公司内网通过正向代理访问阿里云kafka，报could not be established. Broker may not be available

场景：公司内网应用通过DMZ部署的正向代理，访问阿里云kafka（公网），报：

could not be established. Broker may not be available。

配置相关：

DMZ：172.11.7.268, 172.11.7.269, 172.11.7.270

阿里云kafka:

• 118.178.39.26
• 114.55.131.86
• 118.178.214.174

内网应用：10.18.123.14

相关描述

在DMZ三台机器开启正向代理（用socat）：

/apps/svr/socat1.7/bin/socat TCP-LISTEN:9093,fork,reuseaddr TCP:118.178.39.26:9093

/apps/svr/socat1.7/bin/socat TCP-LISTEN:9093,fork,reuseaddr TCP:114.55.131.86:9093

/apps/svr/socat1.7/bin/socat TCP-LISTEN:9093,fork,reuseaddr TCP:118.178.214.174:9093

在内网应用配置的主机名映射如下：

172.11.7.268  mvxl59355
172.11.7.169  mvxl65938
172.11.7.170 mvxl59356
118.178.39.26 mvxl59355
118.178.214.174 mvxl65938
114.55.131.86 mvxl59356

报错信息如下：

2021-07-11 08:03:51.093][WARN][{kafka-producer-network-thread | producer-1}][TID: N/A][o.a.k.c.NetworkClient#processDisconnection 748]LINECONTENT:[Producer clientId=producer-1] Connection to node -1 (mvxl59355/118.178.39.26:9093) could not be established. Broker may not be available.

Failed to send; nested exception is org.apache.kafka.common.errors.TimeoutException: Topic it_trace_to_aliyun not present in metadata after 30000 ms