I've seen people use the exclamation mark (!) in multiple examples, but when I try to use it I get an error.

The rule I'm trying:

-A OUTPUT -m owner --gid-owner 1006 -d ! -j DROP

The error:

Bad argument ''

What is the correct syntax for this?

1 Answer 1


Just as the manpage states:

[!] -d, --destination address[/mask][,...]
       Destination  specification.   See  the  description  of  the  -s
       (source)  flag  for  a  detailed description of the syntax.  The
       flag --dst is an alias for this option.

That makes it

! -d
  • 5
    It has nothing to do with shady blogs, the syntax has changed for iptables and the exclamation mark went before the flag at some point.
    – Martin
    Jan 2, 2013 at 13:27
  • You can also use it like: ! -d <URL>.
    – another
    Nov 19, 2019 at 13:39

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