NFS server refusing hostname that is allowed

I would think hard about using sync. I'm reminded about the Dirty Harry 'Do you feel lucky' speech.

NFS v2 and v3 is designed such that when the write is acked from the server to the client the data is on disk. This allows NFS to be stateless, and, therefore, the server COULD reboot between each request. One hopes not, but it could happen.

This means that if the client sees the ACK on the write then it doesn't have to care anymore about the data being on disk.

If you use async then this is not true anymore. It will be way faster though. Basically though if you use async, and, the server crashes, you probably should reboot the clients unless you know exactly what they do since if they are expecting to keep multiple files in sync the client may believe they are in sync, when, in fact, they are not.

This is a good example of the difference between authentication and authorization. In this scenario the authentication succeeded, but the authorization on the host's directory is likely to be the problem. To test, you can try setting the host's directory permissions recursively to 777 (don't forget to change this again later).

Things to check:

• Are the username and uuid of the user on the client and the host the same?
• Are permissions correctly set on the host?
• Does NFS on the host server have correct permissions to access the files it is supposed to share? ie. Is NFS running as root, and if not, do the files it is trying to access have correct permissions set to allow them to be accessed by the NFS daemon itself?