In order to use SSH along Git, you need to configure Git in Virtual DataPort Server and create SSH keys between the machine where Virtual DataPort Servers are and the GitLab machine. Only the RSA algorithm is supported by Virtual DataPort.
If you can SSH from the Virtual DataPort Server to the GitLab machine without a password, then the VDP Server should be able to from the VCS configuration in Denodo.
To add the RSA SSH key to your known_hosts file on the VDP server, run this command:
ssh -o HostKeyAlgorithms=ssh-rsa,ssh-dss gitlab.hostname.com
where **gitlab.hostname.com** is your GitLab server hostname.
Hope this helps!