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<== Date ==> <== Thread ==>

Subject: Re: Gateways and IOC UAG security: does username to relayed with request?
From: Ralph Lange <Ralph.Lange@bessy.de>
To: "Martin L. Smith" <mls@aps.anl.gov>, Carl Schumann <schumann@fnal.gov>
Cc: tech-talk@aps.anl.gov
Date: Wed, 24 Mar 2010 13:32:44 -0400
Correct. This is the right way to achieve this behavior.

Background:

In Channel Access, user and host credentials are checked once, when the connection is made.
The Gateway acts as a proxy: it does not create a new connection when an outside client connects, but fans out the monitor updates from the IOC to its outside clients. The IOC just sees one connection: from the Gateway, with the Gateway's user and host.


That is why any access security based on the credentials of the outside clients must be done in the Gateway. The Access Security mechanism and its configuration are the same as on the IOC, but the regular expressions in the Gateway's PV list make assigning ASGs to PVs usually easier than on the IOC, as you don't have to repeat the ASG for every record instance.

Cheers,
Ralph


On Wed 24 Mar 2010 12:50:58 Martin L. Smith wrote:
Hi Carl,

I do this kind of thing extensively and quite routinely.
The user name making the request to the GW does not get passed through to the
other subnet. Instead the user that started the PV gateway process I believe is
the one that the IOC sees. I use a second layer of Access Security in the GW to
access PVs in the IOC.


In my gateway.starter file I have included in the command to start the GW
-gid 55 -uid 265 -server & This I believe will start the GW under the given gid
and uid which is what the IOC sees I think .... at least in my case. Then you
need to allow users (UAG) from the requesting subnet write access to the ASG in
the IOC ... at least this is how I do it.


Then in the IOC you must specifically allow write access from the GW uid in your
access security file.


I can send you an example if you would like.

Regards,
Marty

Carl Schumann wrote:
Hi,

We have an IOC that only permits writes from a subset of users. The IOC implements this security using UAG security and it works as expected for applications running on the IOC's subnet. Applications that are not on that IOC's subnet must access it through a gateway. These off the subnet applications can not make any settings even for users that are in the permitted subset. This has also been verified using cainfo.

Does the username of the user running the application make it through the gateway to the IOC? Our guess is no, because the gateway permissions are wide-open and writes to other IOC's without UAG security work fine. How should this kind of issue be handled? I know there is a -uid command line option but single uid will be correct for all users.

Thanks,
Carl Schumann

References:
Gateways and IOC UAG security: does username to relayed with request? Carl Schumann
Re: Gateways and IOC UAG security: does username to relayed with request? Martin L. Smith

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