Xshell Forum

MAC (message authentication code)

Last post: Monday, February 22, 2010 5:13 AM by Support, 8 reply

 
Friday, February 5, 2010 3:44 AM - fx

MAC (message authentication code)

 
Xshell 3.0 (Build 0271)
Remote server supports SSH1.
Xshell session configuration: Connection > SSH > Protocol Versions : SSH1 only

When I try connect to a server:
The MAC (Message Authentication Code) of a packet is incorrect.

MAC in SSH1?

Program Ver. : Xshell 3.0
Monday, February 8, 2010 1:00 AM - Support

Re: MAC (message authentication code)

 
This is a new problem for us too. Could you send us the following information?

1. The name and version of the SSH server
2. Encryption type
3. Can you login after getting the message?


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Technical Support
Monday, February 8, 2010 1:56 AM - fx

Re: MAC (message authentication code)

 
Connection established.
Escape character is '^@]'.
[10:44:17] Version exchange initiated...
[10:44:17] server: SSH-1.5-1.2.33
[10:44:17] client: SSH-1.5-nsssh2_3.0.0015 NetSarang Computer, Inc.
[10:44:17] SSH1 is selected.
[10:44:17] Host authentication initiated...
[10:44:17] Hostkey fingerprint:
[10:44:17] ssh-rsa 1024 [cut]
[10:44:17] Accepted.
[10:44:17] Exchanging encryption algorithm...
[10:44:17] 3des is selected.

Warning window: "The MAC (Message Authentication Code) of a packet is incorrect."
Click "OK" and...

Connection closed by foreign host.


This problem occurs only in Xshell 3.0 (Build 0271).
Previous versions was OK.
Monday, February 15, 2010 3:44 AM - fx

Re: MAC (message authentication code)

 
Any ideas?
Wednesday, February 17, 2010 11:47 PM - Support

Re: MAC (message authentication code)

 
This problem could not be duplicated in our lab. MAC warnning message is not an intended operation and will fix it soon.

Here are few things you can try:

1. Try using a different encryption algorithm: Open session properties and click on the Security menu. From the Encryption list, select one from the list other then 3des-cdc.

2. Could you try again with the previous Xshell version and see if the problem does not occur? And, if the problem does not occur, tell us the Xshell version.

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Technical Support

Thursday, February 18, 2010 12:19 AM - fx

Re: MAC (message authentication code)

 
1. I tried all and the problem still occurs.

2. Last version before Xshell 3.0 (Build 0271) was ok.
Friday, February 19, 2010 1:29 AM - Support

Re: MAC (message authentication code)

 
Here is a link to the previous build:

http://download.netsarang.com/files/xsh03000260.exe

(Build 0260)

could you try again with this version and see if the problem persists?

Thank you


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Technical Support
Friday, February 19, 2010 2:41 AM - fx

Re: MAC (message authentication code)

 
When I installed Xshell (Build 0260) on my computer the problem still occurs but... on other computer with this same OS it works fine!

I don't understand...
Monday, February 22, 2010 5:13 AM - Support

Re: MAC (message authentication code)

 
We are not sure what may cause this problem. The only thing certain at this problem is that this error can occur when checksum value is invalid while Xshell trys to decrypt received packets.

Please try the followings:

1. Open Host Key Manager (Tools > Host Key Manager) and erase all host keys
2. Create a new user account on the server
3. Connect to the server using the new user account.

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Technical Support