# [step 1] create a ssh-proxy
  ssh -D 9999 -qCN user@server.net

# [step 2] make git connect through the ssh-proxy
  # [current script only]
  export GIT_SSH_COMMAND='ssh -o ProxyCommand="connect -S 127.0.0.1:9999 %h %p"'
  # OR [git global setting]
  git config --global core.sshCommand 'ssh -o ProxyCommand="connect -S 127.0.0.1:9999 %h %p"'
  # OR [one-time only use]
  git clone -c=core.sshCommand 'ssh -o ProxyCommand="connect -S 127.0.0.1:9999 %h %p"' git@github.com:user/repo.git
  # OR [current repository use only]
  git config core.sshCommand 'ssh -o ProxyCommand="connect -S 127.0.0.1:9999 %h %p"'