Is Apache Knox Gateway compatible with Cloudera 4.5?

Firstly, Apache Knox is a way to provide security at the perimeter of your cluster for REST API access. It is not a replacement for kerberos security within the Hadoop cluster when that is truly warranted. It continues to complement the kerberos enabled cluster as well by extending the reach of REST APIs into the enterprise. It also provides some additional identity solution integrations for end user access.

If what you want is real Hadoop security then you need to look to the Hadoop kerberos deployment options.

Now, as for knox/CDH compatibility...

The supported versions of service components for Knox 0.4.0 do not map well to the CDH 4.5 release unfortunately. It looks as though even the 0.3.0 releases are newer than CDH 4.5.

CDH 5.0 seems to line up better though HBase is still lagging behind. from what I see here - I can only assume that is accurate.

My suggestion would be to try Apache Knox against CDH 5 and engage the knox community with any difficulties - there may be work arounds that we can help with. Depending on your REST needs - there may be enough alignment to get what you need.