# AMQPConnectionError：连接到 rabbitmq-host:5672 被拒绝（111）

- **ID:** `communication/rabbitmq-connection-refused-ec2`
- **领域:** communication
- **类别:** network_error
- **错误码:** `111`
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

AMQP 客户端无法与 RabbitMQ 服务器建立 TCP 连接，因为服务器未在指定端口上监听、服务已关闭，或防火墙/安全组阻止了入站流量。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| RabbitMQ 3.12 | active | — | — |
| Erlang 26 | active | — | — |
| Pika 1.3 | active | — | — |
| amqp-node 0.10 | active | — | — |

## 解决方案

1. ```
   Check if RabbitMQ is running: `systemctl status rabbitmq-server` or `rabbitmqctl status`. If not running, start it: `systemctl start rabbitmq-server`.
   ```
2. ```
   Verify firewall rules: on Linux, run `sudo ufw status` or `iptables -L -n | grep 5672`. Ensure inbound TCP on port 5672 is allowed. For cloud providers, check security group inbound rules for the instance.
   ```
3. ```
   If RabbitMQ is listening on a different interface (e.g., localhost only), update the config file `/etc/rabbitmq/rabbitmq.conf` to bind to `0.0.0.0` or the correct IP: `listeners.tcp.default = 0.0.0.0:5672`. Restart RabbitMQ after changes.
   ```

## 无效尝试

- **Change the RabbitMQ username and password in the client** — Changing the RabbitMQ user credentials does not fix the connection refusal because the TCP handshake fails before any authentication occurs. (90% 失败率)
- **Increase the AMQP connection timeout to 60 seconds** — Increasing the connection timeout does not help because the error is immediate (connection refused), not a timeout. (95% 失败率)
- **Enable TLS/SSL on the AMQP client connection** — Enabling TLS on the client without configuring the server to accept TLS on the same port will still result in connection refusal or a different error. (85% 失败率)