ipfw: getsockopt(IP_FW_ADD): Invalid argument

[Ian Smith]

In freebsd-questions Digest, Vol 370, Issue 2, Message: 14
On Mon, 4 Jul 2011 09:11:07 -0700 (PDT) Unga <unga888 at yahoo.com> wrote:
 > --- On Mon, 7/4/11, Unga <unga888 at yahoo.com> wrote:
 > 
 > > From: Unga <unga888 at yahoo.com>
 > > Subject: ipfw: getsockopt(IP_FW_ADD): Invalid argument
 > > To: freebsd-questions at freebsd.org
 > > Date: Monday, July 4, 2011, 11:48 AM
 > > Hi all
 > > 
 > > Following ipfw rule develop error indicated in the subject
 > > line:
 > > ipfw add 100 fwd 127.0.0.1,1234 tcp from any to any 1234
 > > out via wlan0
 > > 
 > > What I want to do is forward any packet going to port 1234
 > > to 127.0.0.1:1234.
 > > 
 > > I have built the kernel with "options     
 > >    IPFIREWALL_FORWARD".
 > > 
 > > What's the error here? Is the rule incorrect?
 > > 
 > > This is FreeBSD 8.1.
 > > 
 > > Many thanks in advance.
 > > 
 > > Unga
 > > 
 > 
 > Does anybody successfully use the "ipfw fwd"? If so in which FreeBSD version?

Not I, but many do.  On the face of it the rule looks correct.  Do you 
have a TCP service running on localhost:1234 ?  Does wlan0 exist?  You 
may do better posting to the freebsd-ipfw list, with more information.

cheers, Ian