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Using two different Windows laptops, one with Win 7 and the other Win 11, I'm trying to connect to the HTTP GUI of a device (cell phone booster) that's connected directly to my laptop through an ethernet cable, but when I try to connect I get "ERR_CONNECTION_REFUSED". I can successfully ping the address of the device, but trying to connect to port 80 fails to establish a full 3-way handshake. A Wireshark trace (below) shows that the TCP 3-way handshake between the laptops and HTTP server is never established. If you follow the trace, you can see that the client (windows laptop) sends the SYN with, and the HTTP server ACKs with the correct sequence number, but the client keeps doing a retransmission of the same SYN segment as though the ACK is never getting to the client.

Here are some symptoms and troubleshooting methods I tried...

  • I'm trying with Chrome, Edge, and IE browsers, no difference.

  • Tried connecting to the HTTP server with netcat, but saw the same error and TCP failure.

  • I use my Kali machine and it connects fine, so I know the HTTP server is working.

  • I've turned off the Windows firewalls on both laptops, but that doesn't help.

  • I can connect to the internet with out problems.

  • Enables IIS on one Windows laptop and set the IP address to the identical address as the HTTP server, and connected the laptops directly together with an ethernet cable. I successful was able to connect to the IIS HTTP server.

I appreciate if anyone has any advice.

Thanks

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  • The fact that the TCP "RST" (reset) bit is set in the replies from the device means the device is resetting/refusing the connection. Did you set up the device to only speak to your Linux box's MAC or IP address? Does the device have some limitation of only talking to one device at a time? Ot maybe it's choking on a TCP option that Windows sets but Linux doesn't? (that seems unlikely)
    – Spiff
    Commented Oct 10, 2023 at 6:01
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    @Spiff This is a recent issue. I've always talked to these devices with these same Windows boxes. I thought the problem might have been a Windows update, but now I'm wondering if it was a firmware update to the devices. I guess my next step, I should compare the TCP headers of the SYN segments from the Windows machine and the Linux machines and see which options are set differently.
    – Frank
    Commented Oct 10, 2023 at 16:30

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Reset to default

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