Though he might suggest otherwise, Donald Trump's knowledge of "the cyber" appears a bit thin. But tech policy will be among the many things with which he (and his cybersecurity team) will have to grapple over the next four years.

Thus far, his tech activities have largely been limited to Twitter. But he's now at liberty to go beyond 140-character rants and suggest things that might actually become law. Here's why that has some in the tech community worried.

Surveillance State

In November 2015, the NSA was forced to stop the bulk collection of phone metadata under the terms of the USA Freedom Act. Phone metadata includes originating and terminating phone numbers, mobile subscriber identity numbers, calling card numbers, as well as time and duration of call.

Its collection made headlines in 2013 after former NSA contractor Edward Snowden released documents that detailed how government agencies got their hands on it. Officials originally defended the collection, saying that call details – like actual conversations – were not part of the metadata. But it was the scope that caught many peoples' attention. A 2013 Verizon order, for example, requested all phone data from the provider for a three-month period, which seemed excessive to some.

When asked whether he'd reinstate the metadata collection, Trump said in a November 2015 radio interview that he tends to "err on the side of security," but did not elaborate. He has not really discussed it since then, but his nominee to head the CIA, Mike Pompeo, said during a recent confirmation hearing that he supports expanding data collection.

Harsh Treatment for Whistleblowers

Federal whistleblowing is a risky proposition; just ask former NSA contractor Edward Snowden, who remains in exile in Russia after providing journalists with classified agency data. Former President Barack Obama declined to pardon Snowden before leaving office, though he did commute the sentence of Chelsea Manning, another whistleblower who provided data about the Iraq War to WikiLeaks.

"It has been my view that given [Manning] went to trial, that due process was carried out, that she took responsibility for her crime, that the sentence that she received [35 years] was very disproportionate relative to what other leakers had received and that she had served a significant amount of time, that it made sense to commute and not pardon her sentence," Obama said earlier this month.

President Trump has been critical of intelligence agency leaks, was "troubled" by Obama's Manning decision, and suggested he might support the death penalty for Snowden.

"I think Snowden is a terrible threat, I think he's a terrible traitor and you know what we used to do in the good old days when we were a strong country, you know what we used to do to traitors right?" he said on Fox & Friends in 2013.

That was, of course, before he encouraged Russia to hack his presidential opponent Hillary Clinton.

Trump has also expressed his desire to repeal the Dodd-Frank Act, which was put in place to protect the public after the financial crisis of 2008. Part of the act protects and sets up reward programs for corporate whistleblowers. While top GOP lawmakers have backed keeping those protections in place, it remains unclear if they will be altered in any way.

No More Net Neutrality

Like many of his fellow Republicans, Trump is not a fan of the FCC's net neutrality rules. After President Obama pushed the agency to reclassify broadband as a telecom service in November 2014 so the FCC could more easily regulate the industry, Trump tweeted that the move was "another top-down power grab."

On Friday, Politico reported that Trump would nominate GOP FCC Commissioner Ajit Pai to serve as chairman; Obama nominee Tom Wheeler stepped down as chairman that day.

Pai has opposed the FCC's net neutrality rules, arguing that they will "raise consumers' broadband bills, slow broadband speeds, and reduce competition." Net neutrality is the idea that ISPs cannot discriminate based on content. For the most part, both sides of the aisle agree with that sentiment, but they disagree over whether the feds should monitor compliance. For his part, Pai argues that the FCC should only step in if there is "proof of market failure."

Trump, meanwhile, has selected FCC advisers who aren't exactly big fans of the agency's work.

Muslim Registry

In November 2015, Trump was asked if "we might need to register Muslims in some type of database, or note their religion on their ID." He responded that "We're going to have to look at a lot of things very closely." Shortly thereafter, Trump was asked on a rope line in Iowa whether he supported a database for Muslims. "I would certainly implement that. Absolutely," Trump told NBC's Vaughn Hillyard.

George W. Bush implemented a similar system after 9/11, though it only applied to immigrant men from predominantly Muslim countries, not American citizens. But it was widely regarded as ineffective, and the Obama administration scrapped it last year.

Talk of a registry under Trump, however, is a chilling prospect for many, given that he supported a "total and complete shutdown of Muslims entering the United States." Tech employees pledged not to build such a registry, but the industry has a shady track record when it comes to colluding with repressive regimes.

The largest shareholder of powerful data-mining firm Palantir, for example, is Peter Thiel, a member of Trump's transition team and a contributor to his campaign. Palantir has been under media scrutiny for a while for its secretive practices, but now tech workers in Silicon Valley are concerned about what it might do at the behest of President Trump.

This article originally appeared on PCMag.com.