A Windows Server 2022 host already shares several office printers with Windows 10 clients over SMB. A group of legacy UNIX workstations will now send print jobs to the same server, but the workstations only support the LPR/LPD protocol specified in RFC 1179 and cannot be re-configured. A stateful firewall between the UNIX subnet and the data-center blocks all unsolicited traffic.
To allow the UNIX hosts to print with the least change to their configuration, which Windows print-service role and inbound TCP port should the administrator enable on the server?
Install the Internet Printing role service and open TCP 631.
Install the Print Server role service and open TCP 445.
Install Remote Desktop Services and open TCP 3389 for printer redirection.
Install the LPD Service role service and open TCP 515.
LPR/LPD clients submit print jobs to a Line Printer Daemon (LPD) listener that, by convention, waits on TCP port 515. Windows Server provides this listener by adding the LPD Service role service under Print and Document Services. Enabling that role and permitting inbound connections on port 515 lets UNIX systems print without changing their software.
Internet Printing exposes printers with the Internet Printing Protocol (IPP) on TCP 631, which the UNIX workstations do not speak.
The core Print Server role relies on SMB file-and-printer sharing over TCP 445; SMB is not compatible with LPR/LPD-only clients.
Remote Desktop printer redirection travels inside RDP sessions on TCP 3389 and neither presents a print queue nor satisfies LPR/LPD requests.
Therefore, activating LPD Service plus TCP 515 is the only combination that meets the requirement.