how to implement barcode system in c# Lesson 3 in C#

Print Quick Response Code in C# Lesson 3

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For more information about how to request and install a certificate from a commercial CA, see the Knowledge Base article, Generating a Certificate Request File Using the Certificate Wizard in IIS 5.0, located at http://support.microsoft.com/kb/228821/EN-US and the Knowledge Base article named Installing a New Certificate with Certificate Wizard for Use in SSL/TLS, located at http://support.microsoft.com/kb/228836/EN-US.

When you request the certificate, the name on the certificate must be the FQDN that users use to access the Web site. For example, if you are deploying the certificate on an ISA Server computer named ISA1.cohovineyard.com, but users will be using an FQDN of secure.cohovineyard.com to connect to the server, the certificate name must be secure.cohovineyard.com. If the common name on the certificate does not match the FQDN used by client computers to access the Web site, clients will receive an error message when they send HTTPS requests. If you plan to use SSL tunneling or if you plan to configure a secure connection between the ISA Server computer and the Web server, you will need to request and install a server certificate on the Web servers. The name on the certificate must be the FQDN that ISA Server uses to access the Web site. For example, if the Web publishing rule specifies Web1.cohovineyard.com as the internal server name, then this must be the FQDN on the certificate. This must also be the FQDN used by clients to connect to the server in an SSL tunneling scenario. You must install this certificate before the Web servers can accept SSL tunneling connections and before the Web servers can accept secure connections from ISA Server.

One of the options that ISA Server provides for securing network traffic is SSL bridging. SSL bridging means that the ISA Server computer operates as the end point for an SSL connection. The SSL connection could be between ISA Server and the client or between ISA Server and the internal Web server. The primary benefit of using SSL bridging is that it enables application filtering of SSL traffic.

SSL bridging is used when ISA Server ends or initiates an SSL connection. This connection can be with the client computer, with the internal Web server, or both. A common scenario in which SSL bridging is used is in a Web publishing scenario. The scenario works as follows: 1. An external client uses HTTPS to request an object from a Web server located on the internal network. By default, the client connects to ISA Server on the standard SSL port, Port 443. ISA Server responds with a server-side SSL certificate to the client and the client authenticates the server. After authentication, the client and server create a secure encryption channel.

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2. ISA Server accepts the client s request and decrypts it, terminating the SSL connection. ISA Server inspects the client request to ensure that the request is not blocked by a firewall access rule. If the request is not blocked, ISA Server continues processing the request. If ISA Server is configured to enable caching, and the object is in the cache, ISA Server returns the object to the client. 3. If the object is not in the cache, ISA Server forwards the request to the internal Web server specified in the Web publishing rule. The Web publishing rule also defines how ISA Server communicates the request to the published Web server (FTP, HTTP, or SSL). If the secure Web publishing rule is configured to forward the request using HTTPS, ISA Server initiates a new SSL connection with the Web server, sending a request to Port 443. Because the ISA Server computer is now an SSL client, the Web server responds with a server-side certificate. 4. After the SSL connection has been created, the Web server responds by sending the requested object back to ISA Server. 5. ISA Server receives the object and decrypts it. At this point, ISA Server inspects the information based on the firewall access rules and the HTTP policy. If the reply is acceptable, ISA Server then encrypts the object again and passes it to the requesting client. One of the important benefits of using SSL bridging is that it allows stateful inspection of SSL connections and application-layer filtering of the contents of HTTPS packets. Because ISA Server decrypts each packet, it can inspect the application-layer data before re-encrypting the packet. This prevents attackers from hiding malicious code inside SSL packets. The most significant disadvantage with using SSL bridging is that encrypting and decrypting network traffic is CPU-intensive, so the ISA Server computer performance may be affected.