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Preventing Denial of Service Attacks

Denial of service (DoS) attacks can take different forms. However, the most common method involves one or more computers (often hijacked personal computers) bombarding a Web site or Web-accessible service with a large number of simultaneous requests. The affected servers are overwhelmed and the connections and processes are prevented from running. These types of attacks are almost always targeted against public-facing Web sites and applications.

The following steps can help prevent DoS attacks from affecting your employee-facing Siebel Business Applications:

• Use different Web servers for public-facing applications and for employee-facing applications so that even if the public Web servers are overwhelmed, Web servers are still available to service employee applications. For additional information, see Proxy Servers.
• Run the employee-facing Application Object Managers and key components on different Siebel servers from those used to run public-facing Application Object Managers. This step helps to make sure that even if the Siebel Servers that process external applications are overwhelmed with requests, hardware resources are available to continue processing internal applications. For additional information, see Load Balancers.

Other methods available when configuring firewalls to assist in preventing DoS attacks include designing them to reject rapid requests from the same IP address, or to blacklist specific IP addresses or domains. These methods are not foolproof and it might not be possible to use blacklisting on large public sites. For example, many DoS attacks use hijacked computers that are on large, well-known, Internet service providers. Blacklisting all of the users in these domains or IP ranges helps prevent the DoS attacks, but possibly prevents many valid users from using your Web site as well.