kernel: conntrack: generic helper won’t handle protocol 47.

I was getting the following message in my log files on my Debian firewall. kernel: conntrack: generic helper won’t handle protocol 47. Please consider loading the specific helper module. The nf_conntrack_proto_gre module needs to be loaded to resolve this. modprobe nf_conntrack_proto_gre To load it automatically at boot, I created a new file (gre.conf) in /etc/modules-load.d…