The problem I encountered here is weird. There are two ubuntu linux machines, two identical HTTP servers run on them. One is ok on port forwarding, the other gets ERR_EMPTY_RESPONSE.
I've checked ufw settings but found nothing, since I can do SSH login on any of them, it should be enough for port forwarding. So, any suggestion to debugging this problem? Thank you in advance.
FYI, I did the test: On the server, Port forwarding is 64444:localhost:64444.
# nc -vv -l 64444 // Got nothing.
On the client, run:
# nc -vv localhost 64444
myhost [127.0.0.1] 64444 (?) open
sent 0, rcvd 0: NOTSOCK
# nc -vv localhost 64441 // any other port
myhost [127.0.0.1] 64441 (?): connection refused
sent 0, rcvd 0: NOTSOCK