Facebook deauthorization callback is not called

Question

I have an FB app, when I enter as the deauthorization callback URL my development box address, the box is pinged with this request after app removal on FB:

POST /facebook/deauthorize HTTP/1.1
Host: bashman.org
Accept: */*
Content-Length: 261
Content-Type: application/x-www-form-urlencoded
Connection: close

fb_sig_uninstall=1&fb_sig_locale=de_DE&fb_sig_in_new_facebook=1&fb_sig_time=1322732591.2685&fb_sig_added=0&fb_sig_user=1476224117&fb_sig_country=de&fb_sig_api_key=e39a74891fd234bb2575bab75e8f&fb_sig_app_id=32352348363&fb_sig=f6bbb27324aedf337e5f0059c4971

(The keys are fake here)

BUT! when I enter my production box URL in the deauthorization callback URL, the POST request is never made. Tested it with Tcpdump. No request on my production machine, why?

I checked with mtr the route from my production box to the IP address the request came from, all is OK, 0% packet lost.

The hostname port and path is correct, tested it 1k times, no firewall, IDS, or other systems blocking my ethernet slot.

1. Why is the Post callback not called? (How can I fix it?)

2. How I can debug this to determine what the issue is?

Answer 1

You can try using the facebook URL Debugger and see if facebook's servers are able to reach your callback URL...
Viewing the information facebook IS able to retrieve might help you debug this issue.