In the menu go to Connection -> SSH -> Tunnels
- Select Dynamic below destination
- Put 1024 as source port
- Click on Add
Login.
ssh -D 1024 my-user@mybastion-server
In Advanced options, select the network tab and click on Connection configuration.
- Select "Porxy manual configuration"
- In SOCKS, enter localhost and in port 1024
- Select SOCKS v4
Click on OK.
You should be able to connect to any host behind your bastion in firefox