Fully functional DNS server written in C#.

The project was conceived while working to reduce the cost of datacentre "stamps" while providing robust services within a datacentre, specifically to remove the need for an expensive load-balancer device by providing round-robin DNS services, and retrying connectivity instead.

This software is licenced under MIT terms that permits reuse within proprietary software provided all copies of the licensed software include a copy of the MIT License terms and the copyright notice. See licence.txt

// clone the repo
>> cd $repo-root
>> git clone https://github.com/stephbu/csharp-dns-server

// check you can build the project
>> cd $repo-root/csharp-dns-server
>> dotnet build

// check that the tests run
>> dotnet test

• if you're running on Windows 10 with Docker Tools installed, Docker uses the ICS SharedAccess service to provide DNS resolution for Docker containers - this listens on UDP:53, and will conflict with the DNS project. Either turn off the the service (net stop SharedAccess), or change the UDP port.

As written, the server has the following features:

• Pluggable Zone Resolver. Host one or more zones locally, and run your code to resolve names in that zone. Enables many complex scenarios such as:
• round-robin load-balancing. Distribute load and provide failover with a datacentre without expensive hardware.
• health-checks. While maintaining a list of machines in round-robin for a name, the code performs periodic healthchecks against the machines, if necessary removing machines that fail the health checks from rotation.
• Delegates all other DNS lookup to host machines default DNS server(s)

The DNS server has a built-in Web Server providing operational insight into the current server behaviour.

• healthcheck for server status
• counters
• zone information

Time-based constraints such as parental controls to block a site, e.g. Facebook. Logging of site usage e.g. company notifications

Two phases of testing was completed.

1. Verification that the bit-packing classes correctly added and removed bits in correct Endian order, complicated by network bitpacking in reverse order to Windows big-endian packing.

2. Protocol verification - that well known messages were correctly decoded and re-encoded using the bit-packing system.

Much time was spent using Netmon to capture real DNS challenges and verify that the C# DNS server responded appropriately.

No effort made to handle or respond to DNS-Sec challenges.

Pull Requests, Bug Reports, and Feature Requests are most welcome.

Suggested workflow for PRs is

1. Make a fork of csharp-dns-server/master in your own repository.
2. Create a branch in your own repo to entirely encapsulate all your proposed changes
3. Make your changes, add documentation if you need it, markdown text preferred.
4. Squash your commits into a single change (Find out how to squash here)
5. Submit a PR, and put in comments anything that you think I'll need to help merge and evaluate the changes

All contributions must be licenced under the same MIT terms, do include a header file to that effect.