---
title: Stream Proxy
---

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A stream proxy operates at the transport layer, handling stream-oriented traffic based on TCP and UDP protocols. TCP is used for many applications and services, such as LDAP, MySQL, and RTMP. UDP is used for many popular non-transactional applications, such as DNS, syslog, and RADIUS.

APISIX can serve as a stream proxy, in addition to being an application layer proxy.

## How to enable stream proxy?

By default, stream proxy is disabled.

To enable this option, set `apisix.proxy_mode` to `stream` or `http&stream`, depending on whether you want stream proxy only or both http and stream. Then add the `apisix.stream_proxy` option in `conf/config.yaml` and specify the list of addresses where APISIX should act as a stream proxy and listen for incoming requests.

```yaml
apisix:
  proxy_mode: http&stream  # enable both http and stream proxies
  stream_proxy:
    tcp:
      - 9100 # listen on 9100 ports of all network interfaces for TCP requests
      - "127.0.0.1:9101"
    udp:
      - 9200 # listen on 9200 ports of all network interfaces for UDP requests
      - "127.0.0.1:9211"
```

If `apisix.stream_proxy` is undefined in `conf/config.yaml`, you will encounter an error similar to the following and not be able to add a stream route:

```
{"error_msg":"stream mode is disabled, can not add stream routes"}
```

## How to set a route?

You can create a stream route using the Admin API `/stream_routes` endpoint. For example:

:::note
You can fetch the `admin_key` from `config.yaml` and save to an environment variable with the following command:

```bash
admin_key=$(yq '.deployment.admin.admin_key[0].key' conf/config.yaml | sed 's/"//g')
```

:::

```shell
curl http://127.0.0.1:9180/apisix/admin/stream_routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
    "remote_addr": "192.168.5.3",
    "upstream": {
        "nodes": {
            "192.168.4.10:1995": 1
        },
        "type": "roundrobin"
    }
}'
```

With this configuration, APISIX would only forward the request to the upstream service at `192.168.4.10:1995` if and only if the request is sent from `192.168.5.3`. See the next section to learn more about filtering options.

More examples can be found in [test cases](https://github.com/apache/apisix/blob/master/t/stream-node/sanity.t).

## More stream route filtering options

Currently there are three attributes in stream routes that can be used for filtering requests:

- `server_addr`: The address of the APISIX server that accepts the L4 stream connection.
- `server_port`: The port of the APISIX server that accepts the L4 stream connection.
- `remote_addr`: The address of client from which the request has been made.

Here is an example:

```shell
curl http://127.0.0.1:9180/apisix/admin/stream_routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
    "server_addr": "127.0.0.1",
    "server_port": 2000,
    "upstream": {
        "nodes": {
            "127.0.0.1:1995": 1
        },
        "type": "roundrobin"
    }
}'
```

It means APISIX will proxy the request to `127.0.0.1:1995` when the server address is `127.0.0.1` and the server port is equal to `2000`.

Here is an example with MySQL:

1. Put this config inside `config.yaml`

   ```yaml
   apisix:
     proxy_mode: http&stream  # enable both http and stream proxies
     stream_proxy: # TCP/UDP proxy
       tcp: # TCP proxy address list
         - 9100 # by default uses 0.0.0.0
         - "127.0.0.10:9101"
   ```

2. Now run a mysql docker container and expose port 3306 to the host

   ```shell
   $ docker run --name mysql -e MYSQL_ROOT_PASSWORD=toor -p 3306:3306 -d mysql mysqld --default-authentication-plugin=mysql_native_password
   # check it using a mysql client that it works
   $ mysql --host=127.0.0.1 --port=3306 -u root -p
   Enter password:
   Welcome to the MySQL monitor.  Commands end with ; or \g.
   Your MySQL connection id is 25
   ...
   mysql>
   ```

3. Now we are going to create a stream route with server filtering:

   ```shell
   curl http://127.0.0.1:9180/apisix/admin/stream_routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
   {
       "server_addr": "127.0.0.10",
       "server_port": 9101,
       "upstream": {
           "nodes": {
               "127.0.0.1:3306": 1
           },
           "type": "roundrobin"
       }
   }'
   ```

   It only forwards the request to the mysql upstream whenever a connection is received at APISIX server `127.0.0.10` and port `9101`. Let's test that behaviour:

4. Making a request to 9100 (stream proxy port enabled inside config.yaml), filter matching fails.

   ```shell
   $ mysql --host=127.0.0.1 --port=9100 -u root -p
   Enter password:
   ERROR 2013 (HY000): Lost connection to MySQL server at 'reading initial communication packet', system error: 2

   ```

   Instead making a request to the APISIX host and port where the filter matching succeeds:

   ```shell
   mysql --host=127.0.0.10 --port=9101 -u root -p
   Enter password:
   Welcome to the MySQL monitor.  Commands end with ; or \g.
   Your MySQL connection id is 26
   ...
   mysql>
   ```

Read [Admin API's Stream Route section](./admin-api.md#stream-route) for the complete options list.

## Accept TLS over TCP connection

APISIX can accept TLS over TCP connection.

First of all, we need to enable TLS for the TCP address:

```yaml
apisix:
  proxy_mode: http&stream  # enable both http and stream proxies
  stream_proxy: # TCP/UDP proxy
    tcp: # TCP proxy address list
      - addr: 9100
        tls: true
```

Second, we need to configure certificate for the given SNI.
See [Admin API's SSL section](./admin-api.md#ssl) for how to do.
mTLS is also supported, see [Protect Route](./mtls.md#protect-route) for how to do.

Third, we need to configure a stream route to match and proxy it to the upstream:

```shell
curl http://127.0.0.1:9180/apisix/admin/stream_routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
    "upstream": {
        "nodes": {
            "127.0.0.1:1995": 1
        },
        "type": "roundrobin"
    }
}'
```

When the connection is TLS over TCP, we can use the SNI to match a route, like:

```shell
curl http://127.0.0.1:9180/apisix/admin/stream_routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
    "sni": "a.test.com",
    "upstream": {
        "nodes": {
            "127.0.0.1:5991": 1
        },
        "type": "roundrobin"
    }
}'
```

In this case, a connection handshaked with SNI `a.test.com` will be proxied to `127.0.0.1:5991`.

## Proxy to TLS over TCP upstream

APISIX also supports proxying to TLS over TCP upstream.

```shell
curl http://127.0.0.1:9180/apisix/admin/stream_routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
    "upstream": {
        "scheme": "tls",
        "nodes": {
            "127.0.0.1:1995": 1
        },
        "type": "roundrobin"
    }
}'
```

By setting the `scheme` to `tls`, APISIX will do TLS handshake with the upstream.

When the client is also speaking TLS over TCP, the SNI from the client will pass through to the upstream. Otherwise, a dummy SNI `apisix_backend` will be used.