# Uninstrumented Gateways/Proxies

The uninstrumented gateways are not instrumented by SkyWalking agent plugin when they are started,
but they can be configured in `gateways.yml` file or via [Dynamic Configuration](dynamic-config.md). The reason why they can't register
to backend automatically is that there're no suitable agent plugins, for example, there is no agent plugins for Nginx, haproxy, etc.
So in order to visualize the real topology, we provide a way to configure the gateways/proxies manually.

## Configuration Format

The configuration content includes the gateways' names and their instances:

```yml
gateways:
 - name: proxy0 # the name is not used for now
   instances:
     - host: 127.0.0.1 # the host/ip of this gateway instance
       port: 9099 # the port of this gateway instance, defaults to 80
```

**Note** that the `host` of the instance must be the one that is actually used in client side, for example,
if the instance `proxyA` has 2 IPs, say `192.168.1.110` and `192.168.1.111`, both of which delegates the target service,
and the client connects to `192.168.1.110`, then configuring `192.168.1.111` as the `host` won't work properly.