(solved) CFW 10 blocking Outlook, Firefox Sync

I’ve installed CFW on freshly installed Windows 10, and Outlook 2013 and latest Firefox are exhibiting connectivity problems. Specifically, Outlook can’t connect to outlook.com, and Firefox fails to synchronize data using its “Sync” feature (regular browsing works). Both of these problems are fixed if i disable the firewall.

My set of global rules is fairly standard - blocking all incoming connections that aren’t from localhost or LAN, allow all outgoing. enabling “block and log” doesn’t reveal any blocked activity, which leads me to believe the problem is somewhere in the application rules, however i can’t see anything wrong with them - i don’t have many “block” rules, and those that are engaged have nothing to do with either Firefox itself, or any Windows services (which might be suspect for Outlook).

I have only recently upgraded to both CFW 10 and Windows 10. Previous installation of Windows 7 and some older COMODO version (no idea which specific version, sorry) did not have such problems. Defense+, Antivirus, Viruscope, Sandboxing and Web filtering are disabled.

What may be relevant is that both Outlook and Firefox are running inside a Sandbox (using Sandboxie), but i’m pretty sure connectivity problems persisted even when running outside sandbox. I’ll double-check this when i get home.

The firewall is set to Custom Ruleset, so anything no explicitly allowed or denied will get asked, however the firewall was running in Training Mode for a while, so it automatically created rules for both Outlook and Firefox. To be safe, i removed them and made sure Firefox/Outlook asked for access, and they did - that didn’t help resolve the problems i’m having.

I’m pretty sure the culprit is a misconfigured application rule, but i’m not sure where else to look, since i’ve already checked all application rules and determined them to be OK as far as i can tell. In the meantime, i’d appreciate any pointers as to where else i could look for a solution and what else i could try.


I recently upgraded to cis 10 and outlook has stopped working for me.

I tried to check my emails in my outlook chrome tab and the internet essentials box popped up and i denied access (thinking it would block the adverts). This has now broken outlook for chrome and firefox, but not for explorer and dragon…

I don’t know how to reverse this rule, aside from reinstalling. alternatively it may have broken by itself, much like your problem, Burillo. Do you or anyone else know how to view/delete firewall/internet essential rules??

Disabling sandbox means i can log into outlook again (lol)

Actually, i figured out the solution :slight_smile:

It wasn’t sandboxing that’s for sure. There was nothing in the application rules, however, i’ve had “Windows Operating System” in “blocked” list for some reason. Unblocking it gave me both Outlook and Firefox Sync working again. Hope this helps someone else, and may that be a lesson to whoever implemented this functionality (hint: it would’ve been much easier if “blocked” applications also appeared in application rules!).

@silvercanary the blocks can be in three places: blocked applications (check the main CFW interface), application rules (Settings → Firewall → Application rules) or global rules (Settings → Firewall → Global rules), although the latter is rather unlikely.

alternatively, you may not have blocked the connection, but rather the application, in which case you would want to check your HIPS rules as well (i have it disabled so that wasn’t a problem for me).

my hips are also disabled…

And all my firewall rules are custom apart from the 2 that are outgoing only, Metro apps and cis.
I don’t see one specific windows operating system file, just a list of system files and some other stuff.

Aaaand my sandbox enabled itself once the disabled timer ran out, i can still access hotmail…???

i guess i fixed it also… ??? :-TU dfq