>>> On Thu, Jan 17, 2008 at  3:18 PM, in message
<[EMAIL PROTECTED]>, "McKown,
John" <[EMAIL PROTECTED]> wrote: 
-snip-
> What is an "unsecured port"? Do you mean a port <1024? What does it
> matter?

Loosely speaking, unprivileged ports, which are *above* 1024, because anyone 
can bind to them, not just processes running as UID 0.  The NFS server used by 
Linux cares because the authors thought it would be a good idea to only accept 
incoming connections that originated on a privileged port (by default).  By 
doing that, they can (perhaps foolishly, perhaps not) assume that the incoming 
connection is from a non-malicious source.  Connections coming in from ports > 
1024 could be initiated by anybody (from any IP address via IP spoofing), 
including crackers intent on subverting your NFS server, and then your entire 
system.

> In any case, to answer your question:

None of which is really going to help him, since he needs to force the z/OS NFS 
*client* to send its request out on a port < 1024, regardless of what port it 
is going to on the Linux system.  In my case, I very vaguely remember seeing 
this before, but I don't recall if it even involved z/OS NFS or not.


Mark Post

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