[OpenAFS-devel] Multiple clients behind NAT

[Jeffrey Altman]

This is a cryptographically signed message in MIME format.

--------------ms090606000008070903060905
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit

OpenAFS has certainly had its struggles with clients behind NATs.
With the 1.4.2 OpenAFS file server I believe that all of these
troubles are behind us.  The performance of clients behind NATs
has been successively improved with each of the 1.4.x releases.

The OpenAFS 1.2.x file servers will happily communicate with clients
behind NATs although the file servers often get multiple clients
confused because it is unable to track the clients by both IP address
and port number.

One of the features of most NAT solutions is that the NAT will
map external port numbers to internal address/port values.  If your
NAT configuration is failing to do this, then you will have trouble
with many applications.

Jeffrey Altman

Ethan Tira-Thompson wrote:
> I have a setup where I have a OpenAFS client behind a NAT box (linux
> running iptables), and the NAT box itself is also an AFS client (it's
> more than *just* a NAT box).  As far as I can tell, this is a problem
> because both clients use the port 7001 for their outgoing requests, and
> so when reply packets come back to that port, the NAT is unable to
> determine which packets to keep and which to forward on. (or more
> generally, which packets to send to which client)
> 
> Back in 2001, there was a message regarding this issue:
>    http://www.openafs.org/pipermail/openafs-info/2001-January/000195.html
> ...in particular, this section:
>> Rx presently requires that anything that wants to be a server pick a
>> port number up front.  I'll be submitting patches later this week that
>> allow a server to be started on the "random" port assigned when
>> rx_Init(0) is called, which will allow user-mode RXAFS clients that
>> use randomly-selected ports.
> Was this patch ever integrated?  Since all outgoing communication
> appears to be from port 7001, I don't think so.
> 
> I'm not a huge nat/iptables expert, so perhaps I'm missing something. 
> I'm guessing there's a way to tell iptables to specifically watch for
> port 7001 from the each client, and remap those to another unique port
> when forwarding to the public interface so it can tell the replies to
> client's messages apart.  Would that work?  (I believe that's the
> suggested workaround in the quoted message)
> 
> Is that necessary to manually configure though, or should there be some
> smartness to do that automatically already (e.g. what would happen if
> two NAT'd machines try to send from the same source port out to the same
> host using TCP?  Does the NAT box just drop one of their connections, or
> does it remap one of their ports on the public interface?  Would it be
> smart enough to do that with UDP?)
> 
> thanks,
>   -ethan
> 
> PS On another topic, it would be nice to have more complete
> documentation for afsd options, e.g. the afsd.options file -- the admin
> guide (http://openafs.org/pages/doc/AdminGuide/auagd015.htm#HDRWQ391)
> does a pretty good with the cache options, but completely neglects
> discussion of many other parameters, such as -fakestat{-all}, stat,
> daemons, volumes, etc.   Some of these are mentioned on other sites'
> pages, but there should be some central documentation that lists all of
> the parameters.

--------------ms090606000008070903060905
Content-Type: application/x-pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
Content-Description: S/MIME Cryptographic Signature
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--------------ms090606000008070903060905--