rpc.idmapd — NFSv4 ID <-> Name Mapper


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


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 part of the string by performing a password or group lookup. The lookup mechanism is configured in /etc/idmapd.conf

By default, the 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:


Display usage message.


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


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 deprecated.


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


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

Configuration Files

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.


rpc.idmapd -f -vvv

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


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

See Also

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


The rpc.idmapd software has been developed by Marius Aamodt Eriksen ⟨marius@citi.umich.edu⟩.

Referenced By

idmapd.conf(5), ipa-client-automount(1), nfs(5), nfs.conf(5), nfsconf(8).

The man page rpc.idmapd(8) is an alias of idmapd(8).

February 3, 2003