[ 1078.051430][T11100] Could not find device with ifindex 2000 in netnsfd 11 [ 1078.052395][T11100] Could not find netns with fd: 2000 [ 1078.053435][T11100] Cannot link a netdevsim to itself [ 1078.054432][T11100] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).