helmet-crossdomain

X-Permitted-Cross-Domain-Policies middleware
============================================

The X-Permitted-Cross-Domain-Policies header tells some web clients (like Adobe Flash or Adobe Acrobat) your domain's policy for loading cross-domain content. See the description on OWASP for more.

Usage:

``javascript
const crossdomain = require('helmet-crossdomain')

// Sets X-Permitted-Cross-Domain-Policies: none
app.use(crossdomain())

// You can use any of the following values:
app.use(crossdomain({ permittedPolicies: 'none' }))
app.use(crossdomain({ permittedPolicies: 'master-only' }))
app.use(crossdomain({ permittedPolicies: 'by-content-type' }))
app.use(crossdomain({ permittedPolicies: 'all' }))
`

The by-ftp-type` is not currently supported. Please open an issue or pull request if you desire this feature!

If you don't expect Adobe products to load data from your site, you get a minor security benefit by adding this header.