Wednesday, May 24, 2017

Google Cloud Print and Web Filters

At work, I have three LANTronix XPrintServer systems to make printers available to our chromebooks -- one for each school's printers. Recently, two schools' printers were listed as "Offline" and one wasn't. I eventually realized that my web filter was interfering with the keep-alive traffic between the devices and Google. The working system was already exempted in the web filter, so I added the other two and their printers became available almost immediately.

In the past, we would restart the devices and complain about how unstable GCP seemed to be. Now I'm starting to wonder if this might be the root cause of that apparent instability. If the filter blocked even one keep-alive signal, it would make sense that it would knock things offline indefinitely.

So if you use GCP and some kind of server to control it (Google Cloud Print Service, PaperCut, uniFLOW, XPrintServer, etc.) you might want to exempt its traffic from your web filtering.