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SSH is “Secure Shell”, and it’s basically an encrypted exchange of data between your computer & another. In the case of a an SSH “tunnel”, you’re not involved. The computers talk to each other, with all the security & privacy guaranteed by SSH. This article covers some solid basics, but doesn’t pretend to teach network security. Get professional help if you value your money & the business that generates it.
Typically, once an SSH tunnel is established, it is left in service the entire time. It’s never turned off (though it can be) but needs to be started every time that one (or the other) computer is rebooted.
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