[ 498.556872] Could not find device with ifindex 2000 in netnsfd 11 [ 498.557026] Could not find netns with fd: 2000 [ 498.557112] Cannot link a netdevsim to itself [ 498.557209] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).