"Negotiation failed. The client and the server have no common key exchange algorithm."

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What does "Negotiation Failed" Mean? 

The "Negotiation Failed" message is typically encountered when remotely connecting using either FTP or proxy connections. The error message can indicate that JAMS is forcing a secure connection with an algorithm not supported by the remote server.

 

Select the Error Received to Learn More: 

 


Note: TLS 1.2 was not available in versions of JAMS before 6.4.  Its default availability may cause problems on connecting to existing servers that, prior to JAMS 6.4, used TLS 1.1 or lower.


 

"Requested Service is not implemented."

The following stack trace error may occur after a server is modified or updated:

StackTraceError.png

Troubleshooting

  1. Create a FileTransfer Execution Job and target the agent you are attempting to use.
  2. Add the JAMSSshLogLevel parameter to the Job.
  3. Set the Log Level for the parameter to "Verbose".
  4. Initiate a connection via the Job.
  5. Review the Verbose Log for available key exchange algorithms.
  6. Cross reference available key exchange methods with methods available on the client (SSH_MSG_KEXINIT Received vs Sent)
  7. Create a parameter "JAMSShKeyExchange".
  8. Specify a valid value from the list of values within the reference document.
  9. Repeat as needed for each permutation of parameters.

Need Additional Assistance?

  • Contact your System Administrator. 

 


 

"The client and the server have no common key exchange algorithm."

 

This error indicates JAMS is forcing a secure connection with an algorithm not supported by the remote server. Due to possible encryption algorithm vulnerabilities, JAMS forces a remote server to use secure ciphers only.

 

Resolving the Issue

The recommended solution to reduce vulnerabilities is to upgrade the remote server to accept more secure encryption key algorithms.


Note: JAMS can be configured to allow a smaller minimum DiffieHellman key size in the event a secure algorithm cannot be used.

This is not recommended. Contact your System Administrator before proceeding.


 

Minimum Key Size Modification

 

Versions Prior to 7.0

FileTransfer Execution Methods

  1. Go to the Job Source.
  2. From the "Source" tab, navigate to the "Minimum Key Size" field and change as shown below:

     

    V6JobFTPFileTransferKeySize.png

 

SFTP

For Workflow Jobs using any JAMS SFTP Activities, set the "MinimumDiffieHellmanKeySize" option as shown below:

WorkflowUsingSFTPActivities.png

 

Version 7 and Later

JAMSKeyMgmtGenerateKey.png

PowerShell 

Specify the "Minimum Key Size" argument using the Connect-JSFTP cmdlet:

-MinimumKeySize <Int32>

The cmdlet will set the minimum DiffieHelman key size in bytes (0 by default).

 

 


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