[ 1196.790591][T10967] Could not find device with ifindex 2000 in netnsfd 11 [ 1196.791323][T10967] Could not find netns with fd: 2000 [ 1196.791900][T10967] Cannot link a netdevsim to itself [ 1196.792831][T10967] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).