One of my friends was having an issue passing specific traffic on a network he was using and came to me for assistance (all web traffic was allowed, but certain ports were blocked to specific hosts). I couldn’t duplicate the problem on my home network so we went over the various options that were successful in passing the traffic as desired. Connecting via an Open Wireless network in the area allows him to bypass the issue entirely. Being that this was non-sensitive information, this could provide the path to creating a happy environment for his applications. I’m being purposefully vague here. The gist is that while connected to one network he couldn’t access non-standard port services, but while on the open wifi connection he was unable to access LAN services. He wants to be able to access both at the same time, and doesn’t want to bother the firewall administrator every time there’s a new port change he needs to make to continue using the corporate network.
We first attempted a metric change to the wireless adapter to have higher priority, thinking that it would fall back to the wired interface for anything inaccessible by the wireless adapter (similar to a load balancer – of sorts). That didn’t work as I expected so we were back to square one.
The solution I am cooking up is an attempt to remedy that. [Read more…]