Provided by: lprng_3.8.B-6_amd64 bug


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


       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
              # Only accept spooling (LPR) from
              # Engineering Lab or the Dean's office
              # Do not accept forwarded jobs for printing
              # Allow only the administrators control access
              ACCEPT SERVICE=C,M 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
              # 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
              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

       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 X 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 capabilities.  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 originated 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
       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

          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 (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 = IP address[/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

       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
               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= matches all address 130.191.X.X
           IP= 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:
       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.


       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:


       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.


       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/lprng/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


       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).


       Patrick Powell <>.


       LPRng  is a enhanced printer spooler system with functionality similar to the Berkeley LPR
       software.   The  LPRng  developer  mailing  list   is;
       subscribe  by visiting or sending
       mail to with the word subscribe in the body.
       The software is available via