LPD.PERMS(5)                                                      LPD.PERMS(5)



NAME
       lpd.perms - permissions control file for the LPRng line printer spooler system

DESCRIPTION
       The file lpd.perms is used to provide permission information for the
       LPRng Printer spooler system.  Blank lines and all characters after a
       hash sign (``#'') to the end of line are ignored.  If a hash sign is
       desired in the permission information, it should be escaped with a
       backslash (``\'').  All other lines specify permissions entry and
       should be of the following form:
              ACCEPT [[not] key = value[,value]* ]*
              REJECT [[not] key = value[,value]* ]*
              DEFAULT ACCEPT
              DEFAULT REJECT

       Each LPD service request is checked against the entries in the
       permissions database or file.  The following is a typical permissions
       file:
              # Set default permissions
              DEFAULT ACCEPT
              # Reject any connections from outside our subnet
              REJECT SERVICE=X NOT REMOTEIP=130.191.0.0/255.255.0.0
              # Only accept spooling (LPR) from
              # Engineering Lab or the Dean's office
              REJECT SERVICE=R NOT REMOTEHOST=*.eng.sdsu.edu,dean.sdsu.edu
              # Do not accept forwarded jobs for printing
              REJECT SERVICE=R FORWARD
              # Allow only the administrators control access
              ACCEPT SERVICE=C,M REMOTEHOST=spooler.eng.sdsu.edu REMOTEUSER=root,papowell
              ACCEPT SERVICE=C,M SERVER REMOTEUSER=root,papowell
              # Allow only the user on the same host who spooled job to remove it
              ACCEPT SERVICE=M SAMEUSER SAMEHOST
              # Allow users to check status
              ACCEPT SERVICE=C LPC=status
              # Require connection for other operations over UNIX socket
              # not TCP/IP port.  Effectively requiring them to be made from the
              # localhost
              ACCEPT SERVICE=C UNIXSOCKET
              REJECT SERVICE=C

              # Variation - accept all spooled jobs,  but then apply
              #  permissions checking when job is printed.  Allows
              #  prevents remote spoolers from locking up trying resend
              #  same request
              ACCEPT SERVICE=R
              REJECT SERVICE=P NOT REMOTEHOST=*.eng.sdsu.edu,dean.sdsu.edu


       Permission checking is done by using a set of keys (or fields) with
       associated values to check for permission.  The SERVICE key has value P
       for printing (i.e.- unspooling), R for spooling (i.e.- LPR request), P
       for printing (i.e., after job has been spooled), C printer control
       (i.e. - LPC), M for removal (i.e.- LPRM request), and Q for queue
       information (i.e.- LPQ request).  The key is used when checking for
       connection information.

       Initially, all of the keys have undefined or NULL values, and are
       assigned values during the permissions checking process.  When a
       connection is made to the server, it assigns The REMOTEHOST (alias
       REMOTEIP) key the list of IP addresses and hostnames determined by
       doing a reverse Domain Name Service (DNS) lookup on the remote host's
       IP address.  If the reverse DNS fails, then only the IP address will be
       used.  The REMOTEPORT (PORT is an alias for REMOTEPORT) is assigned the
       port number of the connection origination.  The UNIXSOCKET key will
       match (be true) if the connection is over a UNIX socket.  By
       convention, this is from the localhost.  Finally, the SERVICE value is
       assigned X, and the lpd server will check the database to see if the
       connection is accepted or rejected.

       The server will then read the request information from the connection.
       If the request is for an authenticated data transfer, the server will
       invoke the appropriate authentication mechanism which will assign AUTH
       a true (or matching) value, AUTHTYPE the type of authentication,
       AUTHUSER the authenticated user id value, which may differ from the
       actual user name, and AUTHFROM the authenticated identification of the
       originator of the request, which may be a server if the request is
       forwarded.

       Next, the SERVICE value is set to R, C, M, or Q depending on whether it
       is an LPR, LPC, LPRM, or LPQ request, and the LPC value set to the
       requested LPC command if it was an LPC request.  If the request
       contained a user name, then REMOTEUSER is set to this name.  If the
       request contained a printer name, then PRINTER is set to the printer
       name.  If the request is a print request, then the HOST value is set to
       the list of host names and IP addresses given by a DNS lookup of the
       value in the H field of the job.  The database is scanned again to
       determine if the operation can be performed on the requested queue.  To
       simplify the rule writing, if the operation requires modification or
       checking of individual jobs, such as the LPC, LPQ, or LPRM commands,
       then the various checks that depend on jobs will succeed in this step.

       Finally, if the operation requires modification or checking of
       individual jobs, such as the LPC, LPQ, or LPRM commands, then the
       specified print queue is scanned, and for each job in the print queue,
       the HOST and USER values are set to the host and user values in the
       control file for the job.

