kern/103950: Broadcast packets are not forwarded

[DEVILLE Damien]

>Number:         103950
>Category:       kern
>Synopsis:       Broadcast packets are not forwarded
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Oct 03 15:40:22 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     DEVILLE Damien
>Release:        FreeBSD 6.1-STABLE i386
>Organization:
NETASQ
>Environment:
System: FreeBSD darkstar.netasq.com 6.1-STABLE FreeBSD 6.1-STABLE #1: Thu May 11 11:43:31 CEST 2006 vanhu at darkstar.netasq.com:/home/vanhu/work/FreeBSD/src-RELENG6/sys/i386/compile/GENERIC.IPSEC i386


	
>Description:
On a FreeBSD gate, broadcasts received on an interface with a destination
belonging to another interface are not correctly forwarded because
IP_ALLOWBROADCAST is not set in ip_output() call from ip_forward().

>How-To-Repeat:
Set up a gate with 2 NICs (for example 192.168.1.0/24 and 192.168.2.0/24).

>From a host on 192.168.1.0/24, do a ping to 192.168.2.255.

The packet will go through ip_forward(), but will be dropped in
ip_output().


>Fix:
--- sys/netinet/ip_input.c.orig     Fri Sep 29 11:35:14 2006
+++ sys/netinet/ip_input.c  Fri Sep 29 11:35:22 2006
@@ -2006,7 +2006,7 @@
                        RTFREE(rt);
        }

-       error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
+       error = ip_output(m, NULL, NULL, IP_FORWARDING|IP_ALLOWBROADCAST, NULL, NULL);
        if (error)
                ipstat.ips_cantforward++;
        else {

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