In 1979, the blockbuster movie " When A Stranger Calls" was released. Jill, the goofy teenage played by Carol Kane, keeps getting phone calls from a home where she is babysitting from, a strange voice asking "Have you checked the children?" She at first thinks it's a prank, but then realizes something is really wrong. When she calls the police, they trace the call, and in the pivotal moment, the officer tells her: "The call is coming from inside the house."

The movie plays on a universal fear that the boogeyman is just upstairs. But what if the boogeyman that I try to protect my kids from when the go out into the world -- telling them to call me when they get there, or text me when they're coming home — is already inside?

The present Department of Homeland Security Secretary Jeh Johnson announced on Sunday that what we need to fear are the strangers from abroad who infiltrate through the Internet, radicalize our citizens, and set them on a course of destruction. It is a scary thought, though it shouldn't be that surprising, given that terrorists have always adapted to new means of communication. They just discovered Twitter, that's all.

What we're facing now is the blurring of what's "out there" and what's here inside. It's scary, a little hard to conceive of for people who remember a time before this utter, unbridled connectedness. You can lock your doors and set your smoke alarms, but as long as you're logged on -- and we're always "logged on" -- there are going to be forces in your home that you can't control. 

Like traditional facets of homeland security, this cyber universe can and must be managed with a few core principles that we should all make a part of our home life. And what I have always believed, what I have always known, is that the basic attributes that keep us safe at home can also keep the homeland safe.

The irony, of course, is that the home is, in cultures across the world, a sacred and separate place; a refuge from the world. But when you can access the universe from your phone -- and when the universe can access you -- well, that just isn't true anymore.

Here's what I think: the Internet IS the world -- treat it that way. Treat it like you would any trip your kids were taking without you. Set guidelines in your house about Internet use, and talk with them about it. Prepare them to be vigilant online by talking to them about what's appropriate and what's not. And above all, let them know that you are their emergency call -- their safety net -- ready to help, to talk, or just to listen.

At the end of the day, we can't shut out the world in the name of security and we wouldn't want to. The key is understanding that we live a world with risks, and we need to do what we can do to minimize them. It's a tricky balance between protecting kids and policing them. But it is one we have to engage in.

I just watched "When A Stranger Calls" again. My kids like that kind of stuff; I don't remember it being so campy.

But here's the deal: Jill, the babysitter, never checks the children after all those calls. This major omission never hit me before. Maybe now that I'm a mother, all I can think about is: How does she not check the children?

CHECK THE CHILDREN. THE CALL IS COMING FROM INSIDE THE HOUSE.

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This week on Security Mom, Juliette Kayyem checks in with her friend, fellow mom, and New York Times writer Emily Bazelon. Bazelon is also the author of " Sticks and Stones:  Defeating the Culture of Bullying and Rediscovering the Power of Character and Empathy," and she looks at the way bullying is changing in a hyperconnected world.

On 21st Century Bullying

I think a lot of us have a past image if we’re older that has more to do with physical violence. People suffered from that -- but the move toward online bullying is combined with a general move among kids toward social bullying. It's no longer socially acceptable to punch someone in the face, but schools can’t have a rule against eye rolling.

On Being Vigilant With Kids Online Time

I would not open my door at midnight in the city of New Haven and say to my kids, "Go forth, good luck, see how it goes!" In the same way, when my older son first got a phone, I tried to really think through with him: "OK, what kind of phone do you need right now? Maybe you don't need the Internet walking around in your pocket with you when you're 12 or 13 years old."

On How Online Relationships Are Different

In some ways, being on a social media site -- or online in general -- is very emotionally distancing. One of the problems we see with bullying is that kids say and do things online that they would never do in real life. They’re not looking the other person in the face, they’re not having all the cues to empathy that we’re used to. And yet, paradoxically, it is also true that these very intimate relationships can develop online and teenagers and adults alike will tell you that their IRL friends and relationships are less vivid and real to them than the ones they’re developing on Twitter or Instagram.

Security Mom is a podcast hosted by Juliette Kayyem that aims to unpack how the strange and secretive world of national security works. Subscribe to the Security Mom podcast in  iTunes.