       The database is checked as follows.  Each line of the permissions file
       is scanned for key names and values, and these are matched against the
       request keys information.  When all matches on a line are made, then
       search terminates with the specified action (ACCEPT/REJECT).  If no
       match is found the default permission value is used.  The DEFAULT key
       is used to specify the current default permission to be used for
       successful matches or if there is no match after scanning the entire
       permissions database.

       The following keys provide some additional checking capabilties.  The
       REMOTEGROUP entry checks that the REMOTEUSER value appears in a group
       or netgroup entry in the system database, and the GROUP entry for the
       USER value.  For example, GROUP=student*,staff* would check to see if
       any of the group names matching student* or staff* have the specified
       user name in them.  If a system has the netgroups capability, a
       printer, group, or remotegroup name starting with a @ will be treated
       as a netgroup name, and specified user name or printer will be checked
       to see if it is in the group.

       The SERVER entry will be true (match) if the request originated from
       the print server.  The SAMEHOST is true (matches) if the REMOTEHOST and
       HOST values have a common entry, i.e. - are the same host.  The
       SAMEUSER is true (matches) if the REMOTEUSER and USER values are
       identical.  The AUTHSAMEUSER is true (matches) if the AUTHUSER value
       that orginated the request and the AUTHUSER which was used to transfer
       a job are identical.  AUTHJOB is true (matches) if the job was
       transferred using authentication.  The FORWARD value is an alias for
       NOT SAMEHOST.

       The CONTROLLINE value can be used to determine if there is a matching
       line in the control file.  This facility has been used to ensure that
       jobs contain various information fields in order to be printed.

       Key          Match Connect Job   Job    LPQ  LPRM  LPC
                                  Spool Print
       SERVICE      S     'X'     'R'   'P'    'Q'  'M'   'C,S'
       USER         S     -       JUSR  JUSR   JUSR JUSR  JUSR
       HOST         S     RH      JH    JH     JH   JH    JH
       GROUP        S     -       JUSR  JUSR   JUSR JUSR  JUSR
       REMOTEPORT   N     PORT    PORT  -      PORT PORT  PORT
       REMOTEUSER   S     -       JUSR  JUSR   JUSR CUSR  CUSR
       REMOTEHOST   S     RH      RH    JH     RH   RH    RH
       UNIXSOCKET   V     SK      SK    SK     SK   SK    SK
       REMOTEGROUP  S     -       JUSR  JUSR   JUSR CUSR  CUSR
       CONTROLLINE  S     -       CL    CL     CL   CL    CL
       PRINTER      S     -       PR    PR     PR   PR    PR
       FORWARD      V     -       SA    -      -    SA    SA
       SAMEHOST     V     -       SA    -      SA   SA    SA
       SAMEUSER     V     -       -     -      SU   SU    SU
       SERVER       V     -       SV    -      SV   SV    SV
       AUTH         V     -       AU    -      AU   AU    AU
       AUTHTYPE     S     -       AU    -      AU   AU    AU
       AUTHUSER     S     -       AU    -      AU   AU    AU
       AUTHSAMEUSER S     -       AU    -      AU   AU    AU
       AUTHFROM     S     -       AU    -      AU   AU    AU
       AUTHJOB      V     -       AU    -      AU   AU    AU
         PORT is alias for REMOTEPORT
         REMOTEIP is alias for REMOTEHOST
         IP is alias for HOST

       KEY:
          JH = HOST          host in control file
          RH = REMOTEHOST    connecting host name/IP
          JUSR = USER        user in control file
          CUSR = REMOTEUSER  user from control request
          JIP= IP            host/IP addr of host in control file
          RIP= REMOTEIP      host/IP addr of requesting host
          PORT=              connecting host origination port
           SK=  match if connection over a UNIX socket
          CONTROLLINE=       pattern match of control line in control file
          FW= IP of source of request == IP of host in control file
          SA= IP of source of request == IP of host in control file
          SU= user from request == user in control file
          SA= IP of source of request == IP of server host
          SV= matches if from same address as server
          AU= value determined by server authentication operation
                             AUTH is true if authenticated transfer,
                             TYPE is set to the type of authentication (pgp, kerberos, etc)
                             AUTHUSER is user authentication id
                             AUTHFROM is sender authentication id (can be remote server)
                             AUTHSAMEUSER matches if remote user authentication id matches original
                             user authentication id
                             AUTHJOB it true if print job has authentication
       Match: S = string with wild card, IP = IPaddress[/netmask],
          N = low[-high] number range, V = exact value match
       SERVICE: 'X' - Connection request; 'R' - lpr request from remote host;
           'P' - print job in queue; 'Q' - lpq request, 'M' - lprm request;
           'C' - lpc spool control request; 'S' - lpc spool status request
          'U' - administratively allowed user operation
       NOTE: when printing (P action), the remote and job check values
          (i.e. - RUSR, JUSR) are identical.


