Bad user/group via NFSv4 mount: nobody user?

Question

We have 3 servers:

• An NFS server: 1.2.3.4 (rhel 6.8)
• A good NFS client: SERVER5G (rhel6.8)
• A bad NFS client: SERVER6B (rhel6.3)

Problem with the SERVER6B (bad nfs client) is that it shows the user/group for the same NFS mount as "nobody".

NFSv4, RHEL 6 machines.

[root@SERVER5G ~]# ls -la /var/FOODump/
total 55205372
drwxrwxr-x  18 foouser     root            4096 Jul 11 17:40 .
drwxr-xr-x. 31 root     root            4096 Mar 18 12:51 ..
-rw-------   1 foouser     foouser         1117958 Mar 23 10:41 bar.7z
[root@SERVER5G ~]# 
[root@SERVER5G ~]# stat /var/FOODump/bar.7z
  File: `/var/FOODump/bar.7z'
  Size: 1117958     Blocks: 2192       IO Block: 1048576 regular file
Device: 16h/22d Inode: 16          Links: 1
Access: (0600/-rw-------)  Uid: ( 2826/    foouser)   Gid: ( 2826/    foouser)
Access: 2016-03-23 10:41:48.000000000 +0000
Modify: 2016-03-23 10:41:31.000000000 +0000
Change: 2016-03-23 10:41:31.000000000 +0000
[root@SERVER5G ~]# 
[root@SERVER5G ~]# id nobody
uid=99(nobody) gid=99(nobody) groups=99(nobody)
[root@SERVER5G ~]# 
[root@SERVER5G ~]# id foouser
uid=2826(foouser) gid=2826(foouser) groups=2826(foouser)
[root@SERVER5G ~]# 
[root@SERVER5G ~]# df -mP /var/FOODump/
Filesystem                 1048576-blocks   Used Available Capacity Mounted on
1.2.3.4:/var/FOODump         193524 129698     53996      71% /var/FOODump
[root@SERVER5G ~]# 
[root@SERVER5G ~]# mount | grep FOODump
1.2.3.4:/var/FOODump on /var/FOODump type nfs (rw,vers=4,addr=1.2.3.4,clientaddr=1.2.3.5)
[root@SERVER5G ~]# 

and the bad client:

[root@SERVER6B ~]# ls -la /var/FOODump/
total 55205372
drwxrwxr-x  18 nobody nobody        4096 Jul 11 17:40 .
drwxr-xr-x. 31 root   root          4096 Jul  6 06:40 ..
-rw-------   1 nobody nobody     1117958 Mar 23 10:41 bar.7z
[root@SERVER6B ~]# 
[root@SERVER6B ~]# stat /var/FOODump/bar.7z
  File: `/var/FOODump/bar.7z'
  Size: 1117958     Blocks: 2192       IO Block: 1048576 regular file
Device: 18h/24d Inode: 16          Links: 1
Access: (0600/-rw-------)  Uid: (   99/  nobody)   Gid: (   99/  nobody)
Access: 2016-03-23 10:41:48.000000000 +0000
Modify: 2016-03-23 10:41:31.000000000 +0000
Change: 2016-03-23 10:41:31.000000000 +0000
[root@SERVER6B ~]# 
[root@SERVER6B ~]# id nobody
uid=99(nobody) gid=99(nobody) groups=99(nobody)
[root@SERVER6B ~]# 
[root@SERVER6B ~]# id foouser
uid=2826(foouser) gid=2826(foouser) groups=2826(foouser)
[root@SERVER6B ~]# 
[root@SERVER6B ~]# df -mP /var/FOODump/
Filesystem                 1048576-blocks   Used Available Capacity Mounted on
1.2.3.4:/var/FOODump         193524 129698     53996      71% /var/FOODump
[root@SERVER6B ~]# 
[root@SERVER6B ~]# mount | grep FOODump
1.2.3.4:/var/FOODump on /var/FOODump type nfs (rw,vers=4,addr=1.2.3.4,clientaddr=1.2.3.6)
[root@SERVER6B ~]# 

We already tried to umount, rmmod all the NFS kernel modules, mount the /var/FOODump on SERVER6B, but didn't helped.

If we "su - foouser" on SERVER6B, we can "touch testfile":

• on SERVER6B its shown as nobody.
• on SERVER5G its shown as foouser

Question: Why is SERVER6B showing "nobody" user via the NFS?

Answer 1

[root@SERVER6B ~]# umount /var/FOODump
[root@SERVER6B ~]# nfsidmap -c
[root@SERVER6B ~]# mount /var/FOODump

solved the issue..