Start packet capture on a link.
AI agents invoke gns3_start_capture to trigger actions in GNS3 Network Simulator 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.
Starting a packet capture is an Execute action because it triggers an external operation on the GNS3 simulation infrastructure. While non-destructive, it actively controls and monitors the simulation state. It does not merely read existing data (Read category) but rather initiates a capture process.
From the tool's definition Tool name: gns3_start_capture; description: 'Start packet capture on a link.' This initiates an external operation (packet capture) whose effects depend on which link is targeted and what network traffic occurs.
Documented attack patterns abuse exactly the kind of access gns3_start_capture gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and GNS3 Network Simulator MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for gns3_start_capture:
{
"version": "1",
"default": "deny",
"tools": {
"gns3_start_capture": {
"limits": [
{
"counter": "gns3_start_capture_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}gns3_start_capture 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.
Free to start. No card required.
Start packet capture on a link. It is categorised as a Execute tool in the GNS3 Network Simulator MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the GNS3 Network Simulator MCP Server MCP server in PolicyLayer and add a rule for gns3_start_capture: 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 GNS3 Network Simulator MCP Server. Nothing to install.
gns3_start_capture 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 gns3_start_capture 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 gns3_start_capture. 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.
gns3_start_capture is provided by the GNS3 Network Simulator MCP Server MCP server (wael-rd/gns3-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from GNS3 Network Simulator MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
42 GNS3 Network Simulator MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.