Setting up REST post request
As I still ran into a lot of 403 errors, I'll summarize my overall solution (Drupal 8.0.1).
Setup and configuration
Enable all core web services modules (HAL, HTTP Basic Authentication, RESTful Web Services, Serialization). Enable the relevant permissions of RESTful Web Services and for creating the relevant Nodes.
Get a CSRF token
GET http://your-drupal8/rest/session/token
POST to create a new node
POST http://your-drupal8/entity/node?_format=hal+json
Note that the URL for POST seems to be /entity/node rather than /node.
Headers
Authorization: Basic QWRt...
X-CSRF-Token: zCf...

Data
{
&quot;title&quot;: [
  { &quot;value&quot;: &quot;atest2&quot; }
],
&quot;type&quot;: [
  { &quot;target_id&quot;: &quot;article&quot; }
],
&quot;_links&quot;: {
  &quot;type&quot;: { &quot;href&quot;: &quot;http://your-drupal8/rest/type/node/article&quot; }
}
}