What is Error 17?

What is Error 17?
First, this is not an error that is impacting the functionality of our repeater system.
The error comes from the Echolink system. (Echolink, and IRLP, are systems that allow people to remotely access our repeater system). People that use Echolink are registered with Echolink and the IP address of that registration is databased. When a know registrant accesses our Echolink server, they are let in without issue. If an unknown IP address attempts to access our Echolink server, Error 17.

When we have checked the Echolink logs to see what the offending IP addresses were, and who they belonged to, it was found to be most often the NSA or Homeland Security.