To retrieve resources behind the firewall, one solution is to connect to a public server first as a middle man, and then via the server to reach the resources. The solution is to establish a ssh tunnel.
One can use a command line like
ssh -L xxx (google to see details).
However we use a jsch library to (build a java program and then) create a simple bash file.
I have prepared a ssh.jar. To use it, type
java -jar ssh.jar local_port:ssh_server remote_server:remote_port.
By the way, we can use
lsof -i tcp:'port_no' to see the the port information, e.g.,
lsof -i tcp:9001.