[ 849.379429][T10200] Could not find device with ifindex 2000 in netnsfd 11 [ 849.380087][T10200] Could not find netns with fd: 2000 [ 849.380596][T10200] netdevsim netdevsim453 eth0: Cannot link a netdevsim to itself [ 849.381313][T10200] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).