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Date: Sat, 27 Jan 2001 20:06:24 +0100 (CET)
From: klaus@winf.htu.tuwien.ac.at
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Subject: bin/24683: obscure natd(8) error message
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>Number:         24683
>Category:       bin
>Synopsis:       obscure natd(8) error message
>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:   Sat Jan 27 11:10:04 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Klaus A. Brunner
>Release:        FreeBSD 4.2-STABLE i386
>Organization:
HTU Wien, FS WInf
>Environment:

	FreeBSD (any version?) running natd(8)

>Description:

There is a rather annoying problem with natd(8)'s error message
"unable to write packet back (...)". This error message may occur
when a host is down, or when a firewall rule prevents natd from
completing a sendto(). The problem is not that this error message 
exists, but that it does not give *any* detail (_which_ packet, 
addresses?).

The problem is frequently reported on -questions and other lists,
and it's also been bugging me for a while because I just couldn't
figure out what was happening from ipfw logs et al.

>How-To-Repeat:

(see description)
One scenario where this seems to happen frequently is when you're 
running Samba and natd on the same box.

>Fix:

This simple patch makes the error message verbose enough to be useful:

--- natd.c	Sat Jan 27 19:48:30 2001
+++ /tmp/natd.c	Sat Jan 27 19:38:50 2001
@@ -586,7 +586,7 @@
 static void FlushPacketBuffer (int fd)
 {
 	int			wrote;
-	char			msgBuf[80];
+	char			msgBuf[160];
 /*
  * Put packet back for processing.
  */
@@ -616,7 +616,8 @@
 		}
 		else {
 
-			sprintf (msgBuf, "failed to write packet back");
+			sprintf (msgBuf, "failed to write packet back (%s)", 
+                                 FormatPacket((struct ip*)packetBuf));
 			Warn (msgBuf);
 		}
 	}



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


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