| *prouter* | a physical router, having the same default services as the *router* node type; for incorporating Linux testbed machines into an emulation. |
Configuration files can be automatically generated by each service. For
example, CORE automatically generates routing protocol configuration for the
router nodes in order to simplify the creation of virtual networks.
To change the services associated with a node, double-click on the node to
invoke its configuration dialog and click on the *Services...* button,
or right-click a node a choose *Services...* from the menu.
Services are enabled or disabled by clicking on their names. The button next to
each service name allows you to customize all aspects of this service for this
node. For example, special route redistribution commands could be inserted in
to the Quagga routing configuration associated with the zebra service.
To change the default services associated with a node type, use the Node Types
dialog available from the *Edit* button at the end of the Layer-3 nodes
toolbar, or choose *Node types...* from the *Session* menu. Note that
any new services selected are not applied to existing nodes if the nodes have
been customized.
The node types are saved in the GUI config file **~/.coregui/config.yaml**.
Keep this in mind when changing the default services for
existing node types; it may be better to simply create a new node type. It is
recommended that you do not change the default built-in node types.
## New Services
Services can save time required to configure nodes, especially if a number
of nodes require similar configuration procedures. New services can be
introduced to automate tasks.
### Creating New Services
1. Modify the example service shown below
to do what you want. It could generate config/script files, mount per-node
directories, start processes/scripts, etc. Your file can define one or more
classes to be imported. You can create multiple Python files that will be imported.
2. Put these files in a directory such as ~/.coregui/custom_services
Note that the last component of this directory name **myservices** should not
be named something like **services** which conflicts with an existing module.
3. Add a **custom_config_services_dir = ~/.coregui/custom_services** entry to the
/etc/core/core.conf file.
**NOTE:**
The directory name used in **custom_services_dir** should be unique and
should not correspond to
any existing Python module name. For example, don't use the name **subprocess**
or **services**.
4. Restart the CORE daemon (core-daemon). Any import errors (Python syntax)
should be displayed in the terminal (or service log, like journalctl).
5. Start using your custom service on your nodes. You can create a new node
type that uses your service, or change the default services for an existing
node type, or change individual nodes. .
### Example Custom Service
Below is the skeleton for a custom service with some documentation. Most
people would likely only setup the required class variables **(name/group)**.
Then define the **files** to generate and implement the
**get_text_template** function to dynamically create the files wanted. Finally,
the **startup** commands would be supplied, which typically tend to be
