh_exec to trigger actions in MCP SSH Proxy. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why ssh_exec needs a policy

This tool executes arbitrary shell commands on remote SSH servers. Despite the human-in-the-loop approval mechanism, the tool itself is an Execute-category action — it runs shell commands whose effects are entirely argument-dependent and could range from benign reads to destructive operations.

From the tool's definition "Runs a shell command on one of the configured SSH servers" and "Returns stdout, stderr and the exit code"

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ssh_exec Rate-limited

ssh_exec stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "ssh_exec": {
      "limits": [
        {
          "counter": "ssh_exec_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches MCP SSH Proxy, so you can run agents against it safely.

FAQ

Questions about ssh_exec

What does the ssh_exec tool do? +

Runs a shell command on one of the configured SSH servers. The user reviews and approves (or edits/rejects) the command in the SSH Proxy desktop app before it runs. Returns stdout, stderr and the exit code. Use ssh_list_hosts to discover valid host names. It is categorised as a Execute tool in the MCP SSH Proxy MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on ssh_exec? +

Register the MCP SSH Proxy MCP server in PolicyLayer and add a rule for ssh_exec: 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 MCP SSH Proxy. Nothing to install.

What risk level is ssh_exec? +

ssh_exec is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit ssh_exec? +

Yes. Add a rate_limit block to the ssh_exec 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 ssh_exec completely? +

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

ssh_exec is provided by the MCP SSH Proxy MCP server (quinbook/mcpsshproxy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.