On Wed, 3 Jul 2002, Wei Koong CHAI wrote: > My questions: > > [1] In the struct ipq_packet_msg, the data_len field is referring to what? > Is it referring to the length of the whole IP packet (header + payload) or > just the header or the payload alone?
The whole IP packet, which is the packet message payload. > And, is the payload[0] referring to > the first byte of the IP packet? Yes. Please refer to ipq_get_packet(3). > > [2] I have already managed to randomly decide a bit to corrupt within a > packet (which is just inverting the bit) but i'm unsure on how to actually > access the packet (header + payload) and invert the bit. An example of packet modification is at: http://cvs.netfilter.org/cgi-bin/cvsweb/netfilter/OLD/tools/ipq_client.c It won't compile anymore, but is trivial to fix. > > [3] I have read somewhere that the kernel would silently / automatically > drop the packet if i change the packet without updating the checksum. What > i need to know is that, which kernel will drop the packet? My bridge or the > receiving workstation? I don't want my libipq program to drop it as i need > it to be as transparent as possible. Generally, the receiving workstation. I'm sure I've seen the sending kernel drop invalid packets, but can't see (with a brief look) where this would happen in the current kernel. - James -- James Morris <[EMAIL PROTECTED]>
