[ 1200.226285][T10973] Could not find device with ifindex 2000 in netnsfd 11 [ 1200.227106][T10973] Could not find netns with fd: 2000 [ 1200.227819][T10973] Cannot link a netdevsim to itself [ 1200.228521][T10973] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).