gobdns

A simple, dynamic dns server written in go. It can direct all requests for an address, or addresses matching *.<address> or *-<address> to a particular ip.

For example, if you set brian.turtles.com to point to 127.0.0.5, then all these domains will get directed at that address:

• brian.turtles.com
• foo.brian.turtles.com
• bar-brian.turtles.com
• foo-bar.brian.turtles.com

and so on. This is useful for setting up development environments for multiple employees, each one maybe having multiple virtual hosts.

Features

• TCP and UDP support
• Easy to setup
• Prefix-wildcard matching of requests (most specific wins)
• Simple REST api for retrieving and modifying entries
• Disk persistence
• Basic master/slave replication
• Can forward requests for unknown domains to a different nameserver
• Can forward requests with particular suffixes to particular nameservers
• Can forward request for domain to a different nameserver as a different domain

Building

First, clone the repo.

To build the web console stuff you'll need elm 0.13 installed and on your path. Run the following to install the elm dependencies:

cd http/console
elm-get install

Then to get the go dependencies:

# Installs the go-bindata binary
go get github.com/jteeuwen/go-bindata/...

# Retrieves dependencies for this project
go get ./...

After that:

# Build the gobdns binary
make clean all

Usage

Running

Run ./gobdns --example to output the default configuration. This can be piped to a file, modified and used with the --config flag.

Adding entries

Once running, you can use the REST api or the web console to add and remove entries.

You can access the web console by going to the address specified by --api-addr (localhost:8080 by default).

Here are example curl calls for all the api methods:

See all existing entries:

curl -i localhost:8080/api/domains/all

Set foo.turtles.com to point to whatever ip the server sees the request coming from:

curl -i -XPOST localhost:8080/api/domains/foo.turtles.com

Set bar.turtles.com to point to 127.0.0.5:

curl -i -XPOST -d'127.0.0.5' localhost:8080/api/domains/bar.turtles.com

Delete the foo.turtles.com entry:

curl -i -XDELETE localhost:8080/api/domains/foo.turtles.com

Persistence

If backup-file is set (it is by default) then every second a snapshot of the current data set will be written to disk. On startup (again, if backup-file is set) this file will be read in if it exists and used as the initial set of mappings.

Replication

master-addr can be set to point to the REST interface of another running gobdns instance, and every 5 seconds will pull the full list of entries from that instance and overwrite the current list.

Forwarding

When the --forward-addr option is used it can be set in order to proxy requests for unmatched domains to another dns resolver.

If the target for a hostname isn't an ip but instead another hostname, a request for that target hostname will be sent to the --forward-addr server and that response will be sent back to the client.

When the --forward-suffix-addr option is used all requests which are not matched by any targets set directly on the gobdns instance and which match the suffix will be forwarded to that dns server. It can be specified more than once to attempt to match multiple suffixes. The request will fallback to --forward-addr (if set) if no suffixes match.