taglinefilesource code
ip_forward247drivers/net/tunnel.cif(ip_forward(skb2, dev, 0, iph->daddr, 0))
ip_forward91include/net/ip.hextern int    ip_forward(struct sk_buff *skb, struct device *dev, int is_frag, unsigned long target_addr, int target_strict);           
ip_forward1522net/ipv4/ip.cif(ip_forward(skb, dev, is_frag|4, iph->daddr, 0))
ip_forward1680net/ipv4/ip.cif(ip_forward(skb, dev, is_frag, target_addr, target_strict))
ip_forward59net/ipv4/ipip.cif(ip_forward(skb, dev, 0, daddr, 0))