Date: Sat, 5 Sep 1998 12:51:30 -0400 (EDT) From: Robert Watson <robert@cyrus.watson.org> To: freebsd-net@FreeBSD.ORG Subject: netmask of 0 not permitted (3.0-current) Message-ID: <Pine.BSF.3.96.980905124503.1068C-100000@fledge.watson.org>
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This morning I was plugged into a network, and wanted to figure out what
hosts on the network were in which subnets. In particular, I knew that
several hosts on the subnet believed they were on different subnets due to
a configuration problem. Well, I thought, I'll just set up my ethernet
device to believe that all IP addresses are local so I don't get a "no
route to host" without a default router set.
But then I ran into a problem:
ifconfig ep0 netmask 0.0.0.0
ifconfig ep0
ep0: flags=a843<UP,BROADCAST,RUNNING,SIMPLEX,LINK1,MULTICAST> mtu 1500
inet 192.168.10.21 netmask 0xffffff00 broadcast 192.168.10.255
ether 00:a0:24:60:31:9c
I can ifconfig to almost 0:
ep0: flags=a843<UP,BROADCAST,RUNNING,SIMPLEX,LINK1,MULTICAST> mtu 1500
inet 192.168.10.21 netmask 0x80000000 broadcast 255.255.255.255
ether 00:a0:24:60:31:9c
but not to 0 itself.
It seems to me that a netmask of 0 is not illegitimate, as I might want to
have all packets go to the local network.
Am I doing something wrong? :)
Robert N Watson
Carnegie Mellon University http://www.cmu.edu/
TIS Labs at Network Associates, Inc. http://www.tis.com/
SafePort Network Services http://www.safeport.com/
robert@fledge.watson.org http://www.watson.org/~robert/
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