bups - Brother USB Print Server

A network print server for Brother PT (P-Touch) and QL label printers. Exposes USB-connected printers over the network via TCP port 9100, with mDNS discovery and SNMP status reporting.

Features

• TCP Print Server (port 9100) - Raw print data forwarding with bidirectional status
• mDNS Advertisement - Automatic printer discovery via Bonjour/Avahi (re-advertises on reconnect)
• SNMP Responder (port 161) - Brother-compatible status queries
• Auto-Reconnect - Configurable health monitoring and reconnection
• Daemon Mode - PID file, syslog support, graceful shutdown (SIGTERM/SIGINT)
• Pure Rust USB - Uses nusb (no libusb dependency)
• Static Binary - Builds for musl targets (Alpine, OpenWrt, embedded Linux)

Supported Printers

PT Series (TZe Tape)

QL Series (Labels)

Installation

Homebrew (macOS)

brew tap metaneutrons/tap
brew install bups

Cargo

cargo install bups

AUR (Arch Linux)

yay -S bups

From Source

cargo build --release
./target/release/bups --help

For a fully static musl binary (portable to Alpine, OpenWrt, etc.):

rustup target add x86_64-unknown-linux-musl
cargo build --release --target x86_64-unknown-linux-musl

Usage

bups - the print server for USB-based label printers

Usage: bups [OPTIONS]

Options:
  -p, --port <PORT>                  TCP port for print data [default: 9100]
      --snmp-port <SNMP_PORT>        SNMP port for status queries [default: 161]
  -d, --debug                        Enable debug logging
  -b, --bind <BIND>                  Bind address [default: [::]]
      --model <MODEL>                Filter by model name (e.g. PT-E550W)
      --serial <SERIAL>              Filter by serial number
      --hostname <HOSTNAME>          Hostname for mDNS advertisement
  -l, --list                         List connected printers and exit
      --reconnect-interval <SECS>    Reconnect check interval [default: 30]
      --max-reconnects <N>           Max reconnect attempts (0 = infinite) [default: 0]
      --pid-file <PATH>              Write PID to file (for daemon mode)
      --syslog                       Log to syslog instead of stderr
  -h, --help                         Print help

Examples

List connected printers:

bups -l

Start server with debug logging:

bups -d

Start server for specific printer:

bups --model PT-E550W --serial 000E9Z931020

Custom mDNS hostname:

bups --hostname MyLabelPrinter

TCP Commands

Connect via netcat to send commands:

echo "STATUS" | nc localhost 9100
echo "HELP" | nc localhost 9100

Running as a Daemon

bups runs in foreground by default (modern systemd style). No --daemon flag needed.

With systemd (recommended)

Create /etc/systemd/system/bups.service:

[Unit]
Description=Brother USB Print Server
After=network.target

[Service]
Type=simple
ExecStart=/usr/local/bin/bups --syslog
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

Then:

sudo systemctl daemon-reload
sudo systemctl enable --now bups

Testing / Development

bups -d  # Debug logging to stderr

With traditional init (SysV, OpenRC)

bups --pid-file /var/run/bups.pid --syslog &

For proper daemonization with traditional init, use a process supervisor or wrapper like start-stop-daemon:

start-stop-daemon --start --background --make-pidfile \
  --pidfile /var/run/bups.pid --exec /usr/local/bin/bups -- --syslog

The daemon will:

• Start even if no printer is connected (waits for USB hotplug events)
• Automatically reconnect when printer is unplugged/replugged (instant via USB hotplug)
• Re-advertise via mDNS when printer changes
• Clean up PID file on shutdown
• Handle SIGTERM/SIGINT (Ctrl+C) gracefully

Architecture

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│  Print Client   │────▶│      bups       │────▶│  Brother USB    │
│  (macOS/Linux)  │◀────│   TCP:9100      │◀────│    Printer      │
└─────────────────┘     │   SNMP:161      │     └─────────────────┘
                        │   mDNS          │
        ┌───────────────┴─────────────────┴──────────────┐
        │                                                │
   ┌────▼────┐    ┌──────────┐    ┌──────────┐    ┌──────▼──────┐
   │   TCP   │    │   SNMP   │    │   mDNS   │    │   Health    │
   │ Server  │    │Responder │    │ Advertise│    │   Check     │
   └─────────┘    └──────────┘    └──────────┘    └─────────────┘

Dependencies

• nusb - Pure Rust USB library
• tokio - Async runtime
• mdns-sd - mDNS/DNS-SD
• rasn-snmp - SNMP protocol
• clap - CLI argument parsing
• tracing - Structured logging
• syslog-tracing - Syslog support (Unix)

Credits

This project was heavily inspired by and based on the excellent work of Ryan Kurte on rust-ptouch. The USB communication protocol, device definitions, and status parsing are derived from that project.

License

GPL-3.0-or-later

Copyright (C) 2026 Fabian Schmieder

See Also

• rust-ptouch - Brother P-Touch Raster Driver
• Brother Raster Command Reference