Help with vulnerability scan results

Nessus result: SSL Issues - medium strength cipher suites - The remote host supports the use of SSL ciphers that offer medium strength encryption. Nessus regards medium strength as any encryption that uses key lengths at least 64 bits and less than 112 bits, or else that uses the 3DES encryption suite.

Port: 443/tcp/www Hosts - x.x.x.x (public IP)

The scan was run externally, so my thought is just the firewall settings or whatever is open to the public on that specific port.

Here are the NMAP results as well from an external scan to my public IP:

PORT STATE SERVICE

25/tcp filtered smtp

70/tcp open gopher

80/tcp open http

135/tcp filtered msrpc

136/tcp filtered profile

137/tcp filtered netbios-ns

138/tcp filtered netbios-dgm

139/tcp filtered netbios-ssn

443/tcp open https

445/tcp filtered microsoft-ds

I understand cryptography and exactly what they're talking about when it comes to the vulnerability. However, how do I track down exactly what has these settings enabled? That is the part I just can't wrap my head around. 443 is SSL and I have a lot of services that would use SSL - RDGateway, SSL VPN on firewall, IIS Web Server, regular HTTPS traffic from a web browser.

Any explanation would be great!