unable to call ntohs function in kernel module

hello,
What i observed about noths with respect to Fedora core 1 kernel is that if i write a simple network C program i can call ntohl, ntohs,htonl,htons from netinet/in.h but same if i call from kernel module why it gives ntohs unresolved symbol error?
Also if try to include netinet/in.h it will give me errors at compile time.

regards,
parag.