[ 1210.653115][T11123] Could not find device with ifindex 2000 in netnsfd 11 [ 1210.654187][T11123] Could not find netns with fd: 2000 [ 1210.655289][T11123] Cannot link a netdevsim to itself [ 1210.656409][T11123] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).