In most firewall setups, the TCP connection will be torn down by the firewall if it is idle to conserve resources. The idle timeout is probably not something you can control. Some will tear them down if they are idle and a resource limit is being hit.
Most corp environments won't allow any machines to make an outbound TCP connection anyway.
Also, using this mechanism means you are going to have scaling problems. I think more reliable solution is to queue up information and have your clients poll for them regularly. Utilize caching if possible such that a subsequent client poll will get the cached data from the customers proxy cache, if they are using one.
If you have to push data in a timely manner, in sub-second land (i.e. financial services), then consider some messaging infrastructure such an NServiceBus distributor on client side, but that will require a customer install...
So have you tried using Toredo? Having read that it would appear there it is prob too complicated for a user to setup.
