我正在尝试将httpd mod_proxy配置为Google Cloud Platform中的反向代理 . 我设置了一个TCP负载均衡器，并在VM apache配置中尝试了类似的功能 .
<Proxy "*">
</Proxy>
Listen 7001
Listen 7002
<VirtualHost *:7001>
ProxySourceAddress <LB IP 1 here>
</VirtualHost>
<VirtualHost *:7002>
ProxySourceAddress <LB IP 2 here>
</VirtualHost>
Apache日志显示我尝试通过代理获取到yandex.ru：
AH01114: HTTP: failed to make connection to backend: www.yandex.ru
(70007)The timeout specified has expired: AH00957: HTTP: attempt to connect to 5.255.255.5:80 (*) failed
httpd版本2.4.6 . OS Centos 7 .
我在这里错过了什么？