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Sheep dip (computing) is a dedicated computer which is used to test files on removable media for viruses before they are allowed to be used with other computers. 〔(Webopedia definition of term "sheep dip" Retrieved on 11 April 2013. )〕 Such machines are a normal first line of defence against viruses in high-security computing environments〔Build Your Own Security Lab: A Field Guide for Network Testing (Page 269) ISBN 978-0470179864〕〔(forensic-computer-services.com ''Statement of Capability'' Retrieved on 11 April 2013. )〕 and IT security specialists are expected to be familiar with the concept.〔(Certified Ethical Hacker Course Overview (Lesson 9) Retrieved on 11 April 2013. )〕〔(EC-Council 312-49 Exam (Specimen question 2) Retrieved on 11 April 2013. )〕〔(ICAN Examination: Information Technology (Question 5) Retrieved on 11 April 2013. )〕 They were originally deployed in response to the problem of boot sector viruses on floppy discs. Subsequently their scope has been expanded to include USB flash drives, portable hard discs, memory cards, CD-ROMs and other removable devices, all of which can potentially carry malware. The name sheep dip is derived from a method of killing parasites in a flock of sheep by dipping all of the animals one after another in a trough of pesticide.〔 == Typical sheep dip system == A sheep dip is normally a stand-alone computer, not connected to any network. It has antivirus software in order to scan removable media and to protect the sheep dip computer itself. The system can be made more effective by having more than one antivirus program, because any single antivirus product will not be able to detect all types of virus.〔(AV-Comparatives ''independent tests of antivirus sortware'' )〕 It is very important to secure sheep dip computers as strongly as possible against malware, because their role as a first line of defence means that they are particularly likely to be attacked. Software updates should be applied as soon as they become available.〔(getsafeonline.org ''Software Updates'' Retrieved on 12 April 2013. )〕 Antivirus signatures should be the most up-to-date that are available,〔(getsafeonline.org ''Viruses & Spyware'' Retrieved on 12 April 2013. )〕〔(Symantec Corporation ''Virus Definitions and Security Updates'' Retrieved on 12 April 2013. )〕 which in practice means that they must be updated at least daily. The operating system should be hardened〔 (CPNI Good Practice Guide ''General Advice on Securing Operating Systems'' Retrieved on 27 May 2013. )〕 and locked down as far as possible. Network connections are avoided for two reasons. Firstly, an Internet connection is a potential attack vector via which the computer could be compromised. Secondly, there is a risk that a worm on a removable device might escape into a local area network if the sheep dip computer is connected to it. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sheep dip (computing)」の詳細全文を読む スポンサード リンク
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