coredhcp
Fast, multithreaded, modular and extensible DHCP server written in Go
This is still a work-in-progress
Example configuration
In CoreDHCP almost everything is implemented as a plugin. The order of plugins in the configuration matters: every request is evaluated calling each plugin in order, until one breaks the evaluation and responds to, or drops, the request.
The following configuration runs a DHCPv6-only server, listening on all the interfaces, using a custom DUID-LL as server ID, and reading the leases from a text file.
server6:
listen: '[::]:547'
plugins:
- server_id: LL 00:de:ad:be:ef:00
- file: "leases.txt"
# - dns: 8.8.8.8 8.8.4.4 2001:4860:4860::8888 2001:4860:4860::8844
#server4:
# listen: '0.0.0.0:67'
# plugins:
# - server_id: 10.10.10.1
# - dns: 8.8.8.8 8.8.4.4
# - router: 10.10.10.1
# - netmask: 255.255.255.0
# - range: leases.txt 10.10.10.100 10.10.10.200 60s
See also config.yml.example.
Build and run
An example server is located under cmds/coredhcp/, so enter that
directory first. To build a server with a custom set of plugins, see the "Server
with custom plugins" section below.
Once you have a working configuration in config.yml (see config.yml.example), you can build and run the server:
$ cd cmds/coredhcp
$ go build
$ sudo ./coredhcp
INFO[2019-01-05T22:28:07Z] Registering plugin "file"
INFO[2019-01-05T22:28:07Z] Registering plugin "server_id"
INFO[2019-01-05T22:28:07Z] Loading configuration
INFO[2019-01-05T22:28:07Z] Found plugin: `server_id` with 2 args, `[LL 00:de:ad:be:ef:00]`
INFO[2019-01-05T22:28:07Z] Found plugin: `file` with 1 args, `[leases.txt]`
INFO[2019-01-05T22:28:07Z] Loading plugins...
INFO[2019-01-05T22:28:07Z] Loading plugin `server_id`
INFO[2019-01-05T22:28:07Z] plugins/server_id: loading `server_id` plugin
INFO[2019-01-05T22:28:07Z] plugins/server_id: using ll 00:de:ad:be:ef:00
INFO[2019-01-05T22:28:07Z] Loading plugin `file`
INFO[2019-01-05T22:28:07Z] plugins/file: reading leases from leases.txt
INFO[2019-01-05T22:28:07Z] plugins/file: loaded 1 leases from leases.txt
INFO[2019-01-05T22:28:07Z] Starting DHCPv6 listener on [::]:547
INFO[2019-01-05T22:28:07Z] Waiting
2019/01/05 22:28:07 Server listening on [::]:547
2019/01/05 22:28:07 Ready to handle requests
...
Then try it with the local test client, that is located under
cmds/client/:
$ cd cmds/client
$ go build
$ sudo ./client
INFO[2019-01-05T22:29:21Z] &{ReadTimeout:3s WriteTimeout:3s LocalAddr:[::1]:546 RemoteAddr:[::1]:547}
INFO[2019-01-05T22:29:21Z] DHCPv6Message
messageType=SOLICIT
transactionid=0x6d30ff
options=[
OptClientId{cid=DUID{type=DUID-LLT hwtype=Ethernet hwaddr=00:11:22:33:44:55}}
OptRequestedOption{options=[DNS Recursive Name Server, Domain Search List]}
OptElapsedTime{elapsedtime=0}
OptIANA{IAID=[250 206 176 12], t1=3600, t2=5400, options=[]}
]
...
Plugins
CoreDHCP is heavily based on plugins: even the core functionalities are
implemented as plugins. Therefore, knowing how to write one is the key to add
new features to CoreDHCP.
Core plugins can be found under the plugins directory. Additional
plugins can also be found in the
coredhcp/plugins repository.
Server with custom plugins
To build a server with a custom set of plugins you can use the
coredhcp-generator tool. Head there for
documentation on how to use it.
How to write a plugin
The best way to learn is to read the comments and source code of the
example plugin, which guides you through the implementation
of a simple plugin that prints a packet every time it is received by the server.