Re: iSCSI CONNECT message

["Jim Hafner/Almaden/IBM" <hafner@almaden.ibm.com>]

Folks,

Let's see if I can handle a bunch of these questions at once.  I'll admit
upfront that I'm not the most knowledgeable about how the IP network works,
how DNS works, how tunnelling works, etc.  As a consequence, I may be using
terms well-known in the network community in the wrong way.  Please correct
me if I am.

Definition: I'm using the term gateway here to mean any device (proxy,
etc.) with the following properites:
1) it sits between an initiator and a target (an implementation of a proxy
or any other sort of firewall)
2) it obscures the ipname/address of the target on its back-side from the
initiator on the front-side.
3) it is NOT an iSCSI target device; it is a device that enables connecting
two iSCSI devices
(in effect, a gateway is a device that must provide some sort of
tunnelling).  Or is "intermediary" a better term here?

Tunneling:  As Costa said, the only standardized tunnelling mechanism
defined (AFAIK) is in specific protocols like the HTTP GET URL protocol.
As I mentioned in my note, I'm suggesting that perhaps an analogous
function is required here.

Use of DNS: there may be security concerns here (about DNS itself).  But
this also assumes that every iSCSI target has a "public" ipname (or perhaps
ipname:port combo).This may or may not be the case (correct?) if the
controller lives deep in the bowels of some private network.

If the controller has a public IPname, then the normal mechanisms for
connecting to it should work (even through gateways as described by
Joshua).  In my proposal, the CONNECT message effectively gets delivered
directly to the target in the first step.

Is this the same as the login?  To me, the login is an initiator to target
operation, to validate the iSCSI to iSCSI layer connection end-to-end (once
the pipe is open for them to talk to each other).  iSCSI security may be
completely independent of the link security (e.g., that the gateway might
want to impose).  The iSCSI login security involves a context that is only
relevant to the two end points as iSCSI entities, not as TCP/IP entities
(i.e., at a different layer).  The link security is potentially independent
from the iSCSI security context and is a function of the two ends of an
intermediary link (as TCP or IP entities).  The CONNECT message then is the
instruction to the intermediary to request it's tunnelling services.
This gets to one of David's concerns about tunnel autoconfig.  My third
option (my favorite) for security in the CONNECT was effectivly leveraging
whatever tunneling autoconfig policies are in place between the two
endpoints of a hop (in the picture below, G1 and G2 may have their own
policies, which I assume they impose on each other, independent, perhaps,
of the type of traffic).

Julo's Topology(a):  I---G1---G2---G3---T

This is exactly the topology that Daniel and I discussed and the CONNECT
message was supposed to enable.  If this is "of little interest", then I
don't see the point of the CONNECT, either.  It may be that a gateway is
just a passthru or a proxy or any other mechanism that the gateway utilizes
in order to provide the services (QoS, security, etc.) that motivated the
placement of that gateway in that spot in the first place!

David also mentioned an issue about QoS and such.  If I'm a gateway doing
all this obsuring, then perhaps I'd like to have policies for QoS as well.
Whether they are blind to the type of traffic (iSCSI or http or ...), is a
different issue.

In short, I think I can summarize the issues:
A) if an initiator can ALWAYS open a connection to a target through normal
TCP/IP mechanisms, then there is no need for my proposal. (I didn't think
this was necessarily possible).  Additionally, this assumption implies that
target naming is pure and simply an ipname:port and nothing more (that is,
I don't need URLs or any other complicated naming scheme).
B) if NOT, then my proposal defines a means whereby that initiatial
connection can get established, in order that the rest of the iSCSI process
can begin. I think you need a two-part naming mechanism in this case.  If
one was enough, then option A holds.

Did I miss anybody's questions?  Am I completely off base here?  Can
somebody say whether (A) holds?  Does (A) hold with the requisite security
requirements (or is that a separate issue)?

Jim Hafner