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pcnfsd(8c)

25 April 1991
Aliases: rpc.pcnfsd(8c)

linux_pcnfsd2

RPC Server That Supports ONC Clients

NAME

pcnfsd - (PC)NFS authentication and print request server

SYNOPSIS

/usr/etc/rpc.pcnfsd

AVAILABILITY

This program is freely redistributable.

DESCRIPTION

pcnfsd is an RPC server that supports ONC clients on PC (DOS, OS/2, Macintosh, and other) systems. This page describes version two of the pcnfsd server.
rpc.pcnfsd may be started from /etc/rc.local or by the inetd(8) superdaemon. It reads the configuration file /etc/pcnfsd.conf if present, and then services RPC requests directed to program number 150001. This release of the pcnfsd daemon supports both version 1 and version 2 of the pcnfsd protocol. Consult the rpcgen source file pcnfsd.x for details of the protocols.
The requests serviced by pcnfsd fall into three categories: authentication, printing, and other. Only the authentication and printing services have administrative significance.

AUTHENTICATION

When pcnfsd receives a PCNFSD_AUTH or PCNFSD2_AUTH request, it will "log in" the user by validating the username and password and returning the corresponding uid, gids, home directory, and umask. If pcnfsd was built with the WTMP compile-time option, it will also append a record to the wtmp(5) data base. If you do not wish to record PC "logins" in this way, you should add a line of the form
wtmp off
to the /etc/pcnfsd.conf file.
By default, pcnfsd will only allow authentication or print requests for users with uids in the range 101 to 60002. (This corresponds in SVR4 to the range for non-system accounts.) To override this, you may add a line of the form
uidrange range[,range]...
to the /etc/pcnfsd.conf file. Here, each range is of the form
uid
or
uid-uid
indicating an inclusive range.

PRINTING

pcnfsd supports a printing model based on the use of NFS to transfer the actual print data from the client to the server. The client system issues a PCNFSD_PR_INIT or PCNFSD2_PR_INIT request, and the server returns the path to a spool directory which the client may use and which is exported by NFS. pcnfsd creates a subdirectory for each of its clients: the parent directory is normally /usr/spool/pcnfs and the subdirectory is the hostname of the client system. If you wish to use a different parent directory, you should add a line of the form
spooldir path
to the /etc/pcnfsd.conf file.
Once a client has mounted the spool directory using NFS and has transferred print data to a file in this directory, it will issue a PCNFSD_PR_START or PCNFSD2_PR_START request. pcnfsd handles this, and most other print-related requests, by constructing a command based on the printing services of the server operating system and executing the command using the identity of the PC user. Since this involves set-user-id privileges, pcnfsd must be run as root.
Every print request from the client includes the name of the printer which is to be used. In SunOS, this name corresponds to a printer definition in the /etc/printcap(5) database. If you wish to define a non-standard way of processing print data, you should define a new printer and arrange for the client to print to this printer. There are two ways of setting up a new printer. The first involves the addition of an entry to /etc/printcap(5) and the creation of filters to perform the required processing. This is outside the scope of this discussion. In addition, pcnfsd includes a mechanism by which you can define virtual printers known only to pcnfsd clients. Each printer is defined by a line in the /etc/pcnfsd.conf file of the following form
printer name alias-for command
name is the name of the printer you want to define. alias-for is the name of a "real" printer which corresponds to this printer. For example, a request to display the queue for name will be translated into the corresponding request for the printer alias-for. If you have defined a printer in such a way that there is no "real" printer to which it corresponds, use a single "-" for this field. (See the definition of the printer test below for an example.) command is a command which will be executed whenever a file is printed on name. This command is executed by the Bourne shell, /bin/sh using the -c option. For complex operations you should construct an executable shell program and invoke that in command. Within command the following tokens will be replaced:
Token Substitution
$FILE Replaced by the full path name of the print data file. When the command has been executed, the file will be unlinked.
$USER Replaced by the username of the user logged in to the client system.
$HOST Replaced by the host name of the client system.
Consider the following example /etc/pcnfsd.conf file:
printer rotated lw /usr/local/bin/enscript -2r $FILE
printer test - /usr/bin/cp $FILE /usr/tmp/$HOST-$USER
If a client system prints a job on the printer rotated the utility enscript will be invoked to pre-process the file $FILE. In this case, the -2r option causes the file to be printed in two-column rotated format on the default PostScript® printer. If the client requests a list of the print queue for the printer rotated the pcnfsd daemon will translate this into a request for a listing for the printer lw.
The printer test is used only for testing. Any file sent to this printer will be copied into /usr/tmp. Any request to list the queue, check the status, etc. of printer test will be rejected because the alias-for has been specified as "-".

RECONFIGURATION

pcnfsd will detect when printers are added or deleted and will rebuild its list of valid printers. To do this, it checks the modification time of /etc/printcap for BSD-style systems or /etc/lp/printers for SVR4-based systems. However, it does not monitor the file /etc/pcnfsd.conf for updates; if you change this file, it is still necessary to kill and restart pcnfsd in order that the changes can take effect.

FILES

/etc/pcnfsd.conf
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