Show HN: A simple-to-update dynamic DNS service | Hacker News Reader

Show HN: A simple-to-update dynamic DNS service

dhcp.io

30 pointsstevekemp27 comments

Nice! Setting up my server to update every hour was as simple as:

   crontab -e

and adding the line:

   31 * * * * curl http://dhcp.io/set/99351a76-f6...

(the above job will run on the 31st minute of every hour)

Cool.

I suspect that you'll want to hide STDOUT, if not STDERR. If you're ever dual-homed you might also want to consider adding an explicit "-4", or "-6" in there.

Do you really want to have to wait up to an hour if your IP address changes and you're away from home?

I wonder if there's any utilities that use UPnP or NAT-PMP to monitor for an address change and invoke a script when one is detected.

Last time I did this on Linux, it was in an if.up script, so when the PPP interface comes up it updates the DNS.

CloudFlare has a (free) DNS api too. Pretty easy to script something with their system. https://www.cloudflare.com/docs/client-api.html

Very cool. If anybody needs a Python implementation: https://gist.github.com/anonymous/02257ea2ccf776c1a32e

Simple and to the point. Truth be told I've always wanted something like this for my own domains, so that I can point to a home machine, but was too lazy to set it up. Thanks for throwing this out here!

You're welcome.

Initially it was put together as a learning experience, but I can see that it is useful enough to remain live indefinitely.

I can imagine several way of monetizing it, such as adding the MX/SRV/TXT/CNAME records, etc. But the one that seems most useful would be allowing custom domain - and sadly I can't see how to do that easily.

(I can't imagine somebody would trust me with their root-domain, basically. And having *.foo.example.com seems like it would be long enough to spoil the utility.)

I can't imagine somebody would trust me with their root-domain, basically.

The “root-domain” is the domain name with a single zero-length label at the top of the hierarchy. What you're referring to is a zone.

I thought context would make that clear, but yes you're correct.

Yes it is from the context that I inferred what you're talking about. I didn't mention it to pick, but because the DNS is littered with misunderstandings and I think that's part of what holds it back.

Thanks for building this! I set up something like this with dyndns for my Raspberry Pi, but thought it was silly that I had to log in every n days to keep the account active.

Can you open source this? Would be great for other people wanting to run similar services.

From http://dhcp.io/faq/

> But either way if you find this service useful you can clone the source-code from Github[0], and run your own instance.

[0]: https://github.com/skx/dhcp.io/

As per the other reply, this is open.

Can I ask why you want it to be open though? Do you not trust the site/me to exist in the future? Or do you not want to rely on something external?

How do you handle ipv4/ipv6? Seems this is listing my ipv4 address, but not ipv6...

It's in the FAQ, you use the -4 or -6 parameters to curl to force it to connect one way or the other, and that controls which address gets updated.

(Of course your IPv6 connectivity to dhcp.io has to work properly, but it certainly works both ways for me).

Why didn't anyone build this before?

Serious question? People build them all the time. They don't tend to stay simple or they eventually start demanding payment. It seems like this is a low cost thing to run, but if it takes off it gets very expensive.

I'm hosting the actual records on Amazons Route53 so it is very low cost to run.

That said I am looking at monetizing, via additions which require either a low yearly fee, or a lifetime membership price (low).

The hard part is seeing what people will consider useful enough. One name for free, without monthly logins being required must always be true.

But I could imagine raising the standard TTL to 600 seconds, and keeping 60s for the premium users, adding MX record support, etc.

I've been involved with a number of DNS related companies and projects.

Your biggest cost sink will be abuse. Some peddler of illicit images or terror group will set up camp, Amazon will take down all of your records. You'll realize you need to run your own infrastructure. You setup a few boxes. Someone starts selling fake rolexes and your boxes get taken offline. You move them to a friendlier host. A HYIP gets setup under your domain and they don't pay someone, which results in a 150 Gbps DDoS attack. The FBI shows up. You get cynical dealing with the lowest scum of the internet on a regular basis. People are constantly asking for new features and unwilling to pay. You're funding the whole thing out of pocket. Eventually Dyn shows up and offers to take the whole thing off your hands. A year later they shut it down. Some guy on Hacker News announces some Dynamic DNS or free DNS hosting provider, and you smirk to yourself.

This. Abuse causes a huge headache and will drain resources. If you are sincerely interested in offering this, provide a great value and feature set but charge enough to keep the garbage out..its a catch 22 in that having a higher price keeps the service profitable but having a higher price also means possibly never gaining traction. If you ever figure out how to solve that problem scrap this and open up a business selling that solution :)

You paint a scary picture.

I did evaluate a couple of potentially negative outcomes, but they largely boiled down to Amazon dropping the domain, or having a sudden influx of faked traffic resulting in large bills.

I will keep a more cautious eye out ..

I can't emphasis enough for you to pay attention to what the folks above have said.

I also have some experience with a large DNS service and you just wouldn't believe the amount of time and resources that get allocated to dealing with abuse.

Yep, this is basically what I meant.

I mean, I applaud the good intentions and I sure would love for there to be a good and stable public dyndns solution, but history is not on side with that outcome unfortunately. :(

Yes, it was a serious question. Because I was suspecting there was some problem behind this (I just didn't know it was serious as you and the other people explained).

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