docs/169367: ipfilter section of handbook has an error in the ipnat rules example

[Robert Simmons]

>Number:         169367
>Category:       docs
>Synopsis:       ipfilter section of handbook has an error in the ipnat rules example
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Jun 24 09:30:06 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Robert Simmons
>Release:        9.0-RELEASE
>Organization:
>Environment:
FreeBSD test 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue Jan  3 07:15:25 UTC 2012     root at obrian.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
>Description:
Section 31.5.21.1 IPNAT Rules in the Handbook contains the following example rule line for FTP proxy:

map dc0 0.0.0.0/0 -> 0/32 proxy port 21 ftp/tcp

This is wrong, and leads to an error when the rules files is loaded:
syntax error error at "", line 1
>How-To-Repeat:
try to load the following ipnat rule:

map dc0 0.0.0.0/0 -> 0/32 proxy port 21 ftp/tcp
>Fix:
According to the ipfilter docs, this line should read:

map dc0 0/0 -> 0/32 proxy port 21 ftp/tcp

This does not produce an error, and when I run ipnat -l:

# ipnat -l
List of active MAP/Redirect filters:
map em0 0.0.0.0/0 -> 0.0.0.0/32 proxy port ftp ftp/tcp

>Release-Note:
>Audit-Trail:
>Unformatted: