UDP/TCP problem in cross-realm authentication

miguel.sanders@arcelormittal.com miguel.sanders at arcelormittal.com
Fri May 22 05:14:01 EDT 2009

Moreover, do you even see the KRB5KRB_ERR_RESPONSE_TOO_BIG reply from the KDC?

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-----Oorspronkelijk bericht-----
Van: kerberos-bounces at mit.edu [mailto:kerberos-bounces at mit.edu] Namens Bjoern Tore Sund
Verzonden: vrijdag 22 mei 2009 11:05
Aan: kerberos at mit.edu
Onderwerp: UDP/TCP problem in cross-realm authentication

We have linux clients in an MIT Kerberos realm (1.6.3), Windows XP SP3 clients in AD and  two-way trust configured.  Accessing AD resources from Linux clients work perfectly.

Accessing resources in the MIT Kerberos realm from Windows fails more often than not.  Lots of packet sniffing shows fragmented UDP packets which the unix server isn't able to reassemble.  So, in accordance with
http://support.microsoft.com/kb/244474 we've set HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa\
Kerberos\Parameters\MaxPacketSize to 1 on the XP clients.  Still no go, they never try TCP (again sniffing both on the XP client and the unix kerberos server) but go straight for TCP.  TCP is working on the unix kerberos server, the linux clients are happily using it.  Have anyone seen MaxPacketSize fail to have effect before?  Any ideas on how to trace this further?

Bjørn Tore Sund       Phone: 555-84894   Email:   bjorn.sund at it.uib.no
IT department         VIP:   81724       Support: http://bs.uib.no
Univ. of Bergen

When in fear and when in doubt, run in circles, scream and shout.
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