#> ipchains -A forward -s 192.168.1.1/255.255.255.0 -j MASQ
 하면 아래같은 에러메세지가 나오는데 ???
  warning: you must enable IP forwarding for packets to be
forwarded at all:
 use 'echo1 > /proc/sys/net/ipv4/ip-forward'
 어떻게 해야 할지요?