"Network Error 53", "The data area passed to a system call is too small" or "Unknown Error"
Client for NFS included with Windows Server 2003 R2 returns different errors when trying to access NFS shares on UNIX-based NFS servers. The exact error message may depend on your environment - you might get one or more from the ones mentioned above. And, at the same time, SFU 3.5 Client for NFS may work just fine.
Analyzing the network traffic may show MOUNT or NFS calls being "rejected for security reasons (5)".
The R2 Client for NFS uses high ports (>1024) to connect to NFS servers and that's known to cause the above errors. There are two ways to fix this -
Should you worry about security when you change your NFS server to allow connection from high ports? The answer is NO. An excerpt from RFC2623 says so -
Many NFS servers will require that the client send its NFS requestsfrom UDP or TCP source ports with values < 1024. The theory is thatbinding to ports < 1024 is a privileged operation on the client, andso the client is enforcing file access permissions on its end. Thetheory breaks down because: * On many operating systems, there are no constraints on what port what user can bind to.* Just because the client host enforces the privilege on binding to ports < 1024 does not necessarily mean that a non-privileged user cannot gain access to the port binding privilege. For example with a single-user desk-top host running a UNIX operating system, the user may have knowledge of the root user password. And even if he does not have that knowledge, with physical access to the desk-top machine, root privileges are trivially acquired.
Many NFS servers will require that the client send its NFS requestsfrom UDP or TCP source ports with values < 1024. The theory is thatbinding to ports < 1024 is a privileged operation on the client, andso the client is enforcing file access permissions on its end. Thetheory breaks down because:
* On many operating systems, there are no constraints on what port what user can bind to.* Just because the client host enforces the privilege on binding to ports < 1024 does not necessarily mean that a non-privileged user cannot gain access to the port binding privilege. For example with a single-user desk-top host running a UNIX operating system, the user may have knowledge of the root user password. And even if he does not have that knowledge, with physical access to the desk-top machine, root privileges are trivially acquired.
On the other hand, turning off low ports check on the NFS servers ensures compatibility with NFS clients irrespective of clients using high or low ports to access the NFS servers.
Note that above mentioned errors can be caused by number of other factors as well so if the solutions mentioned above don't work for you - focus your troubleshooting on other aspects.