Monday, May 21, 2012

Network Connectivity Status Indicator

Windows Server 2008 includes a feature called Network Connectivity Status Indicator (NCSI), which is part of a broader feature called Network Awareness. Network Awareness collects network connectivity information and makes it available through an application programming interface (API) to services and applications on a computer running Windows Server 2008. With this information, services and applications can filter networks (based on attributes and signatures) and choose the networks best suited to their tasks. Network Awareness notifies services and applications of changes in the network environment, thus enabling applications to dynamically update network connections.
Network Awareness collects network connectivity information such as the Domain Name System (DNS) suffix of the computer and the forest name and gateway address of networks that the computer connects to. When called on by Network Awareness, NCSI can add information about the following capabilities for a given network:
  • Connectivity to an intranet
  • Connectivity to the Internet (possibly including the ability to send a DNS query and obtain the correct resolution of a DNS name)
NCSI is designed to be responsive to network conditions, so it examines the connectivity of a network in a variety of ways. For example, NCSI tests connectivity by trying to connect to http://www.msftncsi.com, a simple Web site that exists only to support the functionality of NCSI.

Overview: Using NCSI in a Managed Environment

In a managed environment, you might choose to use NCSI because of the way it supports services and applications that require network connectivity. However, you can disable NCSI through Group Policy.

How NCSI Communicates with a Site on the Internet

The following list describes how NCSI might communicate with a Web site to determine whether a network has Internet connectivity:
Specific information sent or received:

  • Type of Request that NCSI Sends What NCSI Expects to Receive if Connectivity Exists
    A request for http://www.msftncsi.com/ncsi.txtA page called ncsi.txt containing the following line of text with no terminating new line or other non-printing characters:
    Microsoft NCSI
    (Page headers disable caching.)
    A request for DNS name resolution of dns.msftncsi.comThe resolution of the DNS name to:
    131.107.255.255
  • Default setting and ability to disable: By default, Network Awareness (which includes NCSI) is enabled. NCSI can be disabled by using Group Policy.
  • Triggers: Network Awareness and its subfeatures gather information flexibly—that is, by using complex algorithms that respond to changing network conditions. This means that triggers can vary, but the following are examples of typical triggers that can cause NCSI to communicate across the Internet:

    • Someone first logs on after the computer has been restarted
    • The computer connects to a different network
    • The computer is brought into a hot spot (public wireless access area) that requires sign-in
  • User notification: NCSI does not notify the user before attempting to collect information. It does notify the user or the application when there are changes in connectivity (for example, loss of Internet connectivity). Note that an application that uses NCSI can be written to include user notifications if appropriate to the design and function of the application.
  • Logging: NCSI does not log events in Event Viewer.
  • Privacy, encryption and storage: NCSI does not use encryption (both the requests it sends and the responses it receives are standardized, as shown in the table earlier in this subsection). Internet Information System (IIS) logs are stored on the server at www.msftncsi.com. These logs contain the time of each access and the IP address recorded for that access. These IP addresses are not used to identify users, and in many cases, they are the address of a network address translation (NAT) computer or proxy server, not a specific client behind that NAT computer or proxy server.
  • Transmission protocol and port: NCSI uses HTTP over port 80. For DNS requests, NCSI uses the DNS port, which by default is port 53.

Controlling Communication Between NCSI and a Site on the Internet

You can prevent NCSI from connecting to http://www.msftncsi.com by using Group Policy. The following subsections provide more information.

How Preventing NCSI from Communicating Across the Internet Can Affect Users and Applications

If you use Group Policy to prevent NCSI from connecting to http://www.msftncsi.com, applications that perform checks for the existence of Internet connectivity might work more slowly. Also, if a computer running Windows Server 2008 is brought into a hot spot that requires sign-in, the computer might not detect the hot spot.

Procedures for Controlling Communication Between NCSI and a Site on the Internet

The following procedure describes how to use Group Policy to prevent NCSI from communicating across the Internet.

