i find lartc docs at lartc.org. There is only how to set ipsec. But i did not find documents about the implementation of native ipsec in 2.5.xx. If i want to see how to implement native ipsec , where can i start from? Especially i wish i can get some docs about it? Can anybody help me? yuan - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html