Add extension Remote-SSH to vscode.
https://code.visualstudio.com/docs/remote/ssh
Connect via basion server so that off-campus users can also connect. Add to your local computer ~/.ssh/config like this. And modify <>
Host smith-private
Hostname <smith-host>
Port 22
User <smith-user-name>
ProxyCommand ssh -Y -W %h:%p smith-bastion
ForwardX11 yes
ForwardX11Trusted yes
Host smith-bastion
HostName ssh-gw.eng.osaka-u.ac.jp
Port 22
User <gateway-user-name>
IdentityFile <path-to-secret-key>
ForwardAgent yes
ForwardX11 yes
ForwardX11Trusted yes
command+shiht+p in vscodeRemote-SSH: connect to Hostsmith-private