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. Applica
tions 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 applica
tion. 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 imon(7M) pseudo device driver. 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 inetd(1M). 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_timeout. fam exits
idle_timeout seconds after its
last client disconnects. A
value of 0 causes fam to wait
indefinitely for new connec
tions. The default is five sec
onds.
-f Remain in the foreground instead
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 dis
ables authentication and reduces
access security as described
under SECURITY below. This
overrides the insecure_compati
bility 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 unauthenticated clients.
this user, fam will not tell
unauthenticated clients about
the file's existence. If an
untrusted user is not given in
the configuration 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. Setting
this option to true is the same
as using the -L command-line
option. This option is ignored
if fam is started by inetd.
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 service
remote requests without attempt
ing 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
insecure_compatibility configuration option can be used to
disable authentication. Configuring fam this way opens a
publically known security weakness whereby a "rogue
client" can obtain the names of all the files and directo
ries on the system.
Note that fam never opens the files it's 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
inetd(1M), portmap(1M), fam(3X), imon(7M), stat(1M).
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