Securing windows networks and systems requires recognizing potential vulnerabilities and selecting the best control to address that vulnerability. as a security administrator working for ken 7 windows limited, you have been instructed to ensure that windows authentication, networking, and data access are hardened. this will to provide a high level of security. you can select from a short list of security controls. for each security policy statement listed below, select an appropriate hardening technique to meet the requirements of the security policy statement. provide rationale for each selection. select from these hardening techniques: place a firewall between the internet and your web server. place a firewall between your web server and your internal network. enforce password complexity. implement kerberos authentication for all internal servers. run weekly update checks for all software to ensure the latest patches have been applied. create a set of new user accounts with administrator privileges and disable all administrative-level user accounts. require all personnel attend a lunch and learn session on updated network security policies. security policy statements: previous attempts to protect user accounts have resulted in users writing long passwords down and placing them near their workstations. users should not write down passwords or create passwords that attackers could easily guess. every user, regardless of role, must have at least one unique user account. a user who operates in multiple roles may have multiple unique user accounts. users should use the account for its intended role only. anonymous users of the ken 7 web application should only be able to access servers located in the demilitarized zone (dmz). no anonymous web application users should be able to access any protected resources in the ken 7 infrastructure. to protect servers from attack, each server should authenticate connections based on the source computer and user. passwords should not be words found in the dictionary.

Infrared sensor is most used sensor in wireless technology where remote controlling functions and detection of surrounding objects/ obstacles are involved. this post will discuss about what is infrared sensor, its working principle, how it works, types, applications, advantages and disadvantages. what is infrared sensor

ir sensor is a simple electronic device which emits and detects ir radiation in order to find out certain objects/obstacles in its range. some of its features are heat and motion sensing.

ir sensors use infrared radiation of wavelength between 0.75 to 1000µm which falls between visible and microwave regions of electromagnetic spectrum. ir region is not visible to human eyes. infrared spectrum is categorized into three regions based on its wavelength i.e. near infrared, mid infrared, far infrared.

wavelength regions of infrared spectrum

near ir – 0.75µm to 3 µm
mid ir – 3 µm to 6 µm
far ir – > 6 µm
1 introduction to infrared sensor

fig. 1 – introduction to infrared sensor

working principle of infrared sensor

infrared sensors works on three fundamental physics laws:

planck’s radiation law: any object whose temperature is not equal to absolute zero (0 kelvin) emits radiation.
stephan boltzmann law: the total energy emitted at all wavelengths by a black body is related to the absolute temperature.
wein’s displacement law: objects of different temperature emit spectra that peak at different wavelengths that is inversely proportional to temperature.
key elements of infrared detection system

the key elements of infrared detection system are:

ir transmitter

ir transmitter acts as source for ir radiation. according to plank’s radiation law, every object is a source of ir radiation at temp t above 0 kelvin. in most cases black body radiators, tungsten lamps, silicon carbide, infrared lasers, leds of infrared wavelength are used as sources.

transmission medium

as the name suggests, transmission medium provides passage for the radiation to reach from ir transmitter to ir receiver. vacuum, atmosphere and optical fibers are used as medium.

ir receiver

generally ir receivers are photo diode and photo transistors. they are capable of detecting infrared radiation. hence ir receiver is also called as ir detector. variety of receivers are available based on wavelength, voltage and package.

ir transmitter and receivers are selected with matching parameters. some of deciding specifications of receivers are photosensitivity or responsivity, noise equivalent power and detectivity.