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TCP 631

ProtocolTCP
Port631
Labelsipp, Internet Printing Protocol

Synopsis

  • TCP port 631 is the default port for the Internet Printing Protocol (IPP).
  • CUPS (Common UNIX Printing System) on macOS and most Linux/BSD distributions listens on TCP 631 for IPP printing.
  • Many network printers (e.g., HP LaserJet, Epson WorkForce, Brother, Canon) expose an IPP service on TCP 631.
  • Apple AirPrint uses IPP over TCP 631; iOS/iPadOS/macOS print to AirPrint-capable printers via this port.
  • Android’s Mopria Print Service uses IPP on TCP 631 to communicate with compatible printers.
  • Windows (Internet Printing Client/Print Spooler) can connect to IPP printers over TCP 631.
  • Bonjour/ZeroConf advertises _ipp._tcp services that typically listen on port 631 on local networks.
  • NAS devices like Synology and QNAP often run CUPS/IPP on TCP 631 to share USB printers.
  • Security note: Exposed CUPS/IPP services on 631 have been targeted for unauthorized printing, info disclosure, and DoS, with attackers scanning for open 631 and leveraging unpatched CUPS vulnerabilities.

Observed activity

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