@NogBadTheBad:
Thats HTTP inspection doing that.
View the following page on your pfSense router :-
Services -> Snort -> Alerts and select the WAN interface and write down the SID number, you get more details about the alert here.
Then goto :-
Services -> Snort -> Edit Interface -> WAN -> WAN Rules and select pulldown preprocessor.rules.
You can serach for the SID there.
BTW I see these all the time :-
09:03:42 2 TCP Potentially Bad Traffic 172.16.2.41 52863 17.120.225.104 993 137:1 (spp_ssl) Invalid Client HELLO after Server HELLO Detected
IMO you'd be better running SNORT on the LAN interface rather than the WAN interface as you'll see the client IP address rather than the WAN IP address.
It also looks like you've got a double NAT going on as your WAN IP address is in RFC1918 address space.
Thank you Nogbadthebad for responding with good insight. I plan to move soon; so, in the mean time, I am using my neighbor's WIFI, with permission of course, via a WIFI repeater that has an Ethernet port.
My setup is PFSense for WAN and Mikrotik for LAN…so, even when I move; that's my official home network. So, Snort will always on WAN...in fact, that's exactly I got pfSense machine because although the Mikrotik is robust, I wanted to use pfSense to complement it to bring about, hopefully, the ultimate UTM.
That's why I might have double NAT although only the Mikrotik has NAT enabled. I checked the SID...it's the same 137:1.