question: How can websites tell when you are using an Ad Blocker?
comment: There are a few methods, one of the easiest ways is to have your advertention server serve a piece of Javascript and then check if it loaded. URL_0 uses this Method
passages: The second principal approach used does not require page tagging. By establishing a DNS-proxy or hosting within a website's own datacenter, it is possible to intercept and process all web traffic to and from the site undergoing testing, insert variants and monitor visitor response. In this case, all logic sits on the server rather than browser-side, and after initial DNS changes are made, no further technical involvement is required from the website point of view. SiteSpect is known to employ this method of implementation.
  
  Multivariate testing can also be applied to email body content and mobile web pages.
   It has been suggested that in the European Union, the practice of websites scanning for ad blocking software may run afoul of the E-Privacy Directive. This claim was further validated by IAB Europe's guidelines released in June 2016 stating that there indeed may be a legal issue in ad blocker detection. While some anti-blocking stakeholders have tried to refute this it seems safe to assume that Publishers should follow the guidelines provided by the main Publisher lobby IAB. The joint effort announced by IAB Sweden prior to IAB Europe's guideline on the matter never materialized, and would have most likely been found against European anti-competition laws if it did.
   These methods do not detect the presence of the Adblock Plus extension directly, only the effects of the filters. They are vulnerable to continued filter updates, and whitelist-filtering web scripts with extensions such as NoScript.
  
  An attempt was made to detect the plug-in itself, but that detection method was rendered unusable by the 0.7.5.2 update of Adblock Plus.
   In other words, Drawbridge observes a user's activities, primarily through the proxy of ads served to various devices (mobile device or desktop web), which gives them an ID. Since IDs are different across all the devices a user may interact with, Drawbridge then computes a confidence-score based on the likelihood that IDs from different sources belong to the same person or identity.
  
  Section::::Reception.
   This data can sometimes be sent to more than 100 websites, and shared with business partners, advertisers, and other third parties for business purposes. The data is collected using cookies, web beacons and similar technologies, and/or a third-party ad serving software, to automatically collect information about site users and site activity. Some servers even record the page that referred you to them, websites you visit after them, which ads you see and which ads you click on.
   Some webmasters have used JavaScript to detect the effects of the popular Adblock Plus filters. This is done by generating a honeypot-like URL, verifying its delivery, and DOM verification after the web page is rendered by the web browser, to ensure the expected advertising elements are present. Detection is simplified since the extension is not yet capable of replacing content; Loopback proxies provide this additional functionality.
   Many websites rely on ads as a source of revenue, but the use of ad blockers is increasingly common. Websites that detect an adblocker in use often ask for it to be disabled - or their site to be "added to the whitelist" - a standard feature of most adblockers.
  
  Section::::LAN whitelists.
   Like Mozilla's built-in image blocker, Adblock Plus blocks HTTP and HTTPS requests according to their source address and additional context information and can block iframes, scripts, and Flash. It also uses automatically generated user stylesheets to hide elements such as text ads on a page as they load instead of blocking them, known as element hiding.
  
  Section::::Operation.:Android.
   Viewable Impression relies on Web bugs (or 'tags') placed on the web pages or in the third-party ad servers that distribute ads on the website(s) content pages. These tags are placed on a web page and when rendered, employing a "Correlator" (a linear correlation control.) The ad space is then "marked up," an "ad request” (server log impression) is recorded, and the Correlator begins communicating with the web page, browser and ad unit (ad space) embedded in the webpage content. The Correlator can collect additional non-private information from the viewer’s browser, including the viewer’s operating system, browser type and version and a list of other ads that were previously rendered on the page to prevent duplication of ads on the content page. Once any portion of the ad unit (definable), on a viewer's in focus web page, hits the visible area of the browser window a request is sent to an ad content server to deliver an advertisement.
   The web analytics service also manages the process of assigning a cookie to the user, which can uniquely identify them during their visit and in subsequent visits. Cookie acceptance rates vary significantly between websites and may affect the quality of data collected and reported.
  
  Collecting website data using a third-party data collection server (or even an in-house data collection server) requires an additional DNS lookup by the user's computer to determine the IP address of the collection server. On occasion, delays in completing a successful or failed DNS lookups may result in data not being collected.
   Monitoring options vary by service or product and range from monitoring a single web page at a time to entire web sites. What is actually monitored also varies by service or product with the possibilities of monitoring text, links, documents, scripts, images or screen shots.
  
  With the notable exception of Google's patent filings related to Google Alerts, intellectual property activity by change detection and notification vendors is minimal. No one vendor has successfully leveraged exclusive rights to change detection and notification technology through patents or other legal means. This has resulted in significant functional overlap between products and services.
   For a higher level of confidence, some feature tests will attempt to invoke the feature then look for clues that it behaved properly. For example, a test for support for cookies might attempt to set a value as a cookie and then verify it can be read back.
  
  Section::::Undetectables.
   Section::::Methods.:Recursive Local VPN.
  