To Prevent NCSI from Communicating Across the Internet by Using Group Policy

  1. See Appendix B: Resources for Learning About Group Policy for Windows Server 2008 for information about using Group Policy. Using an account with domain administrative credentials, log on to a computer running Windows Server 2008 (with the Group Policy Management feature installed) or running Windows Vista with SP1 and containing the Group Policy Management Console (GPMC) that is included in Remote Server Administration Tools for Windows Server 2008. Open GPMC by running gpmc.msc, and then edit an appropriate Group Policy object (GPO).
    You must perform this procedure on a computer running the software described in this step.
  2. Expand Computer Configuration, expand Policies, expand Administrative Templates, expand System, expand Internet Communication Management, and then click Internet Communication settings.
  3. In the details pane, double-click Turn off Windows Network Connectivity Status Indicator active tests, and then click Enabled.

    You can also restrict Internet access for this and a number of other features by applying the Restrict Internet communication policy setting. This setting is located in either Computer Configuration or User Configuration, in Policies\Administrative Templates\System\Internet Communication Management. For more information about this Group Policy and the policies that it controls, see Appendix C: Group Policy Settings Listed Under the Internet Communication Management Category in Windows Server 2008.

Additional References

For more information about how applications can use Network Awareness in Windows Server 2008, see the MSDN Web site at:
http://go.microsoft.com/fwlink/?LinkId=108692

65 comments:

Anonymous said...

xanax for sale without prescription xanax bars green monsters - xanax for anxiety during pregnancy

Anonymous said...

buy tramadol online signs of tramadol addiction - tramadol hcl 50 mg high

Anonymous said...

generic xanax mask xanax drug test - generic brand name xanax

Anonymous said...

generic xanax xanax overdose management - xanax buy online no prescription uk

Anonymous said...

xanax online buy xanax online no membership - xanax drug code

Anonymous said...

carisoprodol 350 mg carisoprodol 350 mg efectos secundarios - carisoprodol 350 mg maximum dosage

Anonymous said...

generic xanax buy xanax online in canada - xanax xr duration

Anonymous said...

buy tramadol online buy generic tramadol no prescription - tramadol overdose what to do

Anonymous said...

buy xanax bars online xanax and alcohol recreational - xanax bars while pregnant

Anonymous said...

buy xanax online forum buy xanax online yahoo answers - xanax 7 weeks pregnant

Anonymous said...

order tramadol tramadol hcl time release - will 50mg tramadol do you

Anonymous said...

where to buy tramadol online tramadol withdrawal paws - buy tramadol overnight no prescription

Anonymous said...

xanax online buy xanax online prescription - xanax drug maker

Anonymous said...

carisoprodol 350 mg carisoprodol side effects long term - carisoprodol generic

Anonymous said...

buy tramadol online buy tramadol online no prescription cheap - tramadol 100mg retard

Anonymous said...

buy carisoprodol carisoprodol 350 mg street name - carisoprodol 350 mg

Anonymous said...

generic xanax 8mg xanax overdose - xanax you buy online real

Anonymous said...

buy tramadol online tramadol 50 mg tab amneal - tramadol 100

Anonymous said...

buy tramadol online order tramadol cheap - tramadol 20mg dogs

Anonymous said...

buy tramadol online tramadol ultram high - tramadol medication addiction

Anonymous said...

buy carisoprodol carisoprodol dosage for back pain - does carisoprodol 350 mg have codeine

Anonymous said...

buy tramadol online order tramadol online safely - does generic tramadol look like

Anonymous said...

buy tramadol online tramadol buy australia - buy tramadol online no prescription cheap

Anonymous said...

buy cialis generic cialis online free trial - cialiscoupon

Anonymous said...

cialis no prescription overnight cialis daily safe - cialis 40 mg reviews

Anonymous said...

buy cialis online buy generic cialis online - generic cialis reviews

Anonymous said...

buy cialis 10mg cialis online mexico - cheap cialis for sale

Anonymous said...

cialis online buy cialis generic us - cialis daily for sale

Anonymous said...

xanax online xanax online pharmacy - how to buy xanax online

Anonymous said...

cialis online buy cialis online pay with paypal - get real cialis online

Anonymous said...

http://buytramadolonlinecool.com/#30694 100mg tramadol lot - tramadol hcl bp

Anonymous said...

buy tramadol tramadol 50 mg in dogs - tramadol dosage 150 mg

Anonymous said...

http://landvoicelearning.com/#23561 tramadol with acetaminophen dosage - discount tramadol online

Anonymous said...

