We have an NFS share on a Debian Linux host which is mounted on a Win XP host using SFU. We can create folders on a share or delete files from it but it's not possible to perform file write or read operations on it (say, copy file.ext n:\ blocks for a long time and finally terminates with The remote system refused the network connection error). We tried both TCP and UDP on a client side when mounting. All ports are open on firewall between these two machines. There is nothing relevant in Win XP Event Log and in syslog on a server side. And this is not a permission problem obviously because we can create folders. What can we do to find a root cause of this?
Update: I captured an NFS session using Wireshark and found that the root cause was a locking problem, the NFS server keeped answering NFS_DENIED_GRACE_PERIOD status to client calls. And the question now is how to fix this locking issue?
99.9999% of the time when something says connection refused it has something to do with either the software or the hardware firewall. I suggest you telnet first to the ports in question from source to destination and check.