AI agents invoke telnet to trigger actions in IT Tools MCP Server. 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.
This tool initiates an outbound TCP connection to an arbitrary host and port, which is an external network operation. It 'executes' a network probe rather than merely reading local data. Misuse could enable port scanning, SSRF-style attacks, or probing internal network services. Severity is medium because it does not directly modify data but can be used to map or probe internal/external infrastructure.
From the tool's definition Test TCP connectivity to a host and port
Documented attack patterns abuse exactly the kind of access telnet gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and IT Tools MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for telnet:
{
"version": "1",
"default": "deny",
"tools": {
"telnet": {
"limits": [
{
"counter": "telnet_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}telnet 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.
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Test TCP connectivity to a host and port. It is categorised as a Execute tool in the IT Tools MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the IT Tools MCP Server MCP server in PolicyLayer and add a rule for telnet: 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 IT Tools MCP Server. Nothing to install.
telnet is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the telnet 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.
Set action: deny in the PolicyLayer policy for telnet. 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.
telnet is provided by the IT Tools MCP Server MCP server (wrenchpilot/it-tools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from IT Tools MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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119 IT Tools MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.