I have questions about the linux kernel and IPsec at the layer 3, the files 'net/ipv4/ipip.c' and 'net/ipv4/tunnel4.c': Are these files necessary to implement IPsec? What are their main functionalities? I see many input and output files at net/ipv4 like: ip_input.c/ip_output.c or xfrm4_input.c/xfrm4_output.c, If IPsec is enabled, does the second group 'xfrm4_input.c/xfrm4_output.c' is used instead of the first one? Or the second ones are called by the first couple of functions? net/ipv4/ah4.c and net/ipv4/esp4.c also have input/output functions, when and how they are called? I am looking for a simple flow of network traffic in case of IPsec... I did not get my answer in the Linux kernel books, please answer me with your own technical knowledge. thank you. What is the flow of (input/output) information inside the layer 3 when IPsec is enabled? How IPsec is enabled at user space, is it done by setkey or socket system call with special arguments? ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ - To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs