What is SSH forwarding?

Question

I read a guide. It says that run the following line and forget it.

/usr/bin/ssh-add -K

I am not sure when and where I should use it.

What is SSH forwarding?

Answer 1

If you don't know why you need it, you won't need to add it to set up your ruby environment.

Note to others: this is a question relating to setting up his dev environment before people demand it is closed.

Answer 2

Here's an explanation. And another. An "illustrated" one.

Those should give you a general idea of what's going on here.

Answer 3

That seems to be a Mac OS X specific option to ssh-add. It adds identities to your OS X keychain, so that any later use will already have them handy.

This is different from other kinds of forwarding. My typical use is to do normal ssh-add with no extra options, then ssh -A to forward the agent. Meaning that if I ssh to another host through the first one, my creds are automatically passed on. Very handy.

By far your best bet is to read the manual pages for any options you see used. Ssh comes with great man pages.