HelenOS sources

IP_PROTO_TCP      178 uspace/srv/net/tcp/inet.c 	rc = inet_init(IP_PROTO_TCP, &tcp_inet_ev_ops);
IP_PROTO_TCP      165 uspace/srv/net/tcp/pdu.c 		phdr->protocol = IP_PROTO_TCP;
IP_PROTO_TCP      175 uspace/srv/net/tcp/pdu.c 		phdr6->next = IP_PROTO_TCP;