[ 1195.970776][T10981] Could not find device with ifindex 2000 in netnsfd 11 [ 1195.971529][T10981] Could not find netns with fd: 2000 [ 1195.972106][T10981] Cannot link a netdevsim to itself [ 1195.972758][T10981] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).