---
title: "Transports"
description: "Learn more about customizing how the Sentry SDK sends data to Sentry."
url: https://docs.sentry.io/platforms/native/configuration/transports/
---

# Transports | Sentry for Native

The Native SDK uses *Transports* to send event payloads to Sentry. The default transport depends on the target platform:

* **Windows**: WinHTTP
* **Linux**: Curl
* **macOS**: Curl

## [Custom Transports](https://docs.sentry.io/platforms/native/configuration/transports.md#custom-transports)

To specify a custom transport, use the `sentry_options_set_transport` function and supply a transport that implements the `sentry_transport_t` interface.

```c
#include <sentry.h>

void custom_transport(sentry_envelope_t *envelope, void *state) {
  /*
   * Send the event here. If the transport requires state, such as an HTTP
   * client object or request queue, it can be specified in the `state`
   * parameter when configuring the transport. It will be passed as second
   * argument to this function.
   * The transport takes ownership of the `envelope`, and must free it once it
   * is done.
   */
  sentry_envelope_free(envelope);
}

int main(void) {
  void *transport_state = 0;

  sentry_options_t *options = sentry_options_new();
  sentry_transport_t *transport = sentry_transport_new(custom_transport);
  sentry_transport_set_state(transport, transport_state);

  sentry_options_set_transport(options, transport);
  sentry_init(options);

  /* ... */
}
```

The transport is invoked in the same thread as the call to `sentry_capture_event`. Consider to offload network communication to a background thread or thread pool to avoid blocking execution.

## [Using a Proxy](https://docs.sentry.io/platforms/native/configuration/transports.md#using-a-proxy)

The Native SDK allows the configuration of an `HTTP` (`CONNECT`) or `SOCKS5` proxy through which requests can be tunneled to our backend. It can be configured manually via the following option interface:

```c
sentry_options_t *options = sentry_options_new();
sentry_options_set_proxy(options, "http://my.proxy:8080");
sentry_init(options);

/* ... */
```

The same function can also be used for the `SOCKS5` proxy:

```c
sentry_options_t *options = sentry_options_new();
sentry_options_set_proxy(options, "socks5://my.proxy:1080");
sentry_init(options);

/* ... */
```

### [Proxy behavior](https://docs.sentry.io/platforms/native/configuration/transports.md#proxy-behavior)

We support `HTTP` proxies on all platforms, and `SOCKS5` proxies on Linux and macOS. On Windows, `https` proxy servers are not supported by the default transport (WinHTTP). The proxy may also contain authentication (`"http://user:password@my.proxy:8080"`) or be written in IPv6 format (`"http://[::1]:8080"`).

The SDK will always automatically configure the HTTP proxy if a corresponding environment variable is set. Depending on the [DSN](https://docs.sentry.io/concepts/key-terms/dsn-explainer.md) protocol, the matching `http(s)_proxy` environment variable is read. So for a usual Sentry-hosted `DSN`, you must set the `https_proxy` variable .

If you don't want the SDK to configure the HTTP proxy from the environment variables automatically, you can set the proxy option to an empty string value:

```c
sentry_options_t *options = sentry_options_new();
sentry_options_set_proxy(options, "");
sentry_init(options);

/* ... */
```