SYS_OUT
ctrl_file = SYS_OUT("./xdp_synproxy --iface tmp1 --ports 8080 \
ctrl_file = SYS_OUT("tc filter show dev tmp1 ingress");
ctrl_file = SYS_OUT("./xdp_synproxy --iface tmp1 --single");
ctrl_file = SYS_OUT("./xdp_synproxy --prog %s --single",