For testing purposes, to determine how a protocol implementation behaves in the presence of packet loss, I would like to force packet loss on one of my network devices. Specifically, I would like to be able to tune the packet loss anywhere between 0% and 100%. I have a little experience with iptables and it seems to me I should be able to achieve it using that, but I haven't been able to. Achieving 100% packet loss is not a problem though ;). Any ideas on how to do this?
Look into iptables' statistic module.
I guess something like
iptables -A FORWARD -m statistic --mode random --probability 0.5 -j DROP
should do the trick on a router.