buy tramadol tramadol hcl 50 mg tablet side effects - buy tramadol online forum

Anonymous said...

buy tramadol for dogs tramadol no prescription overseas - tramadol overdose in dogs

Anonymous said...

buy tramadol tramadol addiction forum 2012 - tramadol vs percocet

Anonymous said...

tramadol online tramadol veterinary dosage chart - tramadol for dogs sleepy

Anonymous said...

learn how to buy tramdadol buy tramadol online echeck - tramadol-ct 100mg retardkapseln beipackzettel

Anonymous said...

tramadol 100 tramadol order online no prescription - tramadol for dogs safe

Anonymous said...

buy tramadol day 2 tramadol withdrawal - buy tramadol online cheap

Anonymous said...

http://landvoicelearning.com/#23561 tramadol hcl 50 mg picture - next day tramadol review

Anonymous said...

buy tramadol can you buy tramadol over counter - tramadol hcl zoloft

Anonymous said...

http://buytramadolonlinecool.com/#56411 tramadol no prescription mastercard - buy tramadol usa pharmacy

Anonymous said...

buy tramadol is tramadol online real - buy cheap tramadol overnight

Anonymous said...

http://buytramadolonlinecool.com/#59473 tramadol 50 mg and breastfeeding - tramadol long before addiction

Anonymous said...

buy tramadol cheap online tramadol 50 mg ratiopharm - buy tramadol online with american express

Anonymous said...

tramadol online buy tramadol online cash delivery - how to buy tramadol online

Anonymous said...

tramadol online no prescription tramadol nice high - many tramadol 50mg get high

Anonymous said...

ativan anxiety ativan withdrawal tingling - ativan withdrawal timeline

Anonymous said...

ways to buy ativan online buy lorazepam online no prescription - ativan side effects constipation

Anonymous said...

http://reidmoody.com/#54126 dosage of ativan for sleep - ativan drug addiction

Anonymous said...

http://ranchodelastortugas.com/#71453 order upjohn xanax - xanax overdose with alcohol

Anonymous said...

buy tramadol online tramadol overnight no prescription - tramadol 50 mg kapseln dosierung

Anonymous said...

http://ranchodelastortugas.com/#71453 xanax dosage valium - xanax overdose how many pills

Anonymous said...

buy tramadol online buy tramadol cod free - buy tramadol online safely

Anonymous said...

http://staam.org/#21236 tramadol overnight delivery to florida - tramadol online with cod

Anonymous said...

buy xanax online xanax side effects dizziness - generic name for xanax

Anonymous said...

buy xanax online xanax side effects anxiety - xanax dosage one time

Anonymous said...

Υour сurrent article ρrovides establisheԁ beneficial to me ρersonally.
Ιt’ѕ quіte uѕеful аnԁ you
аre obviouѕly extгеmely wеll-informed in thіs
field. Yοu havе opened my sight to be аble
to differеnt оpiniοn of this subject usіng interesting and sounԁ articles.
my website > buy viagra online

Anonymous said...

Τhe ωritе-up haѕ ѵerified useful to mе
рeгsonally. It’s extrеmely helpful and you're simply obviously quite knowledgeable of this type. You have got exposed our eye for you to different thoughts about this specific matter along with interesting and reliable content material.
Also visit my webpage ; viagra

Anonymous said...

Yοur article hаs confігmed nеcеssaгу to
me. It’s really useful аnԁ you're simply obviously really knowledgeable in this field. You have opened my personal eyes in order to numerous opinion of this specific topic with interesting and reliable articles.
my site > Going In this article

Anonymous said...

The write-up offerѕ proven beneficial to me.

It’s quite educational and you're simply obviously extremely well-informed in this region. You get popped my eye to be able to different views on this specific matter with intriguing and solid written content.
Have a look at my blog post ... Buy Valium

Anonymous said...



Also visit my page website

Anonymous said...



Have a look at my web page ... web site

Anonymous said...

Your own ρost offers confirmed useful tο me.

It’s quite useful аnd you аre natuгally eхtгemеly well-infoгmeԁ in this regіon.
You get expоsed mу own face tο numerous thoughtѕ about thiѕ kіnd of subϳect matter together with іntriguing, notаble anԁ sound written
сontеnt.
Here is my blog post :: http://www.waagg.com

Quote of the Day