HI, I recommend using libipq, cause I am using it at the moment and it seems to perform pretty OK, interms of processing time and the like. A simple way of doing this (not necessarily the best) will be (roughly): -set rules to queue the concerned packets; -Create some kind of queue (just use stl deque, for example, or use priority queue) and put the packet_id, and the time it should be let go (ie current time + the amount of time you want to delay it) of each packet that is queued. (using libip methods, ipq_read, ipq_getpacket and the like, which are described pretty well in the man pages) -Create a thread that constantly checks the firing times of the top of the queue, and if it has passed, will simply call ipq_setverdict with the packet_id of the concerned packet, and remove the entry from the queue, and so on ... Regards, Oumer Quoting Joe Clark <joeclark@xxxxxxxxxxx>: > Hi. For a research project, I need to find a way to simulate long > delays (ie, > simulating 70ms or so of delay over a typically-1ms delay LAN). From > what I've > seen online, the Netfilter mechanism seems to be the best way to do > this. There > are some Linux packet filtering facilities available with little or no > work > (qdisc, tc, etc), but none seem to do the delay that I'm seeking. > > So, from my web search, I would need to write a simple kernel module > that would > NF_QUEUE all outgoing packets on a link, and then in user space read the > packet > info in, set up a delay-based queuing mechanism, and then dequeue the > packets > after the delay and reinject them (NF_ACCEPT via an ioctl?). > > Is that the best method? I saw something about libipq, which has to do > with how > to use the NF_QUEUE framework in userspace. I also saw a reference that > said I > could create a /dev/... device for reading in netfilter queued packets. > Which > is the preferred or current way to do it? > > Thanks for any help you can provide. > - Joe Clark > > > >
