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I installed a vpnc on my Linux red-hat machine version 6.3

Most of the cases vpnc work well ( connecting to gateway customers by vpnc )

But against some particular customers ( Cisco gateways ) , immediately after I activate the vpnc I get the following messages:

    vpnc: quick mode response rejected:  (ISAKMP_N_INVALID_PAYLOAD_TYPE)(1)

In this case Vpnc could not be connected

Please advice what the problem here? ,

 [root@TEST-LINUX-MACHINE /var/tmp]# vpnc
 Enter password for user@ 

Connect Banner:
| Remote access to UGG company resources is restricted to AUTHORIZED USERS!
| Company resources may only be used for the purpose of performing work-related duties.
| The user is responsible for protecting the confidentiality and integrity of the      company resources.
| Violation may cause disciplinary action.
| By clicking on "Continue" the user agrees with the rules above.

 RTNETLINK answers: File exists
 **vpnc: quick mode response rejected:  (ISAKMP_N_INVALID_PAYLOAD_TYPE)(1)**
 this means the concentrator did not like what we had to offer.

 Possible reasons are:

 * concentrator configured to require a firewall
   this locks out even Cisco clients on any platform expect windows
   which is an obvious security improvment. There is no workaround (yet).
* concentrator configured to require IP compression
   this is not yet supported by vpnc.
   Note: the Cisco Concentrator Documentation recommends against using
   compression, expect on low-bandwith (read: ISDN) links, because it
   uses much CPU-resources on the concentrator

I also try to do the follwoing

  Add the line "NAT Traversal Mode cisco-udp" in /etc/vpnc.conf


   Add the line "Local Port 10000" in /etc/vpnc.conf

But they dosent help and I still get the bad messages ( chuld not be connected by the vpnc )

Please advice where is the problem ?

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