This is a configurable TCP/UDP packet impairment tool for Linux. It looks like this:

Install the dependencies, including the Linux nfqueue library:

sudo apt-get install libnetfilter-queue-dev
sudo python setup.py develop

To get realistic network simulation on the loopback device, you probably want to set the MTU to something small:

ip link show dev lo  # show current MTU
sudo ip link set dev lo mtu 2048

For example, to impair TCP traffic on loopback port 3000:

sudo scripts/impaired_network_server -p 3000

It can also run as a UDP proxy, without root, if you specify a proxy port:

scripts/impaired_network_server -l user -t udp -p 3000 -x 3001

To see all of the options:

scripts/impaired_network_server --help

Packet Queue will clean up its iptables rules on shutdown. If it ever doesn't shut down gracefully, you can clear the rules like this:

sudo scripts/impaired_network_clear_iptables

You can run most of the tests like this:

python -m unittest discover tests  # run all tests in the tests/ directory

Some of the end-to-end tests will be skipped with the above command because they require root:

sudo python tests/test_e2e.py