Date: Sat, 6 Jul 2002 03:32:57 -0400 From: Jonathan Chen <jon@FreeBSD.org> To: "Jin Guojun[DSD]" <j_guojun@lbl.gov> Cc: freebsd-bugs@FreeBSD.org Subject: Re: bin/21292: ifconfig warn but does duplicate IP address Message-ID: <20020706033257.D58146@porthos.spock.org> In-Reply-To: <3D25FD1B.4AF0217@lbl.gov>; from j_guojun@lbl.gov on Fri, Jul 05, 2002 at 01:10:03PM -0700 References: <200207051941.g65Jf3x2084537@freefall.freebsd.org> <3D25FD1B.4AF0217@lbl.gov>
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On Fri, Jul 05, 2002 at 01:10:03PM -0700, Jin Guojun[DSD] wrote: > Jonathan Chen wrote: > > > > Synopsis: ifconfig warn but does duplicate IP address > > > > State-Changed-From-To: open->closed > > State-Changed-By: jon > > State-Changed-When: Fri Jul 5 12:40:04 PDT 2002 > > State-Changed-Why: > > fixed [src/sys/netinet/in.c 1.44.2.8] > > > > http://www.freebsd.org/cgi/query-pr.cgi?pr=21292 > > I am not sure if this is completely fixed -- it is fixed if same netmask > is given. If a different netmask is used, the same IP can still be > assigned to a different interface, which is meaningless even they are > in different class. > > I think this type of checking should be simple IP only; ie., it should not > invoke netmask: The checking you refer to is actually done on the routing table. Generally, If you have two interfaces directly connected to the same subnet, the kernel cannot decide which interface to send packets through, hence the 'file exists' error. There is nothing inherently wrong with two interfaces having the same IP address. For instance, a CIDR router might use the same IP address for both the larger and smaller subnet, and multiple point-to-point interfaces in a machine will often have the same IP. Instead of having the kernel tell you what you don't want to do, I perfer the much simpler motto: If you don't want to do it, then don't do it. -Jon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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