[SOLVED] NFSv4 & NAT traversal

ggeeoo · 09-01-2009, 04:31 PM

I have to use NFS behind a NAT so I decided to try NFSv4 since traversing NAT with NFSv3 is not possible. On the server I have the following configuration in /etc/exports:

Code:

/export       *(rw,fsid=root,insecure,no_subtree_check,async,all_squash)
/export/test  *(rw,nohide,insecure,async,no_subtree_check)

On the client I give

Code:

mount -t nfs4 -o tcp nfs4_server:/test /mnt/test

The problem is that the above command works just fine when the client is directly connected in the same network as the server, but it doesn't work when the client is connected via NAT (the configuration of client is otherwise the same). It fails with the following error:

Code:

mount.nfs4: Operation not permitted

So the problem seems to be caused by NAT.

This seems strange to me: in NFSv4, the client establishes a single outbound tcp connection to the server (on the remote port 2049). Why is NAT causing a problem to that? After all, I can successfully establish this tcp connection using netcat.

ggeeoo · 09-01-2009, 10:13 PM

Ok, I don't know why, but the following worked:

I changed the following line in /etc/exports, from

Code:

/export/test  *(rw,nohide,insecure,async,no_subtree_check)

to

Code:

/export/test  *(rw,fsid=1,nohide,insecure,async,no_subtree_check)

Apparently, nfs couldn't assign an fsid to /export/test automatically for some reason (maybe because /export/test is actually a bind mount) so I had to do it manually. I don't see how this relates to the NAT issue though.