vyos@vyos:~$ monitor traffic interface eth1 numeric filter 'port 80' | match '1.1.1.1'
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), snapshot length 262144 bytes

^C9 packets captured
19 packets received by filter
0 packets dropped by kernel
Traceback (most recent call last):
  File "/usr/libexec/vyos/op_mode/tcpdump.py", line 169, in <module>
    call(f'{command} -i {ifname}')
  File "/usr/lib/python3/dist-packages/vyos/utils/process.py", line 187, in call
    out, code = popen(
                ^^^^^^
  File "/usr/lib/python3/dist-packages/vyos/utils/process.py", line 82, in popen
    pipe = p.communicate(input, timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/subprocess.py", line 1199, in communicate
    self.wait()
  File "/usr/lib/python3.11/subprocess.py", line 1262, in wait
    return self._wait(timeout=timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/subprocess.py", line 1997, in _wait
    (pid, sts) = self._try_wait(0)
                 ^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/subprocess.py", line 1955, in _try_wait
    (pid, sts) = os.waitpid(self.pid, wait_flags)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyboardInterrupt

vyos@vyos:~$