Provided by:
nfs-common_1.2.5-3ubuntu3_i386 
NAME
nfsidmap - The NFS idmapper upcall program
DESCRIPTION
The file /usr/sbin/nfsidmap is used by the NFS idmapper to translate
user and group ids into names, and to translate user and group names
into ids. Idmapper uses request-key to perform the upcall and cache the
result. /usr/sbin/nfsidmap should only be called by request-key, and
will perform the translation and initialize a key with the resulting
information.
NFS_USE_NEW_IDMAPPER must be selected when configuring the kernel to
use this feature.
CONFIGURING
The file /etc/request-key.conf will need to be modified so
/sbin/request-key can properly direct the upcall. The following line
should be added before a call to keyctl negate:
create id_resolver * * /usr/sbin/nfsidmap %k %d 600
This will direct all id_resolver requests to the program
/usr/sbin/nfsidmap The last parameter, 600, defines how many seconds
into the future the key will expire. This is an optional parameter for
/usr/sbin/nfsidmap and will default to 600 seconds when not specified.
The idmapper system uses four key descriptions:
uid: Find the UID for the given user
gid: Find the GID for the given group
user: Find the user name for the given UID
group: Find the group name for the given GID
You can choose to handle any of these individually, rather than using
the generic upcall program. If you would like to use your own program
for a uid lookup then you would edit your request-key.conf so it looks
similar to this:
create id_resolver uid:* * /some/other/program %k %d 600
create id_resolver * * /usr/sbin/nfsidmap %k %d 600
Notice that the new line was added above the line for the generic
program. request-key will find the first matching line and run the
corresponding program. In this case, /some/other/program will handle
all uid lookups, and /usr/sbin/nfsidmap will handle gid, user, and
group lookups.
AUTHOR
Bryan Schumaker, <bjschuma@netapp.com>
1 October 2010 nfsidmap(5)