Hacking your apartment's electronic entry system | Hacker News Reader

Hacking your apartment's electronic entry system

jmtame.posterous.com

72 pointsjmtame35 comments

I actually implemented this idea using Twilio almost a year ago and have been using it actively ever since. I give my close friends 4-digit PIN numbers to my condo. When someone dials my number in the directory, it first prompts them for a PIN. If they enter a valid PIN, it welcomes them by name (my friends love this) and unlocks the door. If they enter an invalid PIN or no PIN, Twilio rings my and both my roommates' cell phones and connects to whomever answers first.

I also can create one-time-use PINs and one-day-only PINs for parties or whatnot.

As an extra plus, I used to have a home phone because my intercom requires local phone numbers. Since I built my "doorman," I don't need it.

Any particular reason you haven't turned this into a startup?

I was going to ask the same question

Mostly time at this point, but I also wasn't sure if there would be interest. I should have some more free time this spring... maybe I'll work to get an MVP out then? I'll let y'all know.

I would buy it! You could charge per-usage too, since most people don't have an unlimited stream of people coming to their apartment every month.

I'm not sure how the phone # allocation works but I imagine the biggest challenge is getting local #'s for people who don't have google voice or whatnot.

I applied to YC with this exact idea, and didn't get in. Of course, there are a lot of factors- but I guess it was an idea they didn't love.

http://www.getdoorman.com/ (Not really coming soon anymore :) )

You can do this a wee bit more securely than "Let anybody in", too. Ten minutes of work and you can give your script state, letting it do things like e.g. accept a text message or web interface request to let anyone in for the next ten minutes.

I was considering implementing Port Knocking 2.0 on my server(s) for giggles: permit SSH logins without a key for ten minutes after calling a number and keying in a password. (I have had to do emergency maintenance from net cafes before, which is unfun in the best of circumstances. Being unable to login just makes it even more unfun.)

I've thought about this - when I get time, I want to implement this into my system. Know someone is about to come over? Go ahead and let them in advance. Maybe even leave a message for them for the phone to read when they get there.

I guess you regen ssh keys after accessing your server from a cafe?

Danielle Morrill of Twilio shared something very similar to this on her blog back in June of 2010. One difference in her post is the fact that she set up different secret codes for various roommates.

Link: http://www.daniellemorrill.com/2010/06/how-i-built-a-multi-u...

I'm sorry to be pedantic, but please use capital letters where needed. I found it rather difficult to read...

Weird, I didn't even notice the lack of capitals until you pointed it out. I wonder if it's because of all the AIM I did during my formative years.

Why do you want to disable the locking of the exterior doors of your apartment building at night? You still can't legitimately enter your apartment without keys, but observant criminals can come in and force your interior door without worrying nearly as much about passersby.

They used the same gate system at my last apartment. It was pretty useless. I had two other roommates and guests would come over all the time, so my phone was always going off. I had a special ringtone when I got a call from the gate and when I heard it, I would just hit 9 reflexively without even thinking about it. I was surely not the only one in the complex to do this -- so if you wanted to get in all you had to do was dial one apartment after the other until somebody let you in without questioning you.

Would putting the MP3 on your phone and playing it into the entrypads mic get you in as well? I'm picturing waling up to any apartment building, choosing an apartment number at random, and then just playing the MP3 when someone answers (or when voicemail picks up.)

I doubt it. It's listening for the 9 tone on the other end and I think it can distinguish between the two.

This reminds me of a hack we did in my freshman dorm though... we cut the wire from a card reader to a washing machine and recorded the signal the reader sent. Then reconnected the card reader to the washer in parallel with an 1/8inch audio jack. The folks who were in the know would plug their iPod into the audio jack on the back of the washer, play the "free laundry" mp3, and get a free load of laundry.

I was thinking of doing this with my answering machine, simply put the '9' MP3 at the beginning or end of my message so that if my wife isn't in and I forget/lose my keys that I can still get in the building.

Although it's a little redundant as I know so many people in the building that I'd probably be let in before the voicemail played the right tone. Plus my in-laws aren't a far walk for me to crash on their spare bed or pick up my spare set of keys.

However, I basically just want to do it to see if it works.

I'm sure some systems are vulnerable to this (although the mic might mangle the DTMF). After all until the late 80s the entire phone system was vulnerable to these kinds of attacks because it used in-band signaling

http://en.wikipedia.org/wiki/Blue_box

What's the deal with all lowercase? Totally unreadable.

Maybe written by a cockroach?

Just wanted to say that this reference made my day. My grandfather introduced me to Archy several years ago, and I have yet to find anyone else that knows about him.

and so I don't get downvoted for a comment with no substance, if you don't get the reference, try googling "archy and mehitabel"

link: http://en.wikipedia.org/wiki/Archy_and_mehitabel

I half expected to get downvoted for the obscure comment myself, but decided, it's worth it! ;)

Glad to see it caught a few knowing eyes, after all!

I wouldn't go so far as to say unreadable, more like annoying. Hopefully he takes this into consideration for the book he's writing.

someone else is doing the editing, for good reasons =]

An apartment I lived in had a similar system. I noticed that the caller ID showed what appeared to be a valid number. So one day I tried calling it while at the door... when it started ringing, I started hitting buttons on the keypad (on the door) and when I hit the # key (or maybe it was *), it picked up. I was then able to dial 9 from my phone, and it let me in.

I no longer live there, and don't have access to an apartment that has one. I'd be interested to see if that works on other systems. If anyone wants to try, let me know if it does.

I just realized that my system appears to work the same way. I always wondered why the caller ID showed a different number for my buzzer from the rental company main lines, so I'll have to program it into my cell phone and see if this works for me.

Great insight, my mind never jumped to this idea. I was thinking of putting the '9' tone on my answer machine.

when I was in college, I sublet an apartment where we had like 8 people living there for the summer and only 3 keys to the front gate. I solved the problem of getting buzzed up when no-one had keys by pressing 9 at the end of the outgoing message on the answering machine. Call the apt on the box and if no one was home we could still get in.

Or just press the digit at the begining of your voicemail.

That was my idea for this trick, I was wondering if the sound would come out too distorted to trigger the system.

I did something similar with Google Voice. I created a new voicemail greeting of the tone and calls from the apartment's callbox are sent straight to voicemail with that greeting.

You have to hold your phone next to the speakers on my computer and record the greeting by playing the tone since the tone you get from pressing the number on your phone isn't picked up by Google Voice, for whatever reason.

I did this many years back with my work's phone system and an unused DID. Pro-Tip: Make a phone tree. 1 calls your cell, 2 calls your roommates cell, and pressing a secret key like 6 dials your 9 response.

Huh. @koush had this idea a few days ago: http://twitter.com/#!/koush/status/39435576788647936

A service similar to this was built and, sadly, already hit the deadpool: http://buzzer-o-matic.tumblr.com/.

I tweeted about mine when I built it: http://twitter.com/#!/caryme/status/10094156341

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