Many users have expressed a desire to be able to whitelist Blitline postback IP addresses for security reasons. While we can have hundreds of machines joining and leaving our cloud clusters, we could not guarantee what IP addresses our actual machines would be posting back from. So to address this, we have added a new “use_proxy” : true option which will send all postbacks through one of our proxy machines, thus ensuring that the IP addresses are always one of our listed IP addresses.
If you need to whitelist postback calls, you MUST have the following set on your Blitline JSON submissions:
The IP addresses which we proxy through are the following:
You must whitelist ALL 4 IP addresses.
When “use_proxy” : true is set, all postbacks will come through 1 of the IP addresses listed above.
You can see an example here: