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Relay Agent Reverse TCP Listener

This relay listener uses an existing agent to accept reversed connections. The selected (relay) agent, identified by its GUID, waits for an incoming connection on a specified port. When a new agent is executed, it will attempt to connect to this relay agent using one of its provided hosts. If successful, communication will be routed through the relay agent.

Plugin ID: shelldot.listener.relay-agent-reverse-tcp

Configuration Reference

The If omitted column describes hand-written JSON sent directly to the API. The plugin's named default example generates a random UUID and explicitly supplies host localhost, port 5555, and an empty Base64 handshake value. Replace the generated UUID with the UUID of the relay agent you intend to use.

Parameter Type Required If omitted Description
relayAgentGuid UUID string Yes Invalid UUID of the existing agent that will listen for connections.
hosts string[] Yes Invalid One or more valid hostnames or IP addresses for the relay agent.
port int Yes Invalid TCP port (1-65535) on which the relay agent will listen for incoming connections.
handshakeBytes Base64 string Yes Configuration serialization fails Bytes used for the initial handshake between the agents. Direct JSON must supply this field; use "" to disable the handshake.
startTime string No null Optional UTC start time if the listener should not start immediately (e.g. 2025-04-10T11:02:09Z).

Configuration Scenarios

Scenario 1 - Basic Relay Reverse TCP

A relay listener that routes traffic through an existing agent to reach a new agent on the internal network.

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{
  "relayAgentGuid": "de1b8bbe-3ba3-4d46-bb92-c2011515cea9",
  "hosts": ["192.168.32.135"],
  "port": 5555,
  "handshakeBytes": "QUFBQQ=="
}

Example (POST Request)

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POST /api/v1/listeners HTTP/1.1
Authorization: Bearer {JWT_TOKEN}
Content-Type: application/json

{
  "plugin": "shelldot.listener.relay-agent-reverse-tcp",
  "name": "my-relay-tcp-reverse-listener",
  "configuration": {
    "relayAgentGuid": "de1b8bbe-3ba3-4d46-bb92-c2011515cea9",
    "hosts": [
      "192.168.32.135"
    ],
    "port": 5555,
    "handshakeBytes": "QUFBQQ==",
    "startTime": "2023-04-10T11:02:09Z"
  }
}