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Created December 16, 2025 20:23
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OpenSSH vs HPN-SSH Performance Comparison
The following image shows throughput rates of OpenSSH (the blue line) versus HPN-SSH. HPN-SSH
shows three different options. AES-GCM is the fastest cipher available. None is with encryption disabled
but still using the MAC cipher. NoneMac disables both ciphers. None and NoneMac are used here to
demonstrate the impact of ciphers on throughput.
The Y axis is throughput in Mpbs (0 to 8,000) and the X axis is the RTT of the path.
This graphs was generated by running multiple 40 GB transfers between two 10Gbps connected hosts
back to back. We used netem to artificially inject delay into this path to simulate different
RTTs. The median value of each set of runs was used to compute the values presented here.
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rapier1 commented Dec 16, 2025

HPNvsOpenSSH

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rapier1 commented Dec 16, 2025

The vertical blue line represents the RTT corresponding to a 128MB bandwidth delay product. This corresponds, roughly, to HPN-SSH seeing significant performance impact caused by delay.

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