Private networks-?

[Julia.Ru]

Do you know anything about the so-called "private networks"?

The point is, a certain website that specializes on them, got interested in my site (my other project devoted to learning English). Later on, I noticed traffic coming to me from websites that have nothing to do with studying English (sites about glass packets, building materials, etc.). Then an empty folder with a strange title (mainly question marks) appeared in the folder "httpdocs".

I've read some information about private networks, but I haven't found the info about what they can do to my site and whether they may be harmful.

[wstein]

Sounds like SPAM. The mysterious folder may be a sign of hacking or an error on your server.

A private network is like any other network but access is limited to certain people. Sometimes there is a gateway to a ‘public’ network (like the internet) but not always. They are most common within companies or institutions.

[Julia.Ru]

Perhaps, in English it should really sound different, but I'm not sure what the English for it will be.
I got it, what you're talking about is a local network, but it's another story with these "private networks".
From what I've read on their website, they search for sites with genuine content and good traffic and then offer their clients to put links on such sites (like, on 500 sites from their database). It has to do with SEO, links exchange and all that. Meaning, "private network of websites-satellites"