2020-05-04
A fault in my firewall 5 months ago
I have a Synology NAS at home running DSM, so I had a look at the certificate options. According to the documentation it can get a LetsEncrypt certificate so I tried that. And it worked... which wasn't what I expected. Some testing later found out port 80 tcp was open for every IPv6 address at home. That's now fixed and limited to those few IPv6 addresses that need to be reachable from the outside world. Browsing the opinions about allowing outside access to the webserver on the Synology versus not allowing it showed me some differing opinions, but an article listening some malware and ransomware targetting Synology systems made me decide to close the system. Looking at the nginx configuration on the Synology gives me the idea some of the web-accessible functionality is available via port 80.