Debian bug report logs - #1660
ping doesn't work with broadcast addresses

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Subject: Re: Bug#1660: ping doesn't work with broadcast addresses
To: marekm@i17linuxb.ists.pwr.wroc.pl
Date: Wed, 18 Oct 1995 00:00:26 +0100 (MET)
From: "Peter Tobias" <tobias@server.et-inf.fho-emden.de>
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In-Reply-To: <199510122057.VAA32259@i17linuxb.ists.pwr.wroc.pl> from "Marek Michalkiewicz" at Oct 12, 95 09:57:39 pm
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Marek Michalkiewicz wrote:
> Package: netbase
> Version: 1.17-1
> 
> On several other systems I can use ping with a broadcast address to see
> what machines on the local network are up and running.  This doesn't
> work on Linux - I get "sendto: Permission denied".  It is necessary to
> set the SO_BROADCAST socket option for this to work.  Similar change
> would probably be nice for fping too.
> 
> While we are at it, can we make ping, traceroute (and maybe some other
> setuid programs which can run for a long time and need root privileges
> only at startup), drop root privileges when no longer needed?  Just do
> setuid(getuid()) - the advantage is that ps shows who is running ping.

I'll close this bug report with this message. All bugs you mentioned
have been fixed.


Peter
 
PS: fping does not support broadcast pings at all. According to the
    author is this behavior intentional.

-- 
 Peter Tobias                                EMail:
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From: Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl>
Message-Id: <199510122057.VAA32259@i17linuxb.ists.pwr.wroc.pl>
Subject: ping doesn't work with broadcast addresses
To: debian-bugs@pixar.com
Date: Thu, 12 Oct 1995 21:57:39 +0100 (MET)
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Package: netbase
Version: 1.17-1

On several other systems I can use ping with a broadcast address to see
what machines on the local network are up and running.  This doesn't
work on Linux - I get "sendto: Permission denied".  It is necessary to
set the SO_BROADCAST socket option for this to work.  Similar change
would probably be nice for fping too.

While we are at it, can we make ping, traceroute (and maybe some other
setuid programs which can run for a long time and need root privileges
only at startup), drop root privileges when no longer needed?  Just do
setuid(getuid()) - the advantage is that ps shows who is running ping.

The patch for ping, with both of the above changes, follows.

Marek

diff -urN ping-5.9.orig/ping.c ping-5.9/ping.c
--- ping-5.9.orig/ping.c	Sat Jan 14 01:24:01 1995
+++ ping-5.9/ping.c	Sat Oct  7 01:12:08 1995
@@ -333,6 +333,8 @@
 	if (options & F_SO_DONTROUTE)
 		(void)setsockopt(s, SOL_SOCKET, SO_DONTROUTE, (char *)&hold,
 		    sizeof(hold));
+	/* this is necessary for broadcast addresses to work */
+	setsockopt(s, SOL_SOCKET, SO_BROADCAST, (char *)&hold, sizeof(hold));
 
 	/* record route option */
 	if (options & F_RROUTE) {
@@ -385,6 +387,8 @@
 		}
 	}
 #endif
+	/* just in case, and to make ps show who is running ping */
+	setuid(getuid());
 
 	if (to->sin_family == AF_INET)
 		(void)printf("PING %s (%s): %d data bytes\n", hostname,