VPN Tunnel Error : decrypt : mac verify failed for connection id

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Dec 3rd, 2008
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We have a site to site GRE VPN Tunnel between two 1841 routers . The following error be logged every some mintues repeatedly:

"decrypt: mac verify failed for connection id" .

But traffic folow is running without interruption.

Anybody know what is wrong regarding to this error ?


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ajagadee Wed, 12/03/2008 - 08:36
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  • Cisco Employee,


Below is the explanation on the error message.

Error Message

%CRYPTO-4-RECVD_PKT_MAC_ERR : decrypt: mac verify failed for connection id=[dec]

Explanation The MAC verify processing failed. This might be caused by the use of the wrong key by either party during the MAC calculations. This activity could be considered a hostile event.

Recommended Action Contact the peer administrator.


If the configuration looks good and traffic is flowing without interruption, then it looks like a software bug to me.



*Pls rate if it helps*

bharam Mon, 01/19/2009 - 03:47
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I have the same problem, GRE VPN tunnel between 1841 and 7206.

IOS version on the 1841 is 12.4(23) Adv IP serv., the 7206 is running 12.3(20) enterprise ipsec 3des feature set. The error message is only logged on the 1841 router.

Do you still have this problem on you routers?



bharam Wed, 01/28/2009 - 12:39
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Cisco bug ID: CSCsv43145

We have tested a few IOS versions:

With the routers running 12.4(23) and 12.4(5) error messages appear every minute.

Routers running IOS version 12.4(13f), 12.4(16b), 12.4(17b), 12.4(18c), 12.4(19b) and 12.4(21a) seems to be working fine.



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