Does PFSense modify TCP window sizes?

  • Dear experts,

    I'm working to improve speeds over a high latency network between our east and west coast offices. On the clients, I'm experimenting with larger tcp window sizes over our site-to-site OpenVPN connection, and also direct between our public IPs. PFsense boxes serve as our border router, nat, and openvpn servers at both sites.

    My question is: does PFSense modify the tcp windows sizes? There is a system tunable about tcp window sizes, but I'm wondering if that is just for the system itself, and not the packets being routed through the system.

    Thanks much!


  • TCP window size is a parameter at a higher layer that end-systems use to work out how much data to have outstanding in the pipeline before waiting/expecting ACKs to have come back. I played with this many years ago tuning continuous flows of a data acquisition process across a long link. TCP window size needs to be adjusted on the end-systems.

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