Cant SSH from my mac computer: ssh_exchange_identification
Most of the time it is a server side problem, so check your Raspberry Pi.

Majority of GNU/Linux distributions have /var/log/secure, you can find more data about why connection is closed.

Also check /etc/hosts.deny and /etc/hosts.allow if they are maybe blocking the access. Quick fix can be running this command in shell:

echo 'SSHD: ALL' &gt;&gt; /etc/hosts.allow


Some additional solutions that you can check can be found here http://www.linuxquestions.org/questions/linux-software-2/ssh_exchange_identification-connection-closed-by-remote-host-103423/