Firewall issues while creating an external content type

Question

I'm trying to create an external content type using SP designer in an SP2013 farm. The SP servers have access to the SQL server I need, and I have access to the SP servers from the VM I'm running the designer on, via VPN. However I don't have access to the database from this environment directly. I was wondering how the designer sets up the db connection exactly. Is it going through sharepoint if I'm using SSS, or do I actually need access to the database in order to initially set up the db connection while creating the external content type?

I've been trying to find this info with no luck for a while. I wonder if someone knows the answer.

Answer 1

When you use designer to connect SharePoint, it only need your machine to SharePoint WFE open connection. Then all other SharePoint related stuff done by WFE ( i.e. connecting to SQL or getting services from any app server).

For external content type, i think you have to make sure SharePoint server able to connect that sql server.

https://lightningtools.com/bcs/creating-an-external-content-type-with-sharepoint-designer-2013/

Also check this blog (i think option # 6): https://blogs.msdn.microsoft.com/uksharepoint/2013/01/21/sharepoint-2013-ports-proxies-and-protocols-an-overview-of-farm-communications/