nsupdate + SSH tunnel

[Jari]

> nsupdate can use TCP connections and be told to send updates to a
> specific address and port number. So in theory you could make SSH do
> port forwarding for whatever port/address you tell nsupdate to
> use. But this seems excessively painful. What's wrong with
> ssh trusted-host nsupdate < my-dns-update-file
>

I'm calling nsupdate from java application and I want to catch return value
and output/error messages.

I have configured the following test system:

dns server (ip x.x.x.x):
- named in port 153
- sshd

client server (ip i.i.i.i):
- ssh tunnel to dns server (ssh -L 533:x.x.x.x:153 x.x.x.x sleep 99999)

When I try something like this:
# nsupdate -v
> server x.x.x.x 153
> local i.i.i.i 533
> update add...

Update succeeds but nsupdate does not use configured SSH tunnel.
Can nsupdate+tunnel be used like this?