The first concept is the integration of BunkerWeb into the target environment. We prefer to use the word "integration" instead of "installation" because one of the goals of BunkerWeb is to integrate seamlessly into existing environments.
The following integrations are officially supported :
If you think that a new integration should be supported, do not hesitate to open a [new issue](https://github.com/bunkerity/bunkerweb/issues) on the GitHub repository.
The configuration of BunkerWeb is done by using what we call the "settings" or "variables". Each setting is identified by a name such as `AUTO_LETS_ENCRYPT` or `USE_ANTIBOT`. You can assign values to the settings to configure BunkerWeb.
The complete list of available settings with descriptions and possible values is available in the [settings section](/1.4/settings) of the documentation.
The multisite mode is a crucial concept to understand when using BunkerWeb. Because the goal is to protect web applications, our solution is intrinsically linked to the concept of "virtual host" or "vhost" (more info [here](https://en.wikipedia.org/wiki/Virtual_hosting)) which makes it possible to serve multiple web applications from a single (or a cluster of) instance.
By default, the multisite mode of BunkerWeb is disabled which means that only one web application will be served and all the settings will be applied to it. The typical use case is having a single application to protect : you don't have to worry about the multisite and the default behavior should be the right one for you.
When multisite mode is enabled, BunkerWeb serves and protects multiple web applications. Each web application is identified by a unique server name and have its own set of settings. The typical use case is having multiple applications to protect and you want to use a single (or a cluster depending of the integration) instance of BunkerWeb.
Each setting has a context that defines "where" it can be applied. If the context is global then the setting can't be set per server (or "per site", "per app") but only to the whole configuration. Otherwise, if the context is multisite, the setting can be set globally and per server. Defining a multisite setting to a specific server is done by adding the server name as a prefix of the setting name like `app1.example.com_AUTO_LETS_ENCRYPT` or `app2.example.com_USE_ANTIBOT` for example. When a multisite setting is defined globally (without any server prefix), all the servers will inherit that setting (but can still be overriden if we set the same setting with the server name prefix).
You will find concrete examples of multisite mode in the [quickstart guide](/1.4/quickstart-guide) of the documentation and the [examples](https://github.com/bunkerity/bunkerweb/tree/master/examples) directory of the repository.
Because meeting all the use cases only using the settings is not an option (even with [external plugins](/1.4/plugins)), you can use custom configurations to solve your specific challenges.
Under the hood, BunkerWeb uses the notorious NGINX web server, that's why you can leverage its configuration system for your specific needs. Custom NGINX configurations can be included in different [contexts](https://docs.nginx.com/nginx/admin-guide/basic-functionality/managing-configuration-files/#contexts) like HTTP or server (all servers and/or specific server block).
Another core component of BunkerWeb is the ModSecurity Web Application Firewall : you can also use custom configurations to fix some false positives or add custom rules for example.
You will find concrete examples of custom configurations in the [quickstart guide](/1.4/quickstart-guide) of the documentation and the [examples](https://github.com/bunkerity/bunkerweb/tree/master/examples) directory of the repository.
