How to connect from a server to the north by key without copying the keys to the north?

Question

SSH

It turns out to walk north along the keys. It was necessary to synchronize data from one (A) to another (B) rsync using keys without passwords. What is the easiest way to do this without copying the keys to north A ? How do you do it?

Answer 1

ssh-agent + ssh-add ~/.ssh/id_rsa forwards the key to server A c from which you can later connect to server B, C, D. It's just a little dreary, I thought someone knows / uses a simpler way ..

Answer 2

without copying keys to north A

Easy, copy the keys of server A to server B.