"You don't need some big fancy expensive groupware suite for
simple file sharing; just set up a good stout Linux server with
WebDav and be done with it. No muss, no fuss.
"The WebDAV protocol allows you to store and share files via
HTTP; effectively, where HTTP is usually read-only, WebDAV allows
writing as well. As well as accessing documents, you can (with
suitable permissions) edit and re-upload them. You can think of it
as a networked file-system run over HTTP; or as a way of supporting
long-distance collaboration on files. The protocol supports locking
and versioning information, so once you've accessed the WebDAV
folder (see below), you can edit files without risking overwriting
other people's edits. These days there are more and more ways
available to undertake online collaboration, but WebDAV is still a
useful and straightforward way to share files, especially as it's
supported by plenty of software at both server and client end.
"Unlike FTP, HTTP provides strong authentication and encryption,
as well as caching and proxy support – and because WebDAV
works over HTTP, this means that WebDAV gets all of that for free.
SSH would be another option, but SSH is a bit more limited in terms
of moving files around, and certainly doesn't have the same sort of
client support and tools available."