Your comments

That's a good idea, Polr URL Shortener is also known to work as well, it's a bit more polished. 

I don't think that is an option for the built in link sharing, at least not to free users if it does exist.

Ya pretty much, it's a work around for free users like myself. It was a decent compromise for me and has worked well. I am the only user of my FileRun, but you can still share a user's stuff this way and still edit, download, upload, etc in FileRun itself. This then gives the option to IP restrict different stuff in the web server itself.

The work around I am explaining has nothing to do with FileRun or it's configuration, forget about it for a second and all you want to do is share a folder IN the FileRun user's dir via IIS and then IP restrict in IIS.

The host os should not really matter, you just have to figure out how you share a folder in IIS and the IP restrict that folder.

The internal link sharing has nothing to do with this setup, it is totally outside of the filerun config. The way I am explaining would be = filerun (example above) is how they access the dir that is IP restricted in nginx.

Shouldn't matter my FileRun lives in /usr/local/www/filerun and my user data is in /var/db/filerun/vectr0n. I just use /var/db/filerun/vectr0n/whateverfolder in nginx with allow/deny to allow IP restricted access to that folder.

I haven't touched Windows in over 10 years now, so I am no help with IIS, but the same logic should apply.

Works perfectly fine here, I have over 20 folders shared this way and nginx does the access checking.

All I do with the free version is add a location block to nginx w/ allow/deny to the dir you want to be ip restricted. If you use apache I am sure the same can be done.

 location /pvt {
include conf.d/access.conf;
alias /var/db/filerun/vectr0n/pvt;
autoindex on;
try_files $uri $uri/ =404;