Tonight, I arrived home hoping to jump right in to my “moonlighting” gig only to discover that an issue with my computer from this morning had persisted. For some reason, something, some application was causing a consistent amount of traffic (not large amounts of it mind you) across my local Ethernet connection. Fortunately for me, I am somewhat tech savvy and thus commenced troubleshooting to discover the source rogue application.
First off, sniff the TCP/UDP traffic
After launching TCP Viewer and letting it do its thing for a few seconds, I noticed that there was a group of three or so applications connecting and disconnecting in sequence, port scanning out my machine to my router on destination port 5678. Lo and behold, it ended up being the svchost.exe application. Not just one or two ports, but scanning tens if not hundreds if left to do its thing.
Next, Find the Application and Kill It
I launched Process Explorer to try to figure out if svchost.exe was truly the offending thread. I then isolated the application with the same PID as the one reported in TCP Viewer (in my case 1324). Yep, svchost.exe. Right-click | Kill Application. Bye-bye. No more solid blinking lights across my gigabit Ethernet connection!
Now you ask, what service or application would be sending and receiving such a high rate of packets (ultimately crashing my router due to the amount of hits it was getting)? Well, it turns out that the UPnP services (which I had assumed I had disabled) were for some reason hanging on the requests to my router. All requests were headed to the router’s internal interface (10.0.0.1) on port 5678. From what I can tell, the router was either dropping the packets or not responding properly so the SSDP Discover Service was scanning out ports to try to “do its thing”.
Launch the local service manager, stop, and then finally DISABLE the following services:
- Universal Plug and Play Device Host
- SSDP Discovery Service
I do not plan on going in to detail on what these services do, but suffice it to say, they are unnecessary and in this case, a pain in the behind. There are a bunch of other article on this topic, but there did not appear to be one detailing this exact scenario, so hopefully this helps someone else from having to spend hours troubleshooting.