I have the following problem:
a win32 client application needs file-level access to a UNC share (e.g. '\\server\fileshare') located in a network segment only accessible via a NAT firewall (that is, all connections to this UNC share go over the NAT).
Having configured the firewall to allow NetBios traffic (TCP port 139), I have managed to get the application to run satisfactorily.
However, as soon as two clients are up and performing any sort of File I/O on this share (not on the same file or even in the same directory necessarily), one of the clients chokes up.
I have tested this on OS-level by simply mounting the share as a network drive and interacting with it and even here I have difficulties as soon as I try doing concurrent accesses from multiple systems behind the NAT.
I have configured numerous protocols (MS-SQL, mysql, http, etc.) to pass through the NAT without difficulty. What is the difference with NetBIOS/SMB?
Is there any way to get concurrency over the NAT and if so, how?
BTW, The situation is reproducible with a number of different NAT firewalls, specifically the ISA Server from Microsoft and some ipchains variant running on linux/bsd (it is off-site and I don't have the exact details) seem to have this trouble.
Any information regarding this situation would definitely make my day.
Many thanks and best regards,