Re: ms-nfs41-client mount to FreeBSD 16.0 nfsd fails in VM with NAT

On Tue, Jun 2, 2026 at 9:52 AM Lionel Cons <[email protected]> wrote:
>
> We've hit a problem with ms-nfs41-client release 2026-06-01 with FreeBSD 16.0:
>
> If Windows runs in a VM with NAT an attempt to mount fails with Error
> Code 59 (Unexpected network error), but if the VM has an IPv4 or IPv6
> address the mount succeeds.
>
> Lab technician says that it might be a problem that FreeBSD nfsd
> rejects TCP connections from ports < 1024, "... because NAT cannot do
> that automatically... " (yay, cryptic, and then he went home...).
>
> Can anyone please elaborate this in more detail?
He might have meant the reverse. By default, the FreeBSD nfsd requires
that a client use a reserved port# (which is < 1024).

If that is the problem, you can do the following:
- edit /etc/rc.conf and put a line in it like
nfs_reserved_port_only="NO"
and then
# sysctl vfs.nfsd.nfs_privport=0
- to change it immediately, without rebooting the server

There are a few situations where requiring a reserved port#
improves security, but it is mostly bunk. However, FreeBSD
doesn't like defaults to change (it's referred to as a POLA
violation), so the default remains "require it".

rick

>
> Lionel
>