How to listen all interfaces on FreeBSD with tcpdump

> tcpdump -i any
tcpdump: any: No such device exists
(BIOCSETIF failed: Device not configured)

(I would like to listen ICMP)

  • 3
    any is a linux specific construct... Mar 17 '18 at 23:23
  • try to run without -i. Mar 18 '18 at 0:04
  • @RuiFRibeiro what is correct under FreeBSD?
    – Dims
    Mar 18 '18 at 9:40
  • @YurijGoncharuk tcpdump any icmp doesn't work
    – Dims
    Mar 18 '18 at 9:41
  • 2
    As @RuiFRibeiro already stated, "any" is a Linux only option and doesn't work anywhere else. Read the man page.
    – Rob
    Mar 18 '18 at 10:55

I'm looking at this on FreeBSD 11.3 and there doesn't appear to be any way to do an "any". I thought multiple -is might work, despite the manpage's silence on it, but it only takes the first one. If tcpdump gets enhanced to support multiple -is then this ought to do it (or you can prove that it doesn't on your system):

tcpdump --list-interfaces | grep Running | cut -f 1 -d ' ' | cut -f 2- -d '.' | awk '{ print "-i " $1 }' | xargs -t -Jinterfaces tcpdump interfaces host

From the tcpdump man page:

An interface argument of "all" or "pktap,all" can be used to capture packets from all interfaces, including loopback and tunnel interfaces.

Therefore you can simply do, for example:

tcpdump -i all tcp port 80

If you don't specify the -i flag, then a set of all interfaces are again included in a pseudo interface that by default excludes loopback and tunnel interfaces. Again from the tcpdump man page:

On Darwin systems version 13 or later, when the interface is unspecified, tcpdump will use a pseudo interface to capture packets on a set of interfaces determined by the kernel (excludes by default loopback and tunnel interfaces).


I can't vouch for how well this method would serve any particular use case, but the brute force way to do this in FreeBSD would be to run N instances of tcpdump, one for each of the N interfaces known to ifconfig. You might run them as a grouped and backgrounded command, sending their combined output to a single file. It seems inevitable that the output file will have numerous duplicated packets, such as showing a packet when it arrives on interface a and then showing it again when it departs on interface b.

But if you really have to do it that way, consider:

    for i in $(ifconfig -l)
        ( tcpdump -i $i & )
} > tcpdump.out

As with anything in FreeBSD: Reading the manpage usually explains everything.

       -i interface
      Listen on interface.  If unspecified, tcpdump searches the  sys-
      tem interface list for the lowest numbered, configured up inter-
      face (excluding loopback), which may turn out to be,  for  exam-
      ple, ``eth0''.

      On  Linux  systems with 2.2 or later kernels, an interface argu-
      ment of ``any'' can be used to capture packets from  all  inter-
      faces.   Note  that  captures  on the ``any'' device will not be
      done in promiscuous mode.

      If the -D flag is supported, an interface number as  printed  by
      that flag can be used as the interface argument, if no interface
      on the system has that number as a name.


  • 2
    "On Linux systems"?
    – Dims
    Sep 19 '20 at 8:44

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