Firewalls

This help document describes the ports that CUPS uses so that firewall administrators can allow traffic used for printing.

Table 1 lists the ports that are used for IPP printer sharing via CUPS.

Table 1: Ports Used for IPP Printer Sharing
(Destination) Port	TCP/UDP	Direction	Description
53 (DNS)	TCP/UDP	OUT	Domain Name System lookups and service registrations.
631 (IPP/IPPS)	TCP	IN	Internet Printing Protocol requests and responses (print jobs, status monitoring, etc.)
5353 (mDNS)	UDP	IN+OUT	Multicast DNS lookups and service registrations.

Table 2 lists the ports that are used for SMB (Windows) printer sharing, typically via the Samba software.

Table 2: Ports Used for SMB Printer Sharing
(Destination) Port(s)	TCP/UDP	Direction	Description
137 (WINS)	UDP	IN+OUT	Windows Internet Naming Service (name lookup for SMB printing).
139 (SMB)	TCP	IN	Windows SMB printing.
445 (SMBDS)	TCP	IN+OUT	Windows SMB Domain Server (authenticated SMB printing).

Ports Used for Network Printers

Table 3 lists the ports for outgoing network traffic that are used for network printers.

Notes:
DNS and mDNS are used for all printing protocols except SMB.
SNMP is used to provide status and supply level information for AppSocket and LPD printers.

Table 3: Outgoing Ports Used for Network Printers
(Destination) Port(s)	TCP/UDP	Description
53 (DNS)	TCP/UDP	Domain Name System lookups.
137 (WINS)	UDP	Windows Internet Naming Service (name lookup for SMB printing).
139 (SMB)	TCP	Windows SMB printing.
161 (SNMP)	UDP	SNMP browsing (broadcast) and status monitoring (directed to printer IP address).
443 (IPPS)	TCP	Internet Printing Protocol requests and responses (print jobs, status monitoring, etc.)
445 (SMBDS)	TCP	Windows SMB Domain Server (authenticated SMB printing).
515 (LPD)	TCP	Line Printer Daemon (LPD/lpr) print job submission and status monitoring.
631 (IPP/IPPS)	TCP	Internet Printing Protocol requests and responses (print jobs, status monitoring, etc.)
5353 (mDNS)	UDP	Multicast DNS lookups.
9100-9102	TCP	Raw print data stream (AppSocket/JetDirect).