CentOS

Kindly let me know the latest openssh vesrion for centos 6, and to which version can it be upgraded from the mentioned URL.

URL: http://www.openssh.com/index.html

$ rpm -q openssh
openssh-5.3p1-123.el6_9.x86_64

The above is the latest openssh version as released by CentOS. I would recommend sticking to that version.

Please also read the backports link to discover _why_ it is this way.

https://access.redhat.com/security/updates/backporting