Internet filtering

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Internet filtering

Blocking content coming into and going out to the Internet. Accomplished by firewall software residing in a stand-alone device, router or user's machine or in a filtering program in each user's machine, content can be blocked based on website address or Internet service. For example, users might be allowed access to the Web but not to transfer files (see FTP).

Websites and Internet Services
Incoming content can be blocked for specific users or for all users. Blocked websites can be recognized by their Web address (URL) or by elements within the URL. All Internet traffic is identified by port number, and an entire service can be blocked by this number. For example, websites use port 80 and file transfers are 20, 21 and 22 (see well-known port).

Outgoing requests to the Web can be compared with local and cloud-based databases of known malicious URLs. In addition, depending on company policy, lists of restricted website categories can be maintained such as shopping, news, streaming videos and pornography.

In the home, parents can restrict their children's access with special browsers and filtering programs (see parental control software).
References in periodicals archive ?
The content filter distributes the stream internally many times.
03's four new spam-blocking features: Identify adult subjects even if subject line is using an alternate character set or Base 64 encoding; automatically add a sender's IP address to the spam content category of the integrated content filter database if the majority of e-mail from that address is spam; conduct a DNS query on known spam URLs and add the corresponding IP addresses to the spam category in the content filter database; and check the IP addresses of unknown URLs to determine whether they are from a spam-categorized IP address.
Skip authenticated users--The receiving email server can allow all email from authenticated users (users that provided a username and password during the SMTP transaction) to bypass the content filters.
The SDK includes a range of site and content filters as well as productivity filters which can restrict access to non-work related sites in business applications.

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