What is a clocking and doorway page?

yes both are black hat techniques.
If you show a different version of a page to SE and a different one to your user then it is called Cloaking.
Doorway pages are stand alone pages that are optimized for a single keyword and sometimes for a particular search engine.

Cloaking is a search engine optimization (SEO) technique in which the content presented to the search engine spider is different from that presented to the user's browser. This is done by delivering content based on the IP addresses or the User-Agent HTTP header of the user requesting the page. When a user is identified as a search engine spider, a server-side script delivers a different version of the web page, one that contains content not present on the visible page, or that is present but not searchable. The purpose of cloaking is sometimes to deceive search engines so they display the page when it would not otherwise be displayed (black hat SEO).

Cloaking is a black-hat SEO technique. It means delivering one web page to search engines and completely different web page to visitors. Search engines index a web page and rank it higher in the SERPs according to META tags, titles and other SEO techniques. When people open a cloaked web page, they do not get what they were looking for.

Doorway pages are typically large sets of poor-quality pages where each page is optimized for a specific keyword or phrase.
Since both are intended to deceive search engines, they are termed as black-hat.

CLOAKING
It is used to mislead spiders about the actual content of a site.

DOORWAY PAGES
It uses a single page, stuffed with keywords, to get higher rankings with the search engines. Also known as "gateway page" or "bridge page".