This video demonstrates how simple it can be to setup a SFTP server using CentOS 7 with a Chroot user jail so that users cannot see each others folders or the underlying filesystem.
PS. I used netstat to check is the firewall is open on port 22, this is not a necessary step but if you want to do it on CentOS 7+ you will need to install the net-tools package first. You can do that like so:
sudo yum install net-tools
This is extremely handy as it works perfectly and for the low price of free it’s cheaper than the M$ alternatives that either don’t work reliably or cost hundreds of dollars.