SSH login to host1 and bind local port number to forward through the ssh tunnel to host2 on the specified port.
ssh -L <local_port>:<host2>:<host2_port> <user>@<host1>Then just connect to the localhost 127.0.0.1:<port> so network packets sent to that local port will tunnel through
SSH and be forwarded on the other side from the ssh server on that same port.
WARNING: you probably don't want to use -R because that would bind the port on the remote host1 in a way that
anybody could connect to it - it wouldn't be protected inside an SSH tunnel on your local machine, and nor would
your network packets between your machine and host1.
I used to use this -L tunnel to my home Subversion server in the 2000s to commit my home directory configs and
personal scripts for my l33t Gentoo workstation & laptop. Thankfully the superior Git and remote working both
kill the need for such tunnelling just to commit.
See HTTP Proxying for how to standard web application clients to use proxies including
programming build tools and CLIs which are really Rest API clients like kubectl.
On GCP, you may tunnel through a bastion host like this:
(exclude googleapis.com otherwise gcloud CLI won't be able to connect to Google since it is the tunnel which is
not up yet)
export no_proxy="googleapis.com"
export NO_PROXY="$no_proxy"
export PROJECT_PROXY_PORT=8888
gcloud compute ssh bastion-vm -- -4 -N \
-L "$PROJECT_PROXY_PORT:127.0.0.1:$PROJECT_PROXY_PORT" \
-o "ExitOnForwardFailure yes" \
-o "ServerAliveInterval 10"
export https_proxy="http://localhost:$PROJECT_PROXY_PORT"
export HTTPS_PROXY="$https_proxy"