discover-printers-bonjour

Discover Printers via Bonjour

Scan the local network for printers advertising via mDNS (Bonjour/Avahi). Return a table of discovered devices.

When to use

• User wants to find printers on the LAN by name/model
• Printer not yet registered in CUPS
• Bonjour/mDNS is available on the network
• Pre-flight before running add-printer

Inputs to gather

• None (uses local avahi-daemon and network broadcast)

Procedure

1. Check avahi-daemon. Verify the service is running:

   systemctl is-active avahi-daemon
   

   If inactive, output:

   avahi-daemon is not running.
   To start it: sudo systemctl start avahi-daemon
   To enable on boot: sudo systemctl enable avahi-daemon
   

   Stop here until the user confirms the service is running.

2. Browse for printers. Run with a 5-second timeout:

   timeout 5 avahi-browse -rt _ipp._tcp _ipps._tcp _printer._tcp 2>/dev/null || true
   

   Parse lines matching = (result/resolved) into a table.

3. Extract fields. For each result line, extract (using regex or field split):

   • name (service name, before @)
   • hostname (host field, or derive from full address.local record)
   • IPv4 (address field, IPv4 only)
   • port (port number)
   • model (from ty= TXT field, e.g. "HP LaserJet Pro M404n")
   • rp (resource path, e.g. /ipp/print, from TXT field)

4. Format as table:

   Name                 Host              IPv4            Port  Model                    Path
   Office-HP            printer01.local   192.168.1.50    631   HP LaserJet Pro M404n    /ipp/print
   ...
   

5. Handle empty result. If no printers found after 5 seconds:

   No printers found via Bonjour.
   Possible reasons:
   - Printer does not support mDNS/Bonjour.
   - Printer is on a different VLAN or network segment.
   - Bonjour advertisement is disabled on the printer.
   
   Try: discover-printers-arp (ARP-based network scan)
   

Output / side effects

• Printer table to stdout.
• No local files modified.
• Read-only; no side effects.

Safety / constraints

• Read-only discovery; safe to run repeatedly.
• mDNS broadcast may not cross VLANs; if printers are segregated, try discover-printers-arp.