ssh_spawn · Mcpx MCP: Risk & Policy

WHAT IT DOES

What ssh_spawn does on Mcpx

AI agents invoke ssh_spawn to trigger actions in Mcpx. 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_spawn needs a policy

Despite the empty description, the tool name 'ssh_spawn' strongly implies spawning an SSH session or process. In context of a shell/SSH mastery server with sibling tools like shell_exec and shell_spawn, this tool almost certainly initiates an interactive SSH session, enabling arbitrary remote command execution on external systems.

From the tool's definition Tool name 'ssh_spawn' on a server described as enabling 'command execution, interactive sessions, file transfer, and port forwarding with auditing and policy controls'; sibling tools include shell_exec, shell_script, shell_spawn — all execution-oriented.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ssh_spawn Rate-limited

ssh_spawn 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_spawn": {
      "limits": [
        {
          "counter": "ssh_spawn_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 Mcpx, so you can run agents against it safely.

FAQ

Questions about ssh_spawn

What does the ssh_spawn tool do? +

ssh_spawn. It is categorised as a Execute tool in the Mcpx 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_spawn? +

Register the Mcpx MCP server in PolicyLayer and add a rule for ssh_spawn: 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 Mcpx. Nothing to install.

What risk level is ssh_spawn? +

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

Can I rate-limit ssh_spawn? +

Yes. Add a rate_limit block to the ssh_spawn 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_spawn completely? +

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

ssh_spawn is provided by the Mcpx MCP server (rmednitzer/relay-shell). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.