My new Centso7 server that I am testing out is connected with a public address on my dmz. I am connected to the console port. Overnight the following message was logged to the console:

[44133.679108] conntrack: generic helper won't handle protocol 47. Please consider loading the specific helper module.

Protocol 47 is GRE. So was this 'just' an a ping by an attacker?

No one, but I have any business on this server. Well other than the files I put up for people.

thanks