telnet_wrapper

A telnet server that wraps any terminal application, exposing it to telnet clients with proper protocol support.

Features

• Wraps any terminal application and exposes it via telnet
• Telnet protocol support using libtelnet-rs
• Window size negotiation (NAWS) - automatically resizes the PTY when the client window changes
• Character-by-character input (no line buffering)
• Supports multiple concurrent clients
• Configurable initial terminal size
• Configurable listening port

Installation

From crates.io

cargo install telnet_wrapper

From source

git clone https://github.com/justpresident/telnet_wrapper
cd telnet_wrapper
cargo build --release

Usage

telnet_wrapper [OPTIONS] <APP_COMMAND> [APP_ARGS]...

Arguments

Argument	Description
<APP_COMMAND>	The application command to run within the PTY
[APP_ARGS]...	Arguments to pass to the application command

Options

Option	Default	Description
--port <PORT>	23	Port to listen on
--rows <ROWS>	24	Initial number of rows for the PTY
--cols <COLS>	80	Initial number of columns for the PTY
-h, --help		Print help
-V, --version		Print version

Examples

Expose htop on port 2323

telnet_wrapper --port 2323 /usr/bin/htop

Then connect:

telnet localhost 2323

Run a shell accessible via telnet

telnet_wrapper --port 2323 /bin/bash

Run vim with a specific file

telnet_wrapper --port 2323 /usr/bin/vim /tmp/test.txt

Custom terminal size

telnet_wrapper --port 2323 --rows 40 --cols 120 /usr/bin/htop

Telnet Protocol Support

This wrapper implements the following telnet options:

Option	Description
ECHO	Server-side echo (enables character mode)
SGA	Suppress Go Ahead (required for character mode)
NAWS	Negotiate About Window Size (dynamic terminal resizing)
LINEMODE	Disabled to ensure character-by-character input

Tips

• To close a telnet connection, press Ctrl+] and then type q or press Ctrl+D
• Ports below 1024 require root/administrator privileges. Use higher port numbers when possible
• Don't expose terminals/shells/file editors on publicly accessible addresses! This can be easily exploited to take control over your server. Only expose services within trusted local network or securely-designed applications that do not expose a risk of damaging your system.
• The TERM environment variable is set to xterm-256color for the wrapped application

License

MIT License - see LICENSE for details.