I just got an Rpi 3 model B and installed raspbian on my SD card. (in 2017) then I powered it on for the first time and connected it to the ethernet. I found its IP address and tried to ping it. Ping works fine, However, when I tried to SSH it(ssh firstname.lastname@example.org), it says "ssh xxx.xxx.x.xx port 22: connection refused" Do I have to use a screen and keyboard & mouse to set it up? or if there's any way to fix that?
According to the Official Documentation
ssh is disabled by Default on Raspbian Jessie.
You will need a Screen and Keyboard to enable
Reboot your Pi