[ 1183.530078][T10983] Could not find device with ifindex 2000 in netnsfd 11 [ 1183.531272][T10983] Could not find netns with fd: 2000 [ 1183.532207][T10983] Cannot link a netdevsim to itself [ 1183.533314][T10983] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).