ICMP_EXC_TTL 127 net/ipv4/ip_forward.c icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0); ICMP_EXC_TTL 420 net/ipv4/ip_gre.c if (code != ICMP_EXC_TTL) ICMP_EXC_TTL 313 net/ipv4/ipip.c if (code != ICMP_EXC_TTL) ICMP_EXC_TTL 440 net/ipv6/sit.c if (code != ICMP_EXC_TTL)