Photograph by Getty Images

Unsurprisingly, the ad blockers may retaliate.

By David Meyer
August 9, 2016

Millions of people use ad-blocking software in their browsers, with tools such as AdBlock and Adblock Plus cutting out advertisements on services that include Facebook. Well, the social network is tired of that.

Facebook fb said Tuesday that it was going to start sneaking its ads past the ad blockers’ systems, to ensure they end up in front of its users. From Wednesday, it will disguise the tell-tale technical signs that the ads on its site are ads, so the blockers cannot distinguish them from other Facebook content.

However, the social network also acknowledged the main reason why people use ad-blockers in the first place—ads can be annoying and irrelevant—by giving its users new tools to control which ads they see on Facebook.

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Facebook said it has made its ad preferences function easier to use, so people no longer have to see ads about unwanted categories of products or services. Users can also “stop seeing ads from businesses or organizations who have added them to their customer lists”—presumably a reference to Facebook’s “custom audiences” ad product.

“Rather than paying ad blocking companies to unblock the ads we show—as some of these companies have invited us to do in the past—we’re putting control in people’s hands with our updated ad preferences and our other advertising controls,” Andrew Bosworth, Facebook’s vice president for its ads and business platform, said in a statement.

Adblock Plus, which has more than 100 million active users, is one of the companies that tries to get website publishers to pay up for having their ads show up. It only asks this of the bigger players, and the ads that get through can’t be singing and dancing annoyance-fests, but it seeks a cut of around 30% from the resulting ad revenue.

According to Facebook, this model is “at best confusing to people” and responsible for defunding free services on the web, Facebook included.

Ben Williams, a spokesman for Adblock Plus, told Fortune that his company’s tool does currently block all ads on Facebook’s desktop version. However, he pointed out that the “mother lode” of Facebook’s ad revenue comes from mobile (84% according to Facebook most recent results, though desktop advertising is still a $1 billion-per-quarter business for the firm).

Services such as Adblock Plus can’t block anything in Facebook’s mobile apps. Even network-level ad-blocking technology does not currently block ads within Facebook or Twitter’s apps.

Williams confirmed that Adblock Plus has in the past spoken with Facebook, and that the social network did not end up joining its “acceptable ads” program. (Companies such as Google goog have reportedly decided to pay up.)

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Williams said it was now “a distinct” possibility that the ad-blocking community—not just the ad-blocking companies but also the open-source developers whose technology they use—will fight back, trying to enforce their blocking policies despite Facebook’s efforts.

“Facebook is just the next site in a long line of publishers and types of Internet personalities who have taken the unfortunate route of trying to go against user sentiment and engage in a cat-and-mouse game that has been played with the open source community for the last decade,” Williams said.

That said, Facebook told TechCrunch that the ad-blocking community’s technical options for overcoming Facebook’s measures would drastically slow down page-loading times for users.

Time will tell if the social network really has found a way to end this arms race.

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