       The special key letter=patterns searches the control file line starting
       with the (upper case) letter, and is usually used with printing and
       spooling checks.  For example, C=A*,B* would check that the class
       information (i.e.- line in the control file starting with C) had a
       value starting with A or B.

       A permission line consists of a list of tests and a result value.  If
       all of the tests succeed, then a match has been found and the
       permission testing completes with the result value.  You use the
       DEFAULT reserved word to set the default ACCEPT/DENY result.  The NOT
       keyword will reverse the sense of a test.

       Each test can have one or more optional values separated by commas. For
       example USER=john,paul,mark has 3 test values.  The Match value
       specifies how the matching is done.

       S = string type match - string match with glob.
           Format:  string with wildcards (*)
               * matches 0 or more chars
           Character comparison is case insensitive.
           For example - USER=th*s matches uTHS, This, This, Theses

       IP = IP address and submask.  IP address must be in dotted form.
           Format: x.x.x.x[/y.y.y.y or /z]
               x.x.x.x is IP address
               y.y.y.y is optional submask, default is 255.255.255.255
               z is a netmask with most significant z bits set.
           Match is done by IP address to a 32 bit value and using:
               success = ((x ^ IP ) & y) == 0   (C language notation)
           i.e.- only bits where mask is non-zero are used in comparison.
           For example - IP=130.191.0.0/255.255.0.0 matches all address 130.191.X.X
           IP=130.191.0.0/16 has the same value.

       N = numerical range  -  low-high integer range.
           Format: low[-high]
           Example: PORT=0-1023 matches a port in range 0 - 1023 (privileged)

       The authentication entries AUTH, AUTHTYPE, AUTHUSER, AUTHSAMEUSER and
       AUTHFROM can be used to check permissions for authenticated operations.
       AUTH is set (true) if authentication was done.  We can use this to
       reject non-authenticated transfers:
       REJECT NOT AUTH
       The AUTHTYPE will match the authentication type being used or requested
       by the remote client or server.  The AUTHUSER matches the original
       client authentication information used by the client to make a request
       to the server, and the AUTHFROM matches the sender authentication
       information.  The AUTHSAMEUSER will match if the remote client or user
       authentication id is the same as that used for the job generation.

LPC=OP
       The LPC=op entry is useful to allow various users to perform
       administration operations.  The following permissions entry would
       allows users to hold or release their own jobs:
       ACCEPT SERVICE=C SAMEUSER SAMEHOST LPC=release

DNS, IPV6, AND MULTIHOMED HOSTS
       There is a subtle problem with names and IP addresses which are
       obtained for 'multi-homed hosts', i.e. - those with multiple ethernet
       interfaces,  and for IPV6 (IP Version 6),  in which a host can have
       multiple addresses,  and for the normal host which can have both a
       short name and a fully qualified domain name.

       When performing an IP address match,  the entire list of IP addresses
       for a system will now be checked.  If one of these matches, then
       success is reported.  Similarly,  the entire list of host names and
       aliases will be checked.  If one of these matches,  then success will
       be reported.

FILES
       The files used by LPRng are set by values in the printer configuration
       file.  The following are a commonly used set of default values.
       /etc/LPRng/lpd.conf                          LPRng configuration file
       ${HOME}/.printcap                            user printer description file
       /etc/printcap                                printer description file
       /etc/LPRng/lpd.perms                         permissions
       /var/run/lpd                                 lock file for queue control
       /var/spool/lpd                               spool directories
       /var/spool/lpd/QUEUE/control                 queue control
       /var/spool/lpd/QUEUE/log                     trace or debug log file
       /var/spool/lpd/QUEUE/acct                    accounting file
       /var/spool/lpd/QUEUE/status                  status file

SEE ALSO
       lpd.conf(5), lpc(8), lpd(8), checkpc(8), lpr(1), lpq(1), lprm(1),
       printcap(5), pr(1), lprng_certs(1), lprng_index_certs(1).

HISTORY
       LPRng is a enhanced printer spooler system with functionality similar
       to the Berkeley LPR software.  The LPRng mailing list is
       lprng@lprng.com; subscribe by sending mail to lprng-request@lprng.com
       with the word subscribe in the body.  The software is available from
       ftp://ftp.lprng.com/pub/LPRng.

AUTHOR
       Patrick Powell <papowell@lprng.com>.



LPRng                             LPRng-3.9.0                     LPD.PERMS(5)
