idmapd(8) — Linux manual page


RPC.IDMAPD(8)          BSD System Manager's Manual         RPC.IDMAPD(8)

NAME         top

     rpc.idmapd — NFSv4 ID <-> Name Mapper

SYNOPSIS         top

     rpc.idmapd [-h] [-f] [-v] [-C] [-S] [-p path] [-c path]

DESCRIPTION         top

     rpc.idmapd is the NFSv4 ID <-> name mapping daemon.  It provides
     functionality to the NFSv4 kernel client and server, to which it
     communicates via upcalls, by translating user and group IDs to
     names, and vice versa.

     The system derives the user part of the string by performing a
     password or group lookup.  The lookup mechanism is configured in

     By default, the domain part of the string is the system's DNS
     domain name.  It can also be specified in /etc/idmapd.conf if the
     system is multi-homed, or if the system's DNS domain name does not
     match the name of the system's Kerberos realm.

     When the domain is not specified in /etc/idmapd.conf the local DNS
     server will be queried for the _nfsv4idmapdomain text record. If
     the record exists that will be used as the domain. When the record
     does not exist, the domain part of the DNS domain will used.

     Note that on more recent kernels only the NFSv4 server uses
     rpc.idmapd.  The NFSv4 client instead uses nfsidmap(8), and only
     falls back to rpc.idmapd if there was a problem running the
     nfsidmap(8) program.

     The options are as follows:

     -h           Display usage message.

     -v           Increases the verbosity level (can be specified
                  multiple times).

     -f           Runs rpc.idmapd in the foreground and prints all
                  output to the terminal.

     -p path      Specifies the location of the RPC pipefs to be path.
                  The default value is "/var/lib/nfs/rpc_pipefs".

     -c path      Use configuration file path.  This option is

     -C           Client-only: perform no idmapping for any NFS server,
                  even if one is detected.

     -S           Server-only: perform no idmapping for any NFS client,
                  even if one is detected.


     rpc.idmapd recognizes the following value from the [general]
     section of the /etc/nfs.conf configuration file:

                  Equivalent to -p.

     All other settings related to id mapping are found in the
     /etc/idmapd.conf configuration file.

EXAMPLES         top

     rpc.idmapd -f -vvv

     Runs rpc.idmapd printing all messages to console, and with a
     verbosity level of 3.

FILES         top

     /etc/idmapd.conf, /etc/nfs.conf

SEE ALSO         top

     idmapd.conf(5), nfs.conf(5), nfsidmap(8)

AUTHORS         top

     The rpc.idmapd software has been developed by Marius Aamodt Eriksen

COLOPHON         top

     This page is part of the nfs-utils (NFS utilities) project.
     Information about the project can be found at  If you have a bug
     report for this manual page, see
     ⟨⟩.  This page was
     obtained from the project's upstream Git repository
     ⟨git://⟩ on
     2023-06-23.  (At that time, the date of the most recent commit that
     was found in the repository was 2023-06-12.)  If you discover any
     rendering problems in this HTML version of the page, or you believe
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     COLOPHON (which is not part of the original manual page), send a
     mail to

BSD                         February 3, 2003                         BSD

Pages that refer to this page: nfs(5)nfs.conf(5)nfsconf(8)nfsdclnts(8)