Tcpsh

MCP server for tcpsh — the interactive TCP connection manager.

MCP server exposing 13 tools for interactive TCP connection management: open listeners, interact with sessions, forward ports, proxy traffic, and run local commands — all from any MCP-compatible AI host (Claude Desktop, VS Code Copilot, etc.).

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Installation

This server is installed on demand from GitHub — no npm registry required.

Add to your MCP host configuration:

{
  "mcpServers": {
    "tcpsh": {
      "command": "npx",
      "args": ["-y", "github:nchgroup/tcpsh-mcp"]
    }
  }
}

npx -y github:nchgroup/tcpsh-mcp clones the repository, runs npm install, and executes the bin entry — no manual setup required.

Requirements

• Node.js ≥ 18.0.0
• Internet access on first run (GitHub clone + npm install)

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Tools

#	Tool	Description
1	open_port	Open a TCP listener
2	close_port	Close a listener and its sessions
3	list_ports	List open ports and session counts
4	list_sessions	List active sessions with traffic counters
5	send_to_session	Send data to a TCP session
6	read_from_session	Read buffered data from a TCP session
7	kill_session	Terminate a session (FIN or RST)
8	session_info	Detailed info about a session
9	add_forward	Start a transparent TCP forward
10	add_proxy	Start a TCP proxy with traffic logging
11	list_forwards	List active forwards and proxies
12	remove_forward	Stop a forward or proxy
13	exec_local	Run a shell command on the local machine

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Tool Reference

open_port

port   (number, required)  TCP port to listen on
host   (string, optional)  Bind address or interface name — default: 0.0.0.0

host accepts an IP address, a network interface name, or can be omitted:

open_port(4444)                  # bind 0.0.0.0:4444
open_port(4444, "127.0.0.1")     # loopback only
open_port(4444, "tun0")          # resolves tun0 → its IPv4 address
open_port(443,  "eth0")          # resolves eth0 → its IPv4 address

In standalone mode (no TCPSH_SERVER) the interface is resolved locally via os.networkInterfaces().
In remote mode the interface name is sent as-is to the tcpsh server, which resolves it there.

close_port

port   (number, required)  Port to close (closes all its sessions too)

send_to_session

port   (number, required)  Port the session belongs to
idx    (number, optional)  Session index, 1-based — default: 1
data   (string, required)  Raw data to send (no newline added automatically)

read_from_session

port   (number, required)  Port the session belongs to
idx    (number, optional)  Session index — default: 1

Drains the internal RX buffer. Call again to receive subsequent data.

kill_session

port   (number, required)  Port the session belongs to
idx    (number, optional)  Session index — default: 1
force  (boolean, optional) true = RST (immediate), false = FIN (graceful) — default: false

add_forward

local_port   (number, required)  Local port to listen on
remote_host  (string, required)  Destination host
remote_port  (number, required)  Destination port

add_proxy

local_port   (number, required)  Local port to listen on
remote_host  (string, required)  Destination host
remote_port  (number, required)  Destination port
log_file     (string, optional)  Path to write hex traffic log

exec_local

command  (string, required)  Shell command executed via sh -c

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Example Prompts

Open a reverse shell catcher:

"Open port 4444 and wait for a connection"

Read shell output:

"Read the output from the session on port 4444"

Send a command to a session:

"Send the command 'id\n' to port 4444"

Set up port forwarding:

"Forward local port 8080 to 10.0.0.1:80"

Intercept HTTP traffic:

"Start a proxy on port 8080 pointing to 10.0.0.1:80, log to /tmp/http.log"

Run a local network scan:

"Run nmap -sV localhost and return the output"

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Remote Mode

tcpsh-mcp can delegate all TCP management to a remote tcpsh server instead of running a local in-process manager. This is useful when:

• the AIhost is sandboxed and cannot open TCP ports directly
• you want state to persist even if the MCP process restarts
• multiple AI sessions should share the same network state

Prerequisites

Start a tcpsh server on the target machine:

tcpsh -server 0.0.0.0:9000

The token printed at startup encrypts all traffic with ChaCha20-Poly1305.

Enable remote mode

Pass two environment variables when starting the MCP server. Example MCP host configuration:

{
  "mcpServers": {
    "tcpsh-remote": {
      "command": "npx",
      "args": ["-y", "github:nchgroup/tcpsh-mcp"],
      "env": {
        "TCPSH_SERVER": "127.0.0.1:9000",
        "TCPSH_TOKEN": "aBcDeFgHiJkLmNoPqRsTuVwXyZ012345"
      }
    }
  }
}

Or on the command line:

TCPSH_SERVER=127.0.0.1:9000 TCPSH_TOKEN=<TOKEN> node src/index.js

What works remotely

Tool	Remote support
open_port … remove_forward (12 tools)	✅ Delegated to tcpsh server
exec_local	⚠️ Always runs locally (on the MCP server host)

When neither TCPSH_SERVER nor TCPSH_TOKEN is set, tcpsh-mcp falls back to its built-in in-process TCP manager (default behaviour).

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Architecture

tcpsh-mcp/
├── package.json            bin entry + @modelcontextprotocol/sdk dep
└── src/
    ├── index.js            McpServer + StdioServerTransport + tool registration
    │                       (selects TcpManager or RemoteTcpManager at startup)
    ├── tcp-manager.js      Local TCP state: listeners, sessions, RX buffers, forwards, proxies
    ├── remote-manager.js   Remote mode: encrypted ChaCha20-Poly1305 frames over TCP
    └── tools.js            13 tool definitions (inputSchema + handlers)

• Transport: stdio — compatible with all MCP hosts
• State: in-process (default) or on the remote tcpsh server (remote mode)
• RX buffer: received data is buffered per session and drained on read_from_session
• SDK: @modelcontextprotocol/sdk v1.x (stable)

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Manual Testing

Send raw JSON-RPC to the server's stdin:

# Start the server
node src/index.js

# In another terminal / via pipe:
printf '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}\n{"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}\n' \
  | node src/index.js

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Related Projects

• tcpsh — Go implementation (REPL binary) — the project this MCP wraps
• tcpsh-mcp — this repository

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License

MIT