How to give a user access only to a specific site directory?

Question

linux

There is a server.
On the Bitrix VM server on CentOS 7.
There are many sites on the server.
The freelancer needs to make an SFTP user.
so that he has access to only one site in /home/bitrix/ext_www/site.ru
And so that he cannot do anything via SSH in the shell, only work with files through some IDE and that's it.
How to implement this?

Answer 1

We use ProFTPD.
The jamb is that the scripts still work on behalf of bitrix, and he is the admin.

ftpasswd --passwd --file=/etc/ftpd.passwd --name=bxuser --uid=600 --gid=600 --home=/home/bitrix/ext_www/bitrix-site.ru/ --shell=/bin/false