[_msw_]

The 3 clause BSD gives all the permissions that are needed for someone to add restrictions via their own license terms.

Licenses like the GPL come with an obligation that one not add restrictions when passing the software on to others.

[jaypatelani]

So how did RedHat add restrictions on gpl code base of CentOS?

[tsimionescu]

RedHat says that you can't get future versions if you exercise your GPL freedoms. You are free to redistribute the latest version of RHEL or CentOS or whatever, including all source code for all packages in their repos. But they will never give you another version of any of their software if you do so.