Public Information Sources

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A certain amount of information is required for an organization to successfully participate on the Internet. This includes name services, which resolves names into physical addresses for public sites, enough information to successfully exchange e-mail and a web presence. These servers and services need to provide information without leaking unnecessary information which can be used to compromise the organization's information infrastructure.

Domain Name Service

Domain name service is a hierarchical organization of names used to identify systems on the Internet. Name services provide the correlation between a system's name and its address. Every system which requires public access from the Internet needs a unique name and address. However, systems which do not need to be accessed from users on the Internet do not need to have their addresses published to the public.

Split DNS is a method of dividing the name resolution between access from the internal network and those from an external network. In this manner, the external users see only those systems which are exposed to the Internet, while the internal users can resolve the names of all the intranet systems. Historically, this was accomplished by dividing public and private names by separating them onto different servers for inside and outside as mentioned in RFC 1918. Resolvers would receive different answers depending on whether they were on the inside or outside. BIND v9 implements another method (based on the IETF draft) to achieve the effect of local names that is more in tune with the concept of a single global DNS tree or at least the appearance of a single tree. Use of this approach is not required, and older techniques will continue to work.

Webservers

Webservers provide an organization with its presence on the Internet. They supply people with information about the company and facilitate e-business by providing shopping, ordering, and order tracking. The level of visibility of these servers have made them popular targets of hackers. Web servers often provide more information than what is needed. Enthusiastic web designers may publish unnecessary information, such as the type of systems and the tools used in the creation and support of the websites. Information placed on public websites should be limited to the business details needed for the site and should be evaluated before being made public.

Web development tools will often insert documentation into the code which they produce. These comments often identify the tool and the version of the software used to produce the web page. They may also include information about to whom the tool is registered, and the systems which were used to create the document. The output of these design tools should be examined to determine what information they are disclosing and this output should be stripped of all unnecessary information.

The web server software may also expose information about the vendor and version of software and hardware powering the website.

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