President Trump on Monday signed a resolution that rolls back internet privacy regulations adopted in October under the Obama administration.

The Federal Communications Commission rule, scheduled to take effect later this year, was designed to give consumers greater control over how internet service providers such as Charter, Comcast, AT&T and Verizon share information.

Essentially, it would have prohibited internet service providers from selling information about your online activities to advertisers. It would have required explicit consent from consumers if data were to be shared or sold.

The ISPs said the Obama administration measure was unfair, since Google and Facebook, among others, already sell information to third parties. But consumer groups argued that while customers can stay away from certain websites, they have little choice when it comes to ISPs.

The legislation signed by the president, in effect, preserves the status quo. Currently, even though it’s permitted, most ISPs don’t sell customer data to advertisers.

But with the door now clearly open, that likely will change. And the tactics used could become more aggressive and invasive. Also, because it came in the form of a Congressional Review Act resolution, the new legislation prevents the FCC from putting any similar restrictions in place in the future.

In January, all the major ISPs promised that if they start selling private data, they’ll give customers a chance to opt out. But how, or when, that option will present itself, remains unclear. It could be as obscure as a single email, or a little-noticed website posting.

Customers who don’t want their ISPs sharing information will have be vigilant about seizing the chance to opt out.