ipforward (разница есть или нет)

> sysctl -w net.ipv4.ip_forward=1
По-моему, это правильнее! ;-)

Хотя у меня в rc.ip_forward написано примерно так:

# Start IP packet forwarding:
ip_forward_start() {
  if [ -f /proc/sys/net/ipv4/ip_forward ]; then
    echo "Activating IPv4 packet forwarding."
    echo 1 > /proc/sys/net/ipv4/ip_forward
  fi
  # When using IPv4 packet forwarding, you will also get the
  # rp_filter, which automatically rejects incoming packets if the
  # routing table entry for their source address doesn't match the
  # network interface they're arriving on.  This has security
  # advantages because it prevents the so-called IP spoofing,
  # however it can pose problems if you use asymmetric routing
  # (packets from you to a host take a different path than packets
  # from that host to you) or if you operate a non-routing host
  # which has several IP addresses on different interfaces.  To
  # turn rp_filter off, uncomment the lines below:
  #if [ -r /proc/sys/net/ipv4/conf/all/rp_filter ]; then
  #  echo "Disabling rp_filter."
  #  echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter
  #fi
}