CommunityManager can be set up to use a proxy server to make external connections, such as to third party RSS feed's via the web.config.
To do this - please enter the following into the web.config file in the root of the website under the tag
<system.net>
<defaultProxy>
<proxy proxyaddress ="http://ip_address:port" bypassonlocal="True" usesystemdefault="False" />
</defaultProxy>
<system.net>
Replace ip_address with the IP address of your proxy. I.e. 192.168.0.1
Replace port witht he port number of your proxy. I.e. 3128
Save the web.config file and give it a try. To confirm it is working, you may wish to monitor your proxy server's log(s) to confirm the request is going via the proxy. You should see a request via the primary IP address of your web server.
Please note that any changes to the web.config file will cause the ASP.NET application to recompile, and any current sessions on your site will be reset and users will need to re-log into your site.