No TCP socket for sport 42582 dport 1337

[oliverhu]

Describe your issue

• Is this a bug report or a feature request?
  bug report

• Describe the issue
  tap device doesn't respond

• What is the expected behaviour?
  should respond..

• How to reproduce the problem?

Command:
nmap -Pn 10.0.0.4 -p 1337

in level-ip log:
No TCP socket for sport 56996 dport 1337

in tcpdump:
tcpdump -i any host 10.0.0.4 -n

13:00:08.067870 ARP, Request who-has 10.0.0.4 tell 10.0.0.5, length 28
13:00:08.067909 ARP, Reply 10.0.0.4 is-at 00:0c:29:6d:50:25, length 28
13:00:08.219951 IP 10.0.0.5.56996 > 10.0.0.4.1337: Flags [S], seq 4159220327, win 1024, options [mss 1460], length 0
13:00:08.320111 IP 10.0.0.5.56997 > 10.0.0.4.1337: Flags [S], seq 4159285862, win 1024, options [mss 1460], length 0

Same issue happen when I try to use the curl application to request google.com, 10.0.0.4 doesn't respond. It does respond with ping tho:

$ ping -c3 10.0.0.4
PING 10.0.0.4 (10.0.0.4) 56(84) bytes of data.
64 bytes from 10.0.0.4: icmp_seq=1 ttl=64 time=0.054 ms
64 bytes from 10.0.0.4: icmp_seq=2 ttl=64 time=0.071 ms
64 bytes from 10.0.0.4: icmp_seq=3 ttl=64 time=0.065 ms

13:05:11.023961 IP 10.0.0.5 > 10.0.0.4: ICMP echo request, id 5001, seq 1, length 64
13:05:11.024002 IP 10.0.0.4 > 10.0.0.5: ICMP echo reply, id 5001, seq 1, length 64
13:05:12.039468 IP 10.0.0.5 > 10.0.0.4: ICMP echo request, id 5001, seq 2, length 64
13:05:12.039522 IP 10.0.0.4 > 10.0.0.5: ICMP echo reply, id 5001, seq 2, length 64
13:05:13.063461 IP 10.0.0.5 > 10.0.0.4: ICMP echo request, id 5001, seq 3, length 64
13:05:13.063506 IP 10.0.0.4 > 10.0.0.5: ICMP echo reply, id 5001, seq 3, length 64

Describe your running environment

This is important for troubleshooting. Please attach at least the following info:

• OS (e.g. cat /etc/os-release):
  NAME="Ubuntu"
  VERSION="19.10 (Eoan Ermine)"

• Kernel (e.g. uname -a):
  Linux pig 5.3.0-51-generic #44-Ubuntu SMP Wed Apr 22 21:09:44 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux