About the using of libnetfilter_queue!

Hi,

I have some questions about the using of libnetfilter_queue. I use the RHEL 5.2 to develop my application (Kernel: 2.6.18-92.el5). I found that there are several strange phenomena when using the API of the libnetfilter_queue.

1. The nfq_get_timestamp() always returns the same value of the timestamp for all packets retrieved from the NFQUEUE. What is the cause of this problem?

2. I cannot set the maximum length of the queue by using the function nfq_set_queue_maxlen(). This function always returns -1 even though I have inputted the correct parameters into this function. I have searched about this issue in Google and someone said that kernel >= 2.6.20 would be supported to use this function. Is it true? If so, how can I set the maximum length of the queue when I use the kernel = 2.6.18?

Thank you very much!

Regards,

Jacky Luk