Comcast

Comcast simulates common network problems such as latency, bandwidth restrictions and dropped, reordered or corrupted packets. Distributed systems are often tested under hard failures like network partitions or instance termination, but they more often face these less catastrophic conditions.

Comcast is a thin wrapper around system tools: on Linux it uses iptables and tc, and on BSD-derived systems such as macOS it uses ipfw and pfctl. Network conditions are applied and removed with a single command, to observe how an application behaves on a degraded network.

Comcast is free and open source under the Apache 2.0 licence.