Slack webhook - What IP addresses should I open?

Question

We want to use Slack Webhook (outgoing Webhook) with an internal web service.

Our company is located behind the firewall, so external connections should be included in the white list.

It seems that Slack has several addresses to which it will send an API request, and they do not seem to be documented.

What IP addresses / ports should I open in my firewall (whitelist) to allow pluggable websites to connect to our internal web service?

Answer 1

An alternative would be to use a VPN tunnel service to publish your internal web server to the Internet, for example. with ngrok . I can confirm that it works with Slack (I use it every day to develop Slack), and it is also recommended as a solution for the local development environment in the Slack tutorials .