Hi all, Sorry about sending the question to both lists cause I am not sure which one is the best list. I am using the latest libnetfilter_queue and other dependencies (downloaded a couple of days ago). I've spent some time trying to rewrite the packets (specifically, the source IP address or the destination IP address) and reinject it back to the network. I think I got the code right. However, after I did the modification on the packets, although with the correct checksum at both IP and TCP layer (I have tried several fixed packet headers where the checksum is known beforehand and make sure checksum is computed correctly), the packet was not successfully reinjected (not captured by tcpdump). The weird thing is that they fail deterministically but randomly (to me) for different IP addresses. For example, if I rewrite the destination IP to 1.1.1.1, it succeeded, but if I rewrite the destination IP to 1.1.1.2, it then failed. And for source IPs, it always fails. I've tested the other fields like TTL or source port and destination port, it always succeeded. One possibility that can partially explain this is that my machine is not allowing spoofed IP address. But then I use hping to spoof other IPs and the packets are indeed captured by tcpdump (I also checked my iptables configuration). I then think if hping is using a different mechanism to send out packets than libnetfilter_queue. But I couldn't find the answer until I dive into the corresponding kernel module (I think hping is just using raw socket). I am wondering if there's a way to get the result of the injected packet (whether or not it is delivered out). I don't know what the return value of nfq_set_verdict() means, it is always some value larger than 0 (e.g. 32, 72 ...). Can anybody shed some lights on this? Thanks a lot! I can post my code here if needed. Regards. -Zhiyun -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
