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I am using iperf to measure my uplink speed between my home PC behind NAT and a fully accessible root server. It does so using a TCP connection. For whatever reason it seems that iperf can only measure client to server speed, where client is the one starting the TCP connection and server is the listening part.

Unfortunately my PC is behind NAT and the TCP connection can only be initiated in this direction.

Is there another tool that does this but uses the TCP connection in both directions?

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up vote 3 down vote accepted

I just had the same question and found a patch that seemed to work (after some extra futzing). You can checkout the patched iperf code here:

If you're using Linux, building should be as easy as ./configure && make; the executable will be at src/iperf. Just add the --reverse flag to both the client and server instantiations, per the README.

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