Distributed Checksum Clearinghouse
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Distributed Checksum Clearinghouse
Distributed Checksum Clearinghouse (also referred to as DCC) is a method of spam email detection. The basic logic in DCC is that most spam mails are sent to many recipients. The same message body appearing many times is therefore bulk email. DCC identifies bulk email by calculating a fuzzy checksum on it and sending that to a DCC server. The server responds with the number of times it has received that checksum. An individual email will create a score of 1 each time it is processed. Bulk mail can be identified because the response number is high. The content is not examined. DCC works over the UDP protocol and uses little bandwidth. DCC is resistant to hashbusters because "the main DCC checksums are fuzzy and ignore aspects of messages. The fuzzy checksums are changed as spam evolves" DCC is likely to identify mailing lists as bulk email unless they are white listed. Likewise, repeatedly sending the same email to a server increases its number in the server, and, therefore, the like ...
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Spam (electronic)
Spamming is the use of messaging systems to send multiple unsolicited messages (spam) to large numbers of recipients for the purpose of commercial advertising, for the purpose of non-commercial proselytizing, for any prohibited purpose (especially the fraudulent purpose of phishing), or simply repeatedly sending the same message to the same user. While the most widely recognized form of spam is email spam, the term is applied to similar abuses in other media: instant messaging spam, Usenet newsgroup spam, Web search engine spam, spam in blogs, wiki spam, online classified ads spam, mobile phone messaging spam, Internet forum spam, junk fax transmissions, social spam, spam mobile apps, television advertising and file sharing spam. It is named after Spam, a luncheon meat, by way of a Monty Python sketch about a restaurant that has Spam in almost every dish in which Vikings annoyingly sing "Spam" repeatedly. Spamming remains economically viable because advertisers have no ...
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Fuzzy Checksum
A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify data integrity but are not relied upon to verify data authenticity. The procedure which generates this checksum is called a checksum function or checksum algorithm. Depending on its design goals, a good checksum algorithm usually outputs a significantly different value, even for small changes made to the input. This is especially true of cryptographic hash functions, which may be used to detect many data corruption errors and verify overall data integrity; if the computed checksum for the current data input matches the stored value of a previously computed checksum, there is a very high probability the data has not been accidentally altered or corrupted. Checksum functions are related to hash functions, fingerprints, randomization functio ...
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User Datagram Protocol
In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths. UDP uses a simple connectionless communication model with a minimum of protocol mechanisms. UDP provides checksums for data integrity, and port numbers for addressing different functions at the source and destination of the datagram. It has no handshaking dialogues, and thus exposes the user's program to any unreliability of the underlying network; there is no guarantee of delivery, ordering, or duplicate protection. If error-correction facilities are needed at the network interface level, an application may instead use Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP) which are designed for ...
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Bandwidth (computing)
In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which ''bandwidth'' is used to refer to analog signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel. Network capacity The term ''bandwidth'' sometimes defines the net bit rate 'peak bit rate', 'information rate,' or physical layer 'useful bit rate', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth ...
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Hashbusters
A hash buster is a program which randomly adds characters to data in order to change the data's hash sum. This is typically used to add words to spam e-mails, to bypass hash filters. As the e-mail's hash sum is different from the sum of e-mails previously defined as spam, the e-mail is not considered spam and therefore delivered as if it were a normal message. Hash busters can also be used to randomly add content to any kind of file until the hash sum becomes a certain sum. In e-mail context, this could be used to bypass a filter which only accepts e-mails with a certain sum. Initially spams containing "white noise" from hash busters tended to simply exhibit 'paragraphs' of literally random words, but increasingly these are now appearing somewhat grammatical. See also * Cryptographic hash function * Bayesian poisoning Bayesian poisoning is a technique used by e-mail spammers to attempt to degrade the effectiveness of spam filters that rely on Bayesian spam filtering. Bayesi ...
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Paul Vixie
Paul Vixie is an American computer scientist whose technical contributions include Domain Name System (DNS) protocol design and procedure, mechanisms to achieve operational robustness of DNS implementations, and significant contributions to open source software principles and methodology. He also created and launched the first successful commercial anti-spam service. He authored the standard UNIX system programs ''SENDS'', ''proxynet'', ''rtty'' and Vixie cron. At one point he ran his own consulting business, Vixie Enterprises. Career Vixie was a software engineer at Digital Equipment Corporation (DEC) from 1988 to 1993. After he left DEC in 1994, he founded Internet Software Consortium (ISC) in 1996 together with Rick Adams and Carl Malamud to support BIND and other software for the Internet. The activities of ISC were assumed by a new company, Internet Systems Consortium in 2004. Although ISC operates the F root name server, Vixie at one point joined the Open Root Server ...
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Vernon Schryver
Vernon may refer to: Places Australia *Vernon County, New South Wales Canada *Vernon, British Columbia, a city *Vernon, Ontario France * Vernon, Ard├Ęche *Vernon, Eure United States * Vernon, Alabama * Vernon, Arizona * Vernon, California * Lake Vernon, California * Vernon, Colorado * Vernon, Connecticut * Vernon, Delaware * Vernon, Florida, a city * Vernon Lake (Idaho) * Vernon, Illinois * Vernon, Indiana * Vernon, Kansas * Vernon Community, Hestand, Kentucky * Vernon Parish, Louisiana ** Vernon Lake, a man-made lake in the parish * Vernon, Michigan * Vernon Township, Isabella County, Michigan * Vernon Township, Shiawassee County, Michigan * Vernon, Jasper County, Mississippi * Vernon, Madison County, Mississippi * Vernon, Winston County, Mississippi * Vernon Township, New Jersey * Vernon (town), New York ** Vernon (village), New York * Vernon (Mount Olive, North Carolina), a historic plantation house * Vernon Township, Crawford County, Ohio * Vernon Township, Scioto ...
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