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Date: Sun, 21 Jan 2001 21:25:25 +0100 (CET)
From: Jesper Skriver <jesper@skriver.dk>
Reply-To: Jesper Skriver <jesper@skriver.dk>
To: FreeBSD-gnats-submit@freebsd.org
Cc:
Subject: Sent ICMP unreach when packet not for us is received, and forwarding is disabled
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>Number:         24512
>Category:       kern
>Synopsis:       Sent ICMP unreach when packet not for us is received, and forwarding is disabled
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    jesper
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Jan 21 12:30:01 PST 2001
>Closed-Date:    Sat Jul 19 12:24:17 PDT 2003
>Last-Modified:  Sat Jul 19 12:24:17 PDT 2003
>Originator:     Jesper Skriver <jesper@skriver.dk>
>Release:        FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:
System: FreeBSD tam 5.0-CURRENT FreeBSD 5.0-CURRENT #0: Sun Jan 21 20:46:42 CET 2001 root@tam:/usr/obj/usr/src/sys/TAM2 i386


	
>Description:

	Sent a ICMP unreachable instead of dropping it silent, if we receive a 
packet not for us, and forwarding disabled.

>How-To-Repeat:
	
>Fix:

	Apply this diff

--- sys/netinet/ip_input.c.old	Sun Jan 21 19:09:58 2001
+++ sys/netinet/ip_input.c	Sun Jan 21 20:39:39 2001
@@ -124,6 +124,10 @@
 	&ip_keepfaith,	0,
 	"Enable packet capture for FAITH IPv4->IPv6 translater daemon");
 
+int	ip_sent_unreach = 1;
+SYSCTL_INT(_net_inet_ip, OID_AUTO, sent_unreach, CTLFLAG_RW, &ip_sent_unreach, 
+	0, "Sent ICMP unreach when packet not for us rx, and forwarding disabled");
+
 #ifdef DIAGNOSTIC
 static int	ipprintfs = 0;
 #endif
@@ -575,7 +579,14 @@
 	 */
 	if (ipforwarding == 0) {
 		ipstat.ips_cantforward++;
-		m_freem(m);
+		/*
+		 * If we receive a packet not for us, and forwarding disabled
+		 * sent a ICMP host unreachable back to the source.
+		 */
+		if (ip_sent_unreach != 0)
+			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
+		else
+			m_freem(m);
 	} else
 		ip_forward(m, 0);
 #ifdef IPFIREWALL_FORWARD

>Release-Note:
>Audit-Trail:

slightly different fix committed with approval of jlemon
State-Changed-From-To: open->closed 
State-Changed-By: jesper 
State-Changed-When: Tue Feb 20 14:03:28 PST 2001 
State-Changed-Why:  
Slighly different fix committed after approval from jlemon 


http://www.freebsd.org/cgi/query-pr.cgi?pr=24512 
State-Changed-From-To: closed->open 
State-Changed-By: ru 
State-Changed-When: Wed Feb 21 09:09:50 PST 2001 
State-Changed-Why:  
The change was backed out since it violates Host Requirements. 


Responsible-Changed-From-To: freebsd-bugs->jesper 
Responsible-Changed-By: ru 
Responsible-Changed-When: Wed Feb 21 09:09:50 PST 2001 
Responsible-Changed-Why:  
Jesper is going to find a better solution. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=24512 
State-Changed-From-To: open->analyzed 
State-Changed-By: jesper 
State-Changed-When: Wed Feb 21 09:18:00 PST 2001 
State-Changed-Why:  
Working on a better solution after the backout of the 
previous commit. 


http://www.freebsd.org/cgi/query-pr.cgi?pr=24512 
State-Changed-From-To: analyzed->closed 
State-Changed-By: jesper 
State-Changed-When: Sat Jul 19 12:23:49 PDT 2003 
State-Changed-Why:  
Not the right solution 

http://www.freebsd.org/cgi/query-pr.cgi?pr=24512 
>Unformatted:
