Date: Sun, 21 Jan 2001 21:25:25 +0100 (CET) From: Jesper Skriver <jesper@skriver.dk> To: FreeBSD-gnats-submit@freebsd.org Subject: kern/24512: Sent ICMP unreach when packet not for us is received, and forwarding is disabled Message-ID: <200101212025.f0LKPPB00717@tam.skriver.dk>
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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: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Sun Jan 21 12:30:01 PST 2001
>Closed-Date:
>Last-Modified:
>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:
>Unformatted:
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