App Outgoing Internet Connections are Blocked

I am trying to activate an application which sends my serial number to a server. The send is being blocked.

This is actually the place I'd start, as the term "blocked" is extremely vague. There are a huge range failure points for any network connection, most of which look exactly the same ("the connection failed"). The first step to this kind of investigation is figuring out exactly what happened, as that generally tells you what the solution is. The details of how to perform that kind of investigation can't be easily summarized, but here are some articles the might help:

• Choosing a Network Debugging Tool

• Analyzing HTTP traffic with Instruments

• Taking Advantage of Third-Party Network Debugging Tools

Under what circumstances will Mac OS block outgoing internet connections from a non-sandboxed app?

In terms of what's part of the built in system, I can't think of any other cases beyond the one you listed. If the system did block something, it would have noted that in the system log (so you can check there) but my first guess would be that something else went wrong.

How else could the outgoing connection be blocked?

Again, this all depends on how closely you've investigated the failure and exactly what "failed". Strictly speaking, anything between your computer and the computer at the the other side of the connection can block the connection, however, the common failure points here are:

• The local router blocking or otherwise interfering with the connection.

• Issues with network "data" like DNS records preventing success.

__
Kevin Elliott
DTS Engineer, CoreOS/Hardware

How else could the outgoing connection be blocked?

There are four common causes of outgoing connections being blocked:

• App Sandbox

• The built-in firewall

• Third-party firewalls

• Local network privacy, as explained in TN3179.

• Actual networking problems

So, let’s start with some basics:

• What API are you using to make this connection?

• What error do you get?

• If the connection is HTTP, does curl work?

• If the connection is TCP, does nc work?

• Is this a local server?

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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Thank you very much for your responses.

The app I am trying to activate is sending a message to the developer's server. The developer sent me the URL and I am able to see it using Safari.

When I try to activate (by clicking on a link in the app), the app displays the error in a dialog: "An error occured while accessing the registration server. Your computer must be connected to the Internet. Also make sure your firewall or virusscanner is not blocking access to the Internet!"

The developer thinks this is a network issue on my end because the registration server is up and no other users have this problem. He thinks my machine is blocking outgoing network connections from his app. I don't know what protocol he is using to communicate.

Quinn, addressing your four common causes:

• The app is not sandboxed
• My MacOS firewall is turned off
• I don't have any third party firewalls that I know of
• The app doesn't appear under local network privacy

I use SpamSieve for email spam. That shouldn't be relevant here. I don't have any third party virus software currently. I have had such software in the past.

Update. I used Activity Monitor with the app selected. When I push the verify activation server button, I see 1 KB sent and 11 KB received, 8 packets sent, 10 packets received. So there is some communication with the server.

Also, this may have something to do with php. Two other features of the app that use php are failing.

I purchased IPNetMonitorX. It hung 3 times after installation but finally started to run. I tried using Connection List and ServerScan to no avail. What should I look for?