Create RSA and DSA Keys for SSH:-

Private and public RSA keys can be generated on Unix based systems (such as Linux and FreeBSD) to provide greater security when logging into a server using SSH.

At First system side:-

# ssh-keygen -t rsa

# /root/.ssh

-rw-------. 1 root root 1675 May 12 02:04 id_rsa

-rw-r--r--. 1 root root  403 May 12 02:04 id_rsa.pub

# ssh-keygen -t dsa

# /root/.ssh

-rw-------. 1 root root  668 May 12 02:05 id_dsa

-rw-r--r--. 1 root root  611 May 12 02:05 id_dsa.pub

At second system side:-

# ssh-keygen -t rsa

# cd /root/.ssh

# vi authorized_keys [COPY THE SYSTEM ONE "ID_RSA.PUB" KEY AND PAST INSIDE THE FILE]