Connectivity has been setup from our staging environment to the third party server (endpoint of our soap clients). However, I wanted to connect locally with SOAP UI to this server, so I needed to setup an ssh tunnel with portforwarding on my macbook. I used to do this with putty on windows in the past so it took me a bit longer to figure this out.
Let's say the endpoint used from our staging environment would be "http://3rdpartyhostname/coolservice". In this case I want to listen on port 8877, and forward traffic from this port using the ssh tunnel to 3rdpartyhostname on port 80
ssh -f username@staginghostname -L 8877:3rdpartyhostname:80 -N
Now I can connect in SOAPUI to the following endpoint "http://localhost:8877/coolservice"