[ 1226.707691][T11129] Could not find device with ifindex 2000 in netnsfd 11 [ 1226.708416][T11129] Could not find netns with fd: 2000 [ 1226.708954][T11129] Cannot link a netdevsim to itself [ 1226.709935][T11129] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).