[Openswan Users] Kerberos authentication fails in openswan to Linsys tunnel [OT]

John A. Sullivan III jsullivan at opensourcedevel.com
Fri Dec 2 22:50:13 CET 2005

Strange.  This had a subject when I originally sent it.  Somehow, it was
stripped off - John

On Fri, 2005-12-02 at 22:26 -0500, John A. Sullivan III wrote:
> We've been struggling to get a client who wanted to use the native
> Microsoft IPSec stack managed through the linsys front end
> (http://sourceforge.net/projects/lsipsectool).  The tunnel worked great
> but windows kerberos authentication usually failed.  To our great
> surprise, we found out the Microsoft excepts Kerberos traffic from an
> IPSec tunnel by default.  We need a registry hack to change the default
> behavior as follows:
> 1. Start Registry Editor (Regedt32.exe).
> 2. Click the following registry key:
> 3. On the Edit menu, click Add Value, and then add the following value:
> Value Name: NoDefaultExempt (note that this name is case sensitive)
> Data Type: REG_DWORD
> Data Value: 0 or 1
> • 0: Default exemptions apply (default)
> • 1: RSVP and Kerberos are not exempted (only IKE, Multicast, and
> Broadcast are exempted)
> We need to set it to "1".  There is also a value of "2" for XP which
> allows broadcast and multicast packets to be tunneled.
> We also needed to use the overridemtu value to accommodate PPPoE
> Ethernet connections using NAT-T.  We weren't sure what size to set it
> to.  It seems that the ESP header size changes depending on the
> encryption algorithm (someone please correct me if I'm wrong) so we set
> it to 1400 to accommodate any algorithm.  We could probably have
> squeezed another six to 22 bytes out of it but weren't sure.
> Finally, we're struggling with the Microsoft network browsing nightmare.
> We are using WINS but, the windows clients do not appear to be querying
> the WINS servers even if we force them to p nodes.  We'll post that when
> we resolve it in hopes that someone else struggling to use Openswan and
> linsys this way will not have to reinvent the wheel.  If anyone can
> guide us on the browsing issue, we'd appreciate it.  We are suspecting
> it has to do either with needing to enable file and print sharing on the
> clients or forcing them to not be browse list servers.  Thanks - John
John A. Sullivan III
Open Source Development Corporation
+1 207-985-7880
jsullivan at opensourcedevel.com

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