Starting the Run SSH command workflow might fail with the Unable to execute command InternalError: Algorithm negotiation fail error.

Products

• VMware Aria Suite

Issue/Introduction

When you connect to a server, you must provide a list of algorithms. During the key exchange with the server, one of the algorithms is selected by a negotiation process. If there is no valid algorithm, the server rejects the connection with an error. For this reason, if you try to start the Run SSH Command workflow on Orchestrator server 5.1.x, you might receive an error Unable to execute command InternalError: Algorithm negotiation fail.

Environment

VMware vCenter Orchestrator 5.1.x

Resolution

To solve this problem, you must update the SSH plug-in. If you cannot update the SSH plug-in, edit the Run SSH Command workflow to add information about valid algorithms.

To edit the Run SSH Command workflow

1. In the Orchestrator client, make a copy of the Run SSH Command workflow.

2. Right-click the newly created workflow and select Edit.

3. Click the Schema tab in the workflows editor.

4. Select the Edit the Execute SSH command scripting element and click on its Scripting tab.

5. Add information about valid algorithms under the var session = new SSHSession(hostName,username); statement. For example:

var session = new SSHSession(hostName,username);

session.setInfo("cipher.s2c", "aes128-cbc,aes256-cbc,3des-cbc,blowfish-cbc,aes128-ctr,aes192-ctr,aes256-ctr");
session.setInfo("cipher.c2s", "aes128-cbc,aes256-cbc,3des-cbc,blowfish-cbc,aes128-ctr,aes192-ctr,aes256-ctr");
...

3. Run the newly created workflow.

NOTE This example is environment-specific and might not work for all SSH servers.