Date: Mon, 17 Nov 2008 12:02:50 -0800 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Steven Hartland <killing@multiplay.co.uk> Cc: freebsd-stable@freebsd.org Subject: Re: Possