Simple reproducer:
sudo add-apt-repository cloud-archive:pike sudo apt update sudo apt install openvswitch-switch sudo ovs-vsctl add-br br-tun sudo ovs-vsctl add-port br-tun gre0 -- set interface gre0 type=gre options:remote_ip=10.100.1.1
this will cause ovs to create the gre_sys device in the kernel; the remote_ip can be anything but is obviously not functional.
Simple reproducer:
sudo add-apt-repository cloud-archive:pike remote_ ip=10.100. 1.1
sudo apt update
sudo apt install openvswitch-switch
sudo ovs-vsctl add-br br-tun
sudo ovs-vsctl add-port br-tun gre0 -- set interface gre0 type=gre options:
this will cause ovs to create the gre_sys device in the kernel; the remote_ip can be anything but is obviously not functional.