Say I have a website, http://www.mostlysecuresite.com, which runs on a server at my house. Let's say I wanted to get an SSL cert in a few weeks. Because of this, I had my Port 443 forwarded on my router to my server, and the firewall was open for it. Could an attacker theoretically harm my server through this open port?

Just wondering.

  • 1
    Consider what will happen if someone tries to open a connection. They send a TCP SYN packet. Do some experiments with nmap to see what results you can get (connection success, OS fingerprinting, host enumeration etc.).
    – David
    Nov 27, 2018 at 23:11

1 Answer 1


When you open the ports to the public internet the security of your server relies on that of the application behind the corresponding port. So if you have an application running on 443 that is vulnerable to some sort of an attack then you will now have opened up a vulnerability to the internet. However; I'm assuming that if you are about to use that port for SSL you are confident there are no security vulnerabilities in the software running on that port.

To put it simply, opening that port before you have the SSL cert in place does not create any more vulnerabilities that what would be there when you did have the SSL cert besides the possibility of a MITM on a client using the web application.

  • True, but in this case I think nothing is running on port 443 yet. Nov 28, 2018 at 1:14
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    Then you're fine. Mapping an external port to an IP that won't respond to it offers no additional security concerns than blocking it from the router.
    – MikeSchem
    Nov 28, 2018 at 2:53

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