  On Android, apps can run a local VPN connection with its own host filtering ability and DNS address without requiring root access. This approach allows adblocking app to download adblocking host files and use them to filter out ad networks throughout the device. Blokada, DNS66, AdGuard are few of the popular apps which accomplish adblocking without root permission. The adblocking is only active when the local VPN is turned on, and it completely stops when the VPN connection is disconnected. The convenience makes it easy to access content blocked by anti-adblock scripts.
   On rooted devices, the Android app blocks ads on all web traffic including mobile networks. For non-rooted devices, ads are only blocked through a Wi-Fi connection and requires the user to set up a local proxy server for each network in order for the app to function. The app uses a local proxy server to intercept web traffic and remove ads before showing content to the user. Most of the content that users are trying to block will be removed, though some content is missed and the app is not as reliable at blocking ads as the browser versions. The app can be configured to auto-start every time the device reboots, minimizing the action required by the user.
   Advertising can be blocked by using a DNS server which is configured to block access to domains or hostnames which are known to serve ads by spoofing the address. Users can choose to use an already modified DNS server or set up a dedicated device such as a Raspberry Pi themselves. Manipulating DNS is a widely employed method to manipulate what the end user sees from the Internet but can also be deployed locally for personal purposes. China runs its own root DNS and the EU has considered the same. Google has required their Google Public DNS be used for some applications on its Android devices. Accordingly, DNS addresses / domains used for advertising may be extremely vulnerable to a broad form of ad substitution whereby a domain that serves ads is entirely swapped out with one serving more local ads to some subset of users. This is especially likely in countries, notably Russia, India and China, where advertisers often refuse to pay for clicks or page views. DNS-level blocking of domains for non-commercial reasons is already common in China.
   There are different types of ad servers. There is an ad server for publishers that helps them to launch a new ad on a website by listing the highest ads' price on its and to follow the ad's growth by registering how many users it has reached. There is an ad server for advertisers that helps them by sending the ads in the form of HTML codes to each publisher. In this way, it is possible to open the ad in every moment and make changes of frequency for example, at all times. Lastly, there is an ad server for ad networks that provides information as in which network the publisher is registering an income and which is the daily revenue.
   It is a known problem with most web browsers, including Firefox, that restoring sessions often plays multiple embedded ads at once. However, this annoyance can easily be averted simply by setting the web browser to clear all cookies and browsing-history information each time the browser software is closed. Another preventive option is to use a script blocker, which enables the user to disable all scripts and then to selectively re-enable certain scripts as desired, in order to determine the role of each script. The user thus can very quickly learn which scripts are truly necessary (from the standpoint of webpage functionality) and consequently which sources of scripts are undesirable, and this insight is helpful in visiting other websites in general. Thus by precisely controlling which scripts are run in each webpage viewed, the user retains full control over what happens on his/her computer CPU and computer screen.
   Proving click fraud can be very difficult since it is hard to know who is behind a computer and what their intentions are. When it comes to mobile ad fraud detection, data analysis can give some reliable indications. Abnormal metrics can hint at the presence of different types of frauds. To detect click fraud in the ad campaign, advertisers can focus on the following attribution points :
   Tapad is used for advertising to consumers across devices, where a user is shown an ad on their mobile or tablet device based on websites they visited on a desktop or based on a usage behavior that matches an advertiser's target audience. For example, if an Android phone visits a website shortly after a desktop PC from the same home network, Tapad will assess that there is a high probability that the two devices are operated by the same person and will show them similar ads on both devices. According to the company website, its services also include cross-device analytics for things like location, timing, user behavior, and audience analysis.
   For example, on January 7, 2014, this method would generate the domain name codice_1, while the following day, it would return codice_2. This simple example was in fact used by malware like CryptoLocker, before it switched to a more sophisticated variant.
  
  Section::::Detection.
   This data is collected without attaching the people's names, address, email address or telephone number, but it may include device identifying information such as the IP address, MAC address, cookie or other device-specific unique alphanumerical ID of your computer, but some stores may create guest IDs to go along with the data. Cookies are used to control displayed ads and to track browsing activity and usage patterns on sites. This data is used by companies to infer people's age, gender, and possible purchase interests so that they could make customized ads that you would be more likely to click on.
   Section::::Secure analytics (metering) methods.
  
  It may be good to be aware that the third-party information gathering is subject to any network limitations and security applied. Countries, Service Providers and Private Networks can prevent site visit data from going to third parties.
   The simplest technique is to check for the existence of a relevant object or property. For example, the Geolocation API (used for accessing the device’s knowledge of its geographical location, possibly obtained from a GPS navigation device) exposes a codice_1 property on the codice_2 object in the DOM; the presence of which implies the Geolocation API is supported:
  
  if ('geolocation' in navigator) {
  
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   Privacy-enhancing technologies, otherwise known as PETs, have been utilized by individuals to reduce data collection and decrease the possibility for dataveillance. PETs, such as adblocker, attempt to prevent other actors from collecting users data. In the case of adblock, the web browser extension is able to prevent the display of advertisements, which disrupts data collection about users online interactions. For businesses that may limit their opportunity to provide online users with tailored advertisements. 
   Section::::Problems with tracking.:IP address.
  
  For desktop web browsing, the network address of the client machine usually gives some form of user identification and location. For mobile web browsing, the client IP address refers to the internet gateway machine owned by the network operator. For devices such as the BlackBerry or for phones using Opera Mini browser software, the IP address refers to an operator-owned internet gateway machine in Canada or Norway.
  
  Section::::Collecting mobile web analytics data.
  