Overview of kernel network code (2)

sys/netinet/: IP(v4) networking
ip_{input, output}.c: IPv4 input and output
ip_icmp.c: ICMP(v4) operation
tcp_XXX.c: TCP operation
udp_usrreq.c: UDP operation
Some *BSDs share tcp/udp related files for both IPv4 and IPv6.
if_ether.c: IPv4 specific ethernet operation (e.g. ARP)
sys/netinet6/: IPv6 networking (KAME specific)
ip6_{input, output, forward}.c: IPv6 input, output, and forward
icmp6.c: ICMPv6 operation
tcp6_XXX.c: IPv6 specific TCP operation
udp6_usrreq.c: IPv6 specific UDP operation
Some *BSDs do not have tcp6/udp6 files
nd6_XXX.c: IPv6 Neighbor Discovery