ipfw dscp support

[Ian Smith]

On Tue, 6 Dec 2011, alan yang wrote:
 > Hi Sergey,
 > 
 > I found from FreeBSD forum dated Aug. 2009 with the following:
 > 
 > vlad2005

Insufficient information to locate a forum post.  URL, please?

 > ...
 > Anyway, testing with improvement from patch, give desired result.
 > Code:
 > ipfw add 20 count ip from any to any dscp AF11
 > Show command from ipfw look ok.
 > Code:
 > freebsd# ipfw show
 > 00010  959 82291 modip dscp:AF11 ip from any to any
 > 00020   24  1584 count ip from any to any dscp AF11
 > 65535 1099 92987 allow ip from any to any

The PR you pointed to (kern/102471) includes some description, update to 
ipfw(8) and some references.  It doesn't mention any 'modip' action.  I 
can't guess what 'modip' is even supposed to mean, let alone how it's 
supposed to work?

cheers, Ian