Hello there,
I have an issue whereby WorldPay is complaining that they ran some sort of test against one of my websites, stating that it failed because:
“The host responded 4 times to 4 TCP SYN probes sent to destination port 24567 using source port 53. However, it did not respond at all to 4 TCP SYN probes sent to the same destination port using a random source port.”
For background, the host is actually behind Cloudflare, so they used the Cloudflare IP, but I wanted to try and test/reproduce this to confirm, so I could check to make sure it is in fact an issue, and if it is, then I will be able to run the test again to know that I fixed it. After googling around, I had believed that the following Linux command would allow me to test the sending of a SYN packet to a host on port 24567 from destination port 53 …
SERVER_IP=104.26.3.250
COUNT=1
DEST_PORT=24567
SOURCE_PORT=53
sudo hping3 --syn --baseport 53 --destport 24567 -c 1 104.26.3.250
…but I always get 100% packet loss as shown below:
Is my test incorrect? Is there some other command I should be running? Or is this just a blip on Worldpay’s side, which may or may not be related to the fact that they are using Cloudflare’s IP?
Any help/advice is appreciated.