# MacOS is able to limit bandwith form specific protocol or source-ip on the fly. Creating an bandwidth limtation rule won't break your download #Build a pipe with a limited bandwidth (example 1Mbits/s) sudo ipfw pipe 1 config bw 1Mbit/s #Assign a rule to redirect the protocol on that pipe (for example http from www.example.com) sudo ipfw add 1 pipe 1 proto tcp src-port 80 src-ip www.example.com #You can show your pipe like that sudo ipfw pipe show #Delete the created pipe with that both comands # delete the redirection rule : sudo ipfw del 1 # delete the pipe : sudo ipfw pipe 1 delete