HOW TO: Determine If SSL Connectivity Is Not Working on the Web Server or on an Intermediate Device

This step-by-step article describes how to determine if Secure Sockets Layer (SSL) connectivity is not working on the Web server or on a intermediate device that is on the path from the client to the Web server.

After you install a Secure Sockets Layer (SSL) certificate on a computer that is running Internet Information Server (IIS) or Internet Information Services (IIS), you may find that you cannot connect to the computer across the Internet. When you try to connect, you may receive the following error messages in the browser: and

Determine the Cause of the Problem

One possible cause of this error is that an intermediate device, such as a router or a firewall, is blocking TCP port 443 requests to the server.

Make an SSL Request to the Server

To isolate this as a possible cause, first make sure that an SSL request to the server on the server is successful. After you install the SSL certificate, you can make an SSL request to the server by using the browser on the server (that is, connect to https://www.commonnameonthecertificate.com by using the browser on the Web server).

If this step is not successful, see the Troubleshooting section.

Find the Blocking Intermediate Device

If you can connect to the server, follow these steps to confirm that an intermediate device is blocking the SSL traffic:

1. On the Web server, open a command prompt and use the Microsoft TCP/IP Tracert utility to connect to a known Web server on the Internet that has an SSL certificate installed (such as www.microsoft.com). This shows all of the "hops" between the Web server and the destination server.
   
   The -d switch tells Tracert not to map IP addresses to host names.

   tracert www.microsoft.com -d
     1    20 ms    10 ms    10 ms  24.25.66.1
     2   <10 ms    10 ms    10 ms  24.93.65.149
     3   <10 ms    10 ms   <10 ms  24.93.66.145
     4   <10 ms    10 ms    10 ms  24.93.66.178
     5    20 ms    20 ms    20 ms  64.240.245.81
     6    20 ms    20 ms    20 ms  208.30.202.5
     7    20 ms    20 ms    20 ms  144.232.8.229
     8    40 ms    30 ms    30 ms  144.232.18.33
     9    40 ms    30 ms    40 ms  144.232.26.1
    10    40 ms    30 ms    30 ms  144.232.26.6
    11    80 ms    71 ms    70 ms  144.232.18.49
    12    70 ms    70 ms    70 ms  144.232.6.89
   					

2. When you have obtained this information, use the Microsoft TCP/IP Telnet utility to determine which router is blocking the SSL traffic. First, try to telnet to port 443 on the first hop that is reported from the Tracert output.
   
   For example, telnet to each hop that is listed in the Tracert output:

   telnet 24.93.65.149 443
   					

   When a connection is made to a listening SSL port, the telnet session shows a blank flashing cursor, as if the server is waiting for input. After several seconds, or if you press any keys, the telnet client displays the following:
   Connection to host lost.
   A connection to a server that is not listening on SSL immediately returns the following message:
   Could not open a connection to host on port 443 : Connect failed
3. Continue this process for each item on the Tracert list until you have determined the first intermediate device that is blocking SSL connections. After you find that device, work with the administrator of that device to correct this issue, and then try to connect to the site from the Internet.

Troubleshooting

For additional information about what to do if using the browser on the Web server is not successful, click the article numbers below to view the articles in the Microsoft Knowledge Base:

For additional information about using the Microsoft TCP/IP Tracert and Telnet utilities, click the article numbers below to view the articles in the Microsoft Knowledge Base: For additional information about SSL browsing failures on a Web server, click the article numbers below to view the articles in the Microsoft Knowledge Base: