[AG-TECH] Access Grid 3.0 beta1 available !

[Nagykaldi, Zsolt F. (HSC)]

2 comments:
 
1) Win XP SP2 indeed self-configures the client machine firewall for the AG Toolkit. The problem is that most Universities have a group policy to overtake individual firewall control (usually they turn it off) when the PC is connected to the local network. This renders local settings void and only central settings count.
2) Interestingly, RAT almost always works (apart when clients have "local " IPs assigned by PIX, where port forwarding or dedicated IP address assignment help only), but VIC almost never works just by installing the Toolkit behind regular firewalls. This tells me that in the case of VIC, the connection is actually initiated by the server (???) and since many networks specifically block INBOUND connections, VIC can not receive incoming video, while RAT is fine (client initiates connection??). This would explain why in many cases parties can talk and may be visible on one side, but can not receive video on the other (ominous "waiting for video..." message). I wonder whether something could be done regarding this specific problem (i.e. can VIC work like RAT in this regard).
 
Zsolt
 
 
_ _ _
 
Zsolt Nagykaldi, PhD
Research Associate, Clinical IT Specialist
University Of Oklahoma Health Sciences Center
Department Of Family And Preventive Medicine
Oklahoma Center For Family Medicine Research
 
900 NE 10th Street
Oklahoma City, OK 73104
Phone: (405) 271-8000 Ext.:1-32212
Fax:     (405) 271-1682

________________________________

From: Piers O'Hanlon [mailto:p.ohanlon at cs.ucl.ac.uk]
Sent: Mon 1/30/2006 12:21 PM
To: michael.daw at manchester.ac.uk
Cc: Nagykaldi, Zsolt F. (HSC); ag-tech; Socrates Varakliotis
Subject: Re: [AG-TECH] Access Grid 3.0 beta1 available !



Hi Mike (and others),

> We discussed doing this as part of the SUMOVER project workshop in
> November. This project is updating vic and rat at UCL, mainly for the
> AG community. I can't remember where it was on the priority list,
> though...

I guess there's a couple of issues here - There's port selection, and
there's firewall config.
- As mentioned by others the media port ranges are controlled by the AG
server's config - these can be taken down to narrower ranges. There's
shouldn't be too much of an issue with multicast venue address clashing
if the 233/8 GLOP addressing is used by the servers.

- Secondly the firewall interaction then depends on which platform AG
client is running on - For those lucky folk running WinXP-SP2 I
understand that AG will automatically configure the windows firewall to
let AG traffic pass (could possibly explain lack connectivity in one
previous email if things go wrong?). If you're not running Windows
Firewall then you're probably back to manual FW config. If you're
running Linux then you'll need to open some holes in your firewall
(iptables/ipchains etc) manually.

I should mention that most of this is out of scope of the media tools
themselves as UDP port selection isn't generally done by the tools
themselves. The one caveat is that vic does normally allow the OS to
choose the source port when it sends video packets, though this doesn't
usually matter if the firewall is appropriately configured. If needs be
we could add an option to enable source port selection, or 'symmetric'
ports usage.

Piers.

> 
> More information (though sparse!):
> http://www.cs.ucl.ac.uk/research/sumover/

It has been updated today with more info.

Piers.

> 
> Perhaps one of the team could enlighten us...?!
>
>     ------------------------------------------------------------------------
>     *From:* owner-ag-tech at mcs.anl.gov
>     [mailto:owner-ag-tech at mcs.anl.gov] *On Behalf Of *Nagykaldi, Zsolt
>     F. (HSC)
>     *Sent:* 30 January 2006 15:19
>     *To:* ag-tech
>     *Subject:* RE: [AG-TECH] Access Grid 3.0 beta1 available !
>
>     
>     It seems that most practical problems during implementation come
>     from firewall issues. Are you guys planning to (at least) narrow
>     the UDP port range for VIC and RAT, or maybe (in my dreams) tunnel
>     all audio/video traffic through a few number of ports that are
>     usually open? I have been networking with a lot of people who are
>     desperate to set up their nodes and they hit a brick wall every
>     time it comes to push changes through their IT departments, who
>     are freaking out about the idea of opening ports in such a wide
>     range. More and more people would like to use the system via PIGs
>     and not necessarily big institutional nodes that require weeks, if
>     not months of negotiations and arm-twisting each time a new client
>     is added at a new location. (The AG Connector would be really
>     helpful, except it causes an ominous looping drop of all
>     audio-video connections, as it has been reported before, and it is
>     very unreliable). Extra features in v3.0 are nice, but I truly
>     believe that the firewall/ports issue is the most significant
>     barrier to wider adoption of the Toolkit.
>     
>     
>     Zsolt
>     
>     _ _ _
>     
>     Zsolt Nagykaldi, PhD
>     Research Associate, Clinical IT Specialist
>     University Of Oklahoma Health Sciences Center
>     Department Of Family And Preventive Medicine
>     Oklahoma Center For Family Medicine Research
>     
>     900 NE 10th Street
>     Oklahoma City, OK 73104
>     Phone: (405) 271-8000 Ext.:1-32212
>     Fax:     (405) 271-1682
>




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