1

When I launch an FTP transfer from a client machine, it fails because it cannot connect to the server. With tcpdump I can see that the client sends a SYN to the server, and I can also see that the server received the SYN but it does not respond.

Wireshark screenshot

I made sure that the source/destination MAC address is correct, same for IP address.

There is absolutely no firewall rules whatsoever.

Any ideas how I can debug the issue?

5
  • @PeterZhabin There isn't enough information to know whether it really is the same issue. There is a lot of other possible reasons, some of which are probably more likely. However it doesn't hurt trying the suggestions in the older question to see if they make a difference.
    – kasperd
    Oct 10, 2018 at 21:36
  • 2
    I already checked that question, it did not work for me. However I was able to solve my problem, in fact the client was behind a VLAN that was corumping the TCP checksum, doing ethtool -K ethX rx off tx off did the trick. I don't know what to do with the question, you decide. Oct 11, 2018 at 21:32
  • 1
    I think the right thing to do with the question in this case is to flag it for moderator attention explaining why it was erroneously closed as a duplicate of an unrelated question. And once it has been reopened post your own answer explaining how you fixed the problem and accept your own answer.
    – kasperd
    Oct 11, 2018 at 22:24
  • I would suggest posting your answer on the linked duplicate question. Your question seems to be virtually identical, so other people who search for this problem will find your solution more easily there. Oct 16, 2018 at 19:32
  • just did that, thx. Oct 16, 2018 at 20:37

0

Browse other questions tagged .