What tools are available to simulate certain network conditions on Ubuntu?

Question

In order to test our deployment I want to simulate certain network events like connection losses, timeout, limited bandwidths etc.

I already googled for this but haven't found something that really suited my needs. ipfw seems to be what I need but I can't seem to find an ipfw package for Ubuntu. Also I'd like to know whether there are alternatives or even better tools for my task.

Answer 1

You can simulate those things with firewall.

Userland tool to modify firewall rules is called iptables

for example if you want to simulate 5 seconds of connection loss you can do this

iptables -I INPUT -p tcp -s source.ip.for.which.you.want.to.appear.to.timeout --dpor $port -j DROP ; sleep 5; iptables -D INPUT -p tcp -s source.ip.for.which.you.want.to.appear.to.timeout --dpor $port -j DROP ;

Answer 2

iptables is great, but some tools are sharper when dealing with this kind of problems.

• Lagfactory (based on netem)
• nistnet. Old but powerful.
• dummynet

And also wanem, not a standalone app but more a customized router distro.

Answer 3

From the sister site Stack Overflow: Simulate delayed and dropped packets on Linux