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I am growing weary of some error messages in my syslog - its showing:

Jul 3 15:16:38 web rpc.idmapd[14535]: nss_getpwnam: name 'nobody' does not map into domain ''

I have check, my hostname is correct as and I even added a valid entry in /etc/hostname . I have edited my /etc/idmapd.conf to reflect this domain name, this error message log every 10minutes and its becoming frustrating, I do not know why or whats causing it, the nfs server is working ok, with correct entries and now message in the log.

I am using centos6

-- Ofcoure, i have substituted with my real domain

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I had the same issue on 2 NFSv4 clients and it was related to some files and directories having unknown uid and gid. Those files had been copied from an old server with a completely different list of users. On the nfs server they will show up with a numeric uid/gid. But on the clients, idmapd maps those to the user nobody and group nogroup but issue the warning you mention in the log files.

I think you should check your nfs exported directories if they contain such files. The easiest way I've found was to do it with find:

find /path/to/your_nfs_dir/ -user nobody -or -group nogroup -ls

and you can even change them right away if you want to make those files to belong to some existing user/group:

find /path/to/your_nfs_dir/ -user nobody -exec chown myuser {} \;
find /path/to/your_nfs_dir/ -group nogroup -exec chgrp mygroup {} \;

You need to do this on one of the client, as on the nfs server the files will not be identified as belonging to nobody/nogroup.

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I am also having this problem, I was able to determine that the idmapd map problem is partly a kernel problem on the client machine.

First, on the nfs server, logs show that idmapd is being fed numerical ids for some users instead of names, by the nfs client. This behavior is related to the kernel on the client, with the kernel,

It fails, but with, uid mapping works, however gid mapping still fails.

The only way I've been able to get both uid and gid mapping to work is to revert to NFSv3.

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