MiniDynDNS

November 6th, 2015 ruby, dns, http, network, programming, minidyndns

During the last few weeks I've been working on a small, simple and self-contained dynamic DNS server: MiniDynDNS. A friend of mine wanted to bring one of his computers online but didn't want to use an 3rd party service like DynDNS.

Well, you probably know the typical hacking answer: "Why not build something like that ourselves?". How hard can it be? After all we only need a hash table or dictionary for a simple DNS server. Throw in some code to parse and generate DNS packets and your're done.

After a bit of hacking and testing it actually worked. An HTTP interface would be nice so I can tell my router to report changed IPs by itself. So in it went.

You can probably imagine that the result was a funny but scary bit of code. I did some cleanup and ended up with about 600 lines of Ruby. Some more refactoring into several classes resulted into a bit to much glue code for my taste so I reverted back to simple procedural style. The code isn't pretty or fancy but it's easier to understand this way I hope.

So if you want to role your own little DynDNS for your private stuff, take a look. Maybe it's what you want. But remember: It's only build for small stuff, not high-traffic sites. 🙂

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#1 by Chris February 16th, 2018 10:55

Hi there,

Chris is calling again :-)

Your minidyndns is working fine since months. Many thanks for that coding. I'd like contribute a patch to update ips more easy. Normally, the client updates it's own public ip. So why the client first has to find out which is his public ip. Instead, the client should tell the server: Update my IP with my current public ip.

So if no myip parameter is provided, use remote-ip.

I'm not a ruby-hacker, so I don't know if this is good code, but it works for me :-)
```
cp:/opt/minidyndns# diff dns-14.rb dns.rb 
481c481,484
<   
---
> 
>   cp_sock_domain, cp_remote_port, cp_remote_hostname, cp_remote_ip = connection.peeraddr
>   log "#{cp_remote_ip} calling for update"    
> 
492c495
<       throw :status, :bad_request unless params["myip"]
---
>       # throw :status, :bad_request unless params["myip"]
494c497,502
<       ip_as_string = CGI::unescape params["myip"].first
---
>       if params.include? 'myip'
>           ip_as_string = CGI::unescape params["myip"].first
>       else
>           ip_as_string = cp_remote_ip
>       end
> 
```
Bye,
Chris
react

nice meh bad surprised confused agree disagree
- #2 by Stephan reply to #1 February 19th, 2018 14:56
  
  Hi Chris,
  
  That's a really neat idea. Thanks for sharing it and providing a patch. 🙂 Would have solved some trouble I had a while ago. I've implemented it based on your patch, updated the documentation and released it as v1.2.0.
  
  If you want to use it you just have to download the new dns.rb file.
  
  Happy programming
  Stephan
  react
  
  nice meh bad surprised confused agree disagree