lpd / lpr - Line Printer Daemon protocol / Line Printer Remote protocol
The Line Printer Daemon protocol / Line Printer Remote protocol (or LPD, LPR) is a platform-independent printing protocol that runs over TCP / IP to send print jobs to remote printers. The technology was originally developed for BSD UNIX and has since become the de facto cross-platform printing protocol. The LPD protocol specification is documented in RFC 1179.
LPD protocol uses TCP port 515. A request begins with a byte containing the request code, followed by the arguments to the request, and is terminated by an ASCII LF character.
An LPD printer is identified by the IP address of the server and the queue name on that machine. Many different queue names may exist in one LPD server, with each queue having unique settings.
When printing job through LPR, there are two parts to each print job: the data file (the data to be printed) and the control file (instructions that describe the data file and specify what to do with the data file).
When a file is printed through LPR, the computer spools the print job to disk and generates the data file. It then sends the data file and control file to the IP address specified in the LPR desktop printer. Since there may be more than one queue at the destination IP address, the name of the queue is sent at the very beginning to identify the intended queue.
If the target is a printer, the printer prints the job. If the target is a print server, it may do some additional processing (for example, security checking) and then forward the job to the next target in the path which is usually the printer.
LPD protocol uses TCP port 515. A request begins with a byte containing the request code, followed by the arguments to the request, and is terminated by an ASCII LF character.
An LPD printer is identified by the IP address of the server and the queue name on that machine. Many different queue names may exist in one LPD server, with each queue having unique settings.
When printing job through LPR, there are two parts to each print job: the data file (the data to be printed) and the control file (instructions that describe the data file and specify what to do with the data file).
When a file is printed through LPR, the computer spools the print job to disk and generates the data file. It then sends the data file and control file to the IP address specified in the LPR desktop printer. Since there may be more than one queue at the destination IP address, the name of the queue is sent at the very beginning to identify the intended queue.
If the target is a printer, the printer prints the job. If the target is a print server, it may do some additional processing (for example, security checking) and then forward the job to the next target in the path which is usually the printer.
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