AI agents use pfsense_update_services_dhcp_server_custom_option to create or update resources in Pfsense — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Pfsense environment.
The tool modifies DHCP server custom options, which is a reversible configuration change (Write category). Severity is high because DHCP server configuration changes can disrupt network services, affect client connectivity, and potentially redirect traffic or inject malicious configurations (custom options could include DNS redirection, gateway changes, etc.).
From the tool's definition Tool name contains 'update' and 'dhcp_server', indicating modification of DHCP server configuration. The server description confirms this tool is part of a pfSense firewall management suite with 'full control' via REST API v2, covering 'services' among other…
Attacks that exploit this kind of access
pfsense_update_services_dhcp_server_custom_option. It is categorised as a Write tool in the Pfsense MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Pfsense MCP server in PolicyLayer and add a rule for pfsense_update_services_dhcp_server_custom_option: 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 Pfsense. Nothing to install.
pfsense_update_services_dhcp_server_custom_option is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the pfsense_update_services_dhcp_server_custom_option 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 pfsense_update_services_dhcp_server_custom_option. 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.
pfsense_update_services_dhcp_server_custom_option is provided by the Pfsense MCP server (abl030/pfsense-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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