Date: Tue, 24 Jul 2007 00:59:25 -0700 From: Julian Elischer <julian@elischer.org> To: Evren Yurtesen <yurtesen@ispro.net> Cc: freebsd-hackers@freebsd.org, Jeremy Chadwick <koitsu@FreeBSD.org> Subject: Re: alias netmask bug? Message-ID: <46A5B15D.80805@elischer.org> In-Reply-To: <46A5AEED.4080104@ispro.net> References: <46A5492E.90500@ispro.net> <20070724045054.GA81397@eos.sc1.parodius.com> <46A5AEED.4080104@ispro.net>
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Evren Yurtesen wrote: > Jeremy Chadwick wrote: >> On Tue, Jul 24, 2007 at 03:34:54AM +0300, Evren Yurtesen wrote: >>> I remember from earlier versions of FreeBSD that it had a >>> restriction about alias IP netmasks (somewhere in 3.x,4.x days)... >>> >>> as explained here: >>> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-virtual-hosts.html >>> >>> >>> However I tried on the loopback interface to add a 2nd IP with the >>> same netmask as the original IP and it accepts it fine. (on 6.2) >>> >>> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384 >>> inet 127.0.0.1 netmask 0xff000000 >>> inet 127.0.0.2 netmask 0xff000000 >>> >>> Is FreeBSD allowing this a bug or ??? >> >> It's not a bug. Why did you disregard the instructions, though? > > I didnt disregard the instructions. I read somebody suggesting not using > 255.255.255.255 in some forum. Then I tried it out and FreeBSD accepted > the netmask for the alias IP. > > Why does FreeBSD accept such netmask which can cause problems when > earlier it was rejecting it? > >>> If this is not a bug. What happens if an interface which is >>> connecting to the machine has 2 IP addresses with same netmask which >>> is not 255.255.255.255? Does FreeBSD use each IP randomly? I'm not sure but it is possible that lo0 is treated more like a P2P interface in which case the netmask is not used in routing decisions. >> >> Don't know, but my guess is no, it probably does not use "each IP >> randomly", and I cannot even fathom the network breakage that would >> ensue as a result of such. > > I understand, I will try to test that sometime to see what FreeBSD does > in this kind of situation. > > However, it might be nice if ifconfig did not allow this kind of wrong > setting. > > Thanks, > Evren > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
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