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Configure the TCP Window Size in a System File

You can configure the TCP window size using the sysctl.conf system file.

You can edit the system file on the Web Gateway interface.

  1. Select Configuration | File Editor.
  2. On the files tree, navigate to the branch for the appliance where you want to configure the TCP window size, then select sysctl.conf.
  3. In the editing area on the right, type parameter names and values for the TCP window size.
    Type these entries after this line:


    Otherwise the parameter values will be overridden by those configured under Configuration | Appliances as part of the proxy system settings.
    • net.core.rmem_max = <maximum size in KB> — Sets the maximum size of the TCP window, specified as a number (without KB).

      This size is the absolute limit. If a larger size is configured using a different method, it is only effective up to the number of bytes configured here.

      Alternatively, you can set the maximum size using this parameter: net.ipv4.tcp.rmem_max =
      <maximum size in KB>. This size cannot be exceeded either by using any other configuration method.

      If both parameters are entered in the system file, net.core.rmem_max takes precedence.
    • net.ipv4.tcp.rmem_min = <minimum size in KB> — Sets the minimum size of the TCP window, specified as a number (without KB).

      If you configure a value greater than 65535 here, window scaling cannot be disabled by any other setting on Web Gateway.
  4. Click Save Changes.
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