TNT

TNT's Not Tunnel - A lightweight terminal chat server written in C

Features

• ✨ Vim-style operations - INSERT/NORMAL/COMMAND modes
• 📜 Message history - Browse with j/k keys
• 🕐 Full timestamps - Year-month-day hour:minute with timezone
• 📖 Bilingual help - Press ? for Chinese/English help
• 🌏 UTF-8 support - Full support for Chinese, Japanese, Korean
• 📦 Single binary - Lightweight executable
• 🔒 SSH access - Secure encrypted connections
• 🖥️ Auto terminal detection - Adapts to your terminal size
• 💾 Message persistence - All messages saved to log file
• ⚡ Low resource usage - Minimal memory and CPU

Building

Dependencies:

• libssh (required for SSH support)

Install dependencies:

# On macOS
brew install libssh

# On Ubuntu/Debian
sudo apt-get install libssh-dev

# On Fedora/RHEL
sudo dnf install libssh-devel

Build:

make

For debug build:

make debug

Installation

Quick install (recommended):

curl -sSL https://raw.githubusercontent.com/m1ngsama/TNT/main/install.sh | sh

Or download from releases

See DEPLOYMENT.md for production setup.

Running

./tnt

Connect from another terminal:

ssh -p 2222 localhost

The server will prompt for a password (any password is accepted) and then ask for your username.

Usage

Operating Modes

• INSERT - Type and send messages (default)
• NORMAL - Browse message history
• COMMAND - Execute commands

Keyboard Shortcuts

INSERT Mode

• ESC - Enter NORMAL mode
• Enter - Send message
• Backspace - Delete character
• Ctrl+C - Exit

NORMAL Mode

• i - Return to INSERT mode
• : - Enter COMMAND mode
• j - Scroll down (older messages)
• k - Scroll up (newer messages)
• g - Jump to top
• G - Jump to bottom
• ? - Show help
• Ctrl+C - Exit

COMMAND Mode

• Enter - Execute command
• ESC - Cancel, return to NORMAL
• Backspace - Delete character

Available Commands

• list, users, who - Show online users
• help, commands - Show available commands
• clear, cls - Clear command output

Architecture

• Network: Multi-threaded SSH server using libssh
• TUI: ANSI escape sequences with automatic terminal size detection
• Storage: Append-only log file
• Concurrency: pthread + rwlock
• Security: Encrypted SSH connections with host key authentication

Configuration

Set port via environment variable:

PORT=3333 ./tnt

Technical Details

• Written in C11
• POSIX-compliant
• Thread-safe operations
• Proper UTF-8 handling for CJK characters
• Box-drawing characters for UI
• SSH protocol with PTY support for terminal size detection
• Dynamic window resize handling

Development

make debug        # Build with debug symbols
make asan         # Build with AddressSanitizer
make check        # Run static analysis
./test_basic.sh   # Run basic tests
./test_stress.sh  # Run stress test

See HACKING for development details.

Security

• Encrypted connections: All traffic is encrypted via SSH
• Host key authentication: RSA host key generated on first run
• Password authentication: Currently accepts any password (customize for production)
• Host key persistence: Stored in host_key file
• No plaintext: Unlike telnet, all data is encrypted in transit

License

MIT License - see LICENSE file