dat is a peer-to-peer system for distributing large files, such as operating system images or scientific data sets. The datserver app creates an instance of hypercored, which can then be used to host dat files on your server, ensuring that they're always available to download.
dat is preferable to older ways of distributing files, such as ftp, because files are content addressable and can be seeded on multiple machines to provide greater speed and robustness. It also works nicely with the Beaker browser.
ssh into the system with:
ssh myusername@mydomain.com -p 2222
Select Administrator controls then Add/Remove Apps then datserver.
Once installed you can select Administrator controls then App Settings then datserver and add dat links to be served.