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

Debian iptables Linux

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

This file just needs the single line: nf_conntrack_proto_gre