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.
Features
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: s - 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
Interesting Possible Uses
Time-based constraints such as parental controls to block a site, e.g. Facebook. Logging of site usage e.g. company notifications
Challenges
Testing
Two phases of testing was completed.
- 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.
- 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.
DNS-Sec
No effort made to handle or respond to DNS-Sec challenges.
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