HP JetAdvantage Security Manager 10 Device E-LTU Manual de usuario descargar pdf (Pagina 76)

device. AirPrint security can be handled by disabling the protocol or securing the wireless network in

use. If AirPrint is not in use, disabling the protocol is recommended.

Line Printer Daemon/Line Printer

This protocol and set of programs is typically associated with line-printer spooling services on various

TCP/IP systems, such as Berkeley-based (BSD) UNIX, HP-UX, Linux, and Windows Server.

The Line Printer Daemon protocol/Line Printer Remote protocol (LPD/LPR) is a TCP/IP network print

and print server protocol, widely used by a multitude of operating systems and print services. Nearly

all operating systems now support at least the rudimentary LPD options in a service or daemon. The

original implementation of LPD was in the Berkeley Printing System (BPS) as part of the Berkeley

Software Distribution (BSD) UNIX operating system. In order to provide a complete printing system,

LPR/LPD is used with a printer driver that converts the data into the command format required by the

printer. The terms LPD and LPR are sometimes used synonymously. LPR was originally the name of the

software, and LPD was the name of the daemon that waited for server requests.

LPD/LPR is considered an essential offering and is available on all HP Jetdirect internal or external

print servers. When LPD/LPR is enabled, JetDirect listens on port 515 for print job requests. The

JetDirect LPD module maintains states so that it can detect errors based on information in packets

received and the timing of the information. In short, the host sends data, the LPD modules receives it,

checks it and adjusts its state. If the state is right and the data is intended for the printer, the data is

forwarded. Otherwise the LPD module interprets it, storing information regarding the job in a

temporary buffer and later discarding it.

Windows clients are easily able to configure an LPR port and print direct to HP printers. Mac OS X

provides the same capability. In addition to these clients, there is also IBM Mainframe, Unix, and

Linux print services to be aware of. The Common Unix Printing System (CUPS) uses LPD, unless

directed to use IPP or JetDirect sockets (Port 9100). LPD print jobs, unless sent over a secure

connection, travel in clear text format that anyone using a sniffer or other packet-analysis software can

read. Using buffer overflow exploitation to execute arbitrary code or creating a denial-of service

(DoS) condition are the most common (generally speaking) vulnerabilities associated with LPD. Since

Port 515 printing is widely used, the general disabling of LPD will likely affect print production in most

large print environments. Disable LPD if not used in the customer’s environment or only enable LPD on

the devices where required. Access Control Lists can also provide LPD related security by only

accepting print jobs from hosts designated in the list.

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HP JetAdvantage Security Manager 10 Device E-LTU Manual de usuario Pagina 76