AIX Hidden Files in NFS Can Have Permission Issues

NFS client-server permission mapping:

• NFS relies on UID (user ID) and GID (group ID) matching between client and server.
• If a file is created on the server by userA (UID 1001) and the client has userB (UID 1002), the permissions may appear wrong.

Root squash:

• NFS often maps root on the client to nobody on the server for security (root_squash).
• This prevents root on client from changing server files.
• Hidden files (. prefix) behave like normal files, so permission issues are the same as regular files, but they might not be visible unless ls -a is used.

Check Existing Permissions
# ls -l /mount/dir # Normal files
# ls -la /mount/dir # Hidden files included
Example:
-rw-r--r-- 1 nobody users 50 Sep 26 .hiddenfile
Here:
Owner is nobody → client cannot modify
Group is users → group may not match

Fixing Hidden File Permissions on NFS

A. On the NFS Server
Check UID/GID of the file:
# ls -ln /export/dir
-n shows numeric UID/GID.
Change ownership:
# chown correctuser:correctgroup /export/dir/.hiddenfile
Set proper permissions:
# chmod 600 /export/dir/.hiddenfile # Owner read/write
# chmod 644 /export/dir/.hiddenfile # Owner read/write, others read

B. On the NFS Client
Remount with correct options if UID/GID mismatch:
# mount -o remount,vers=3,rw server:/export/dir /mount/dir
Ensure user on client has same UID/GID as server:
# id username
If mismatch, either create matching UID/GID or adjust server file ownership.

C. Special Case: Root Cannot Modify
If root_squash is active:
You cannot change ownership or permissions as root from the client.
Fix must be done on NFS server by a user with permissions.