Why Only One IP Per SSL?

**Sangeetha** · 27-Feb-2007, 08:05 PM

Question: Why is it that there can be only 1 SSL per IP Address? Is this because there are no host headers in SSL and thus, only one server can listen on that IP at port 443 at a time?

I assume if I change the IP address of the SSL - then in theory I could do hundreds of SSLs on one server? (this is hypothetical – I’m not actually looking to do this – but using it to better understand how SSL works.)

**Sangeetha** · 27-Feb-2007, 08:06 PM

You got it right. You can have multiple SSL certs for an IP Address, but only 1 SSL certificate per port on that IP Address. That is why only one cert can be associated with 443. A certificate authority such as VeriSign has to tie the certificate to something. The server's IP address is like it's phone number. When I use a certificate for Free Web Space and Site Hosting it resolves to the IP address. The server then decides which port to use with the certificate. The Certificate Authority doesn't care if you run the SSL cert on 443 or another port as long as it's on the right IP address.

This link has a lot of info on IIS and SSL.
http://www.microsoft.com/technet/pro...ty/c06iis.mspx

27-Feb-2007, 08:05 PM	#1 (permalink)
Sangeetha Fixed Error! Posts: 141 Location: Chennai Join Date: Feb 2007 Rep Power: 2 IM:	Why Only One IP Per SSL? Question: Why is it that there can be only 1 SSL per IP Address? Is this because there are no host headers in SSL and thus, only one server can listen on that IP at port 443 at a time? I assume if I change the IP address of the SSL - then in theory I could do hundreds of SSLs on one server? (this is hypothetical – I’m not actually looking to do this – but using it to better understand how SSL works.)

27-Feb-2007, 08:06 PM	#2 (permalink)
Sangeetha Fixed Error! Posts: 141 Location: Chennai Join Date: Feb 2007 Rep Power: 2 IM:	Re: Why Only One IP Per SSL? You got it right. You can have multiple SSL certs for an IP Address, but only 1 SSL certificate per port on that IP Address. That is why only one cert can be associated with 443. A certificate authority such as VeriSign has to tie the certificate to something. The server's IP address is like it's phone number. When I use a certificate for Free Web Space and Site Hosting it resolves to the IP address. The server then decides which port to use with the certificate. The Certificate Authority doesn't care if you run the SSL cert on 443 or another port as long as it's on the right IP address. This link has a lot of info on IIS and SSL. http://www.microsoft.com/technet/pro...ty/c06iis.mspx

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