You can use admin.savvii.com to restrict access to your website via sFTP to your approved IP addresses. Although sFTP is very secure in itself, this is how you add extra security. You can set this up as follows:
When you are logged in to admin.savvii.com, click on Manage -> User to go to the appropriate tab. There you will find the settings for IP whitelisting under the section Access restriction.
By default there is no whitelist active. Here you can see the whitelist, the IP address you are working from or add another IP address to the whitelist.
When you add an IP address to the whitelist, you can no longer connect from other addresses. It takes about 15 minutes for the changes to take effect. If you are in a new location and therefore do not have access, you can always log in to admin.savvii.com and add your current IP address there.