fam



fam(1M)                                                                fam(1M)




NAME

       fam - file alteration monitor


SYNOPSIS

       /usr/etc/fam [ -f | -v | -d ] [ -l | -t NFS_polling_interval ]
            [ -T idle_timeout ] [ -p program.version ] [ -L ] [ -C ]
            [ -c config_file ]


DESCRIPTION

       fam  is a server that tracks changes to the filesystem and relays these
       changes to interested applications.  Applications such  as  fm(1G)  and
       mailbox(1)  present  an  up-to-date  view  of  the  filesystem.  In the
       absence of fam, these applications and others like them are  forced  to
       poll the filesystem to detect changes.  fam is more efficient.

       Applications can request fam to monitor any files or directories in any
       filesystem.  When fam detects changes to monitored files,  it  notifies
       the  appropriate  application.   The  FAM  API  provides a programmatic
       interface to fam; see fam(3X).

       fam is informed of filesystem changes as  they  happen  by  the  kernel
       through the dnotify fcntl.  If asked to monitor files on an NFS mounted
       filesystem, fam tries to use fam on the NFS server  to  monitor  files.
       If  fam  cannot  contact a remote fam, it polls the files instead.  fam
       also polls special files.

       Normally,  fam  is  started  by  xinetd(8).   It  is  registered   with
       portmap(1M) as performing the sgi_fam service.


OPTIONS

       -l                        Disable  polling  of  NFS files.  It does not
                                 disable use of remote fam on NFS servers, nor
                                 does it disable polling of local files.

       -t NFS_polling_interval   Set   the   interval  for  polling  files  to
                                 NFS_polling_interval seconds.  The default is
                                 six seconds.

       -T idle_timeout           Set  the  idle timeout interval to idle_time-
                                 out.  fam exits  idle_timeout  seconds  after
                                 its  last  client  disconnects.  A value of 0
                                 causes fam to wait indefinitely for new  con-
                                 nections.  The default is five seconds.

       -f                        Remain  in the foreground instead of spawning
                                 a child and exiting.  This option is  ignored
                                 if fam is started by inetd.

       -v                        Turn on verbose messages.

       -d                        Enable verbose messages and debug messages.

       -p program.version        Use  the  specified  RPC  program and version
                                 numbers.

       -L                        Local-only  mode.   fam  will   only   accept
                                 requests  from  clients  running on the local
                                 machine.  This overrides the local_only  flag
                                 in  the  configuration  file.  This option is
                                 ignored if fam is started by inetd.

       -C                        Compatibility mode.  This disables  authenti-
                                 cation   and   reduces   access  security  as
                                 described under SECURITY below.   This  over-
                                 rides  the insecure_compatibility flag in the
                                 configuration file.

       -c config_file            Read configuration information from the given
                                 file   rather  than  the  default,  which  is
                                 /etc/fam.conf.


CONFIGURATION FILE

       In addition to its command-line options, fam’s  behavior  can  also  be
       controlled  through  its  configuration  file.   By  default,  this  is
       /etc/fam.conf; the -c command-line option can be  used  to  specify  an
       alternate  file.   Configuration  lines are in the format option=value.
       Lines beginning with # or ! are ignored.  fam recognizes the  following
       options:

       insecure_compatibility    If  set to true, this disables authentication
                                 and  reduces  access  security  as  described
                                 under  SECURITY  below.   This  is  false  by
                                 default.  Setting this option to true is  the
                                 same as using the -C command-line option.

       untrusted_user            This  is  the  user  name  or UID of the user
                                 account which fam will  use  for  unauthenti-
                                 cated clients.  If a file can’t be stat’ed by
                                 this user, fam will not tell  unauthenticated
                                 clients  about  the  file’s existence.  If an
                                 untrusted user is not given in the configura-
                                 tion file, fam will write an error message to
                                 the system log and terminate.

       local_only                If set to true, fam will ignore requests from
                                 remote fams.  This is false by default.  Set-
                                 ting this option to true is the same as using
                                 the  -L  command-line option.  This option is
                                 ignored if fam is started by inetd.

       idle_timeout              This is the time in  seconds  that  fam  will
                                 wait  before  exiting  after  its last client
                                 disconnects.  The default  is  five  seconds.
                                 This  option is overridden by the -T command-
                                 line option.

       nfs_polling_interval      This  is  the  interval  in  seconds  between
                                 polling  files  over  an NFS filesystem.  The
                                 default is six seconds.  This option is over-
                                 ridden by the -t command-line option.

       xtab_verification         If  set  to  true, fam will check the list of
                                 exported filesystems when remote requests are
                                 received  to verify that the requests fall on
                                 filesystems  which  are   exported   to   the
                                 requesting  hosts.   This is true by default.
                                 If this option is set to false, fam will ser-
                                 vice  remote  requests  without attempting to
                                 perform the verification.  If the  local_only
                                 configuration   option   or  -L  command-line
                                 option  is  used,  xtab_verification  has  no
                                 effect.


SECURITY

       For  backward  compatibility,  the  -C  command-line  option  and inse-
       cure_compatibility configuration option can be used to disable  authen-
       tication.   Configuring  fam this way opens a publically known security
       weakness whereby a "rogue client" can obtain the names of all the files
       and directories on the system.

       Note that fam never opens the files its monitoring, and cannot be used
       by a rogue client to read the contents of any file on the system.   fam
       only  gives  out  the names of monitored files, and only monitors files
       which the client can stat(1M).  Users can stat a  file  without  having
       read  permission  on  it  as long as they have search permission on the
       directory containing it.


FILES

       /etc/fam.conf


SEE ALSO

       xinetd(8), portmap(1M), fam(3X), stat(1M).



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