I'm really trying to avoid using bridges if possible. Most bridging(non VPN 
bridges like AG) solutions use UDP and my users are UDP incapable :(

On OpenVPN, they don't use L2TP or PPTP but use SSL.

--



   Does OpenVPN support IPSec or PPTP?

   There are three major families of VPN implementations in wide usage today: 
SSL, IPSec, and PPTP. OpenVPN is an SSL VPN and as such is not compatible with 
IPSec, L2TP, or PPTP.

   The IPSec protocol is designed to be implemented as a modification to the IP 
stack in kernel space, and therefore each operating system requires its own 
independent implementation of IPSec.

   By contrast, OpenVPN's user-space implementation allows portability across 
operating systems and processor architectures, firewall and NAT-friendly 
operation, dynamic address support, and multiple protocol support including 
protocol bridging.

   There are advantages and disadvantages to both approaches. The principal 
advantages of OpenVPN's approach are portability, ease of configuration, and 
compatibility with NAT and dynamic addresses. The learning curve for installing 
and using OpenVPN is on par with that of other security-related daemon software 
such as ssh.

   Historically, one of IPSec's advantages has been multi-vendor support, 
though that is beginning to change as OpenVPN support is beginning to appear on 
dedicated hardware devices.

   While the PPTP protocol has the advantage of a pre-installed client base on 
Windows platforms, analysis by cryptography experts has revealed security 
vulnerabilities.


   ---



   On 10/31/06 5:20 AM, "Andrew A Rowley" <[email protected]> 
wrote:

   > Hi,
   >
   > I have often used the VPN at Manchester from various locations, mostly in 
the
   > UK.  I think this is a hardware VPN solution, so this may explain why it 
works
   > well.  It certainly allows you to use the AG bridged (our VPN network is 
not
   > multicast enabled) from behind a restrictive firewall, so long as the VPN
   > outgoing port is enabled.  I have even used this to run AG over wireless,
   > where our wireless network only allows traffic outgoing over TCP ports 80 
and
   > the VPN port.
   >
   > Regarding a software VPN, this should work if it is configured correctly, 
but
   > configuring VPNs can be quite hard.  I would think that an L2TP IPSec VPN 
with
   > IKE configuration would probably work well.  I am fairly sure that this 
sort
   > of set up would be possible with OpenVPN.
   >
   > Andrew :)
   >
   > ============================================
   > Access Grid Support Centre,
   > RSS Group,
   > Manchester Computing,
   > Kilburn Building,
   > University of Manchester,
   > Oxford Road,
   > Manchester,
   > M13 9PL,
   > UK
   > Tel: +44(0)161-275 0685
   > Email: [email protected]
   >
   >> -----Original Message-----
   >> From: [email protected] [mailto:[email protected]] On
   >> Behalf Of Many Ayromlou
   >> Sent: 30 October 2006 21:57
   >> To: Doug Baggett
   >> Cc: ag-tech
   >> Subject: Re: [AG-TECH] Using Access Grid with Ethernet Bridged OpenVPN
   >>
   >> Hi Doug,
   >>
   >> A while back I tried OpenVPN (mac client @ home behind NAT/Router---
   >>> linux server on open network) and although other stuff worked, I
   >> could not get AG going (I was not using bridged mode though.....I was
   >> using the other mode.....don't remember right now).
   >>
   >> I have since tried to run it with an L2TP type VPN (Mac notebook
   >> running osx behind NAT/Router --> Mac OSX Server on open network) and
   >> AG3 works quite well. I've been able to get somewhere near 14-16
   >> videos smoking my 6Mb dsl link. I've also tried this from behind a
   >> firewall at work (mac notebook behind a really strict firewall
   >> blocking ports 1024+ UDP/TCP ---> same mac OSX server on open
   >> network) and AG3 works fine.
   >>
   >> So to answer your question OpenVPN did not work for me and I admit it
   >> was not the same situation you're describing. L2TP worked fine behind
   >> NAT and also behind a pretty strict firewall.
   >>
   >> TTYL
   >> Many
   >> On 30-Oct-06, at 1:35 PM, Doug Baggett wrote:
   >>
   >>> Has anybody tried using Access Grid using bridged Ethernet and
   >>> OpenVPN?
   >>> (www.openvpn.net)
   >>>
   >>> OpenVPN supports TCP instead of UDP, and I have users behind
   >>> Firewalls that
   >>> restrict outbound UDP and I have a server that I could use as the
   >>> endpoint
   >>> that sits
   >>>
   >>> I know there would be a performance hit using TCP, but on a high
   >>> performance
   >>> network it would be interesting to know if anybody has given it a try.
   >>>
   >>> -Doug B
   >>> OCI/NSF
   >>>
   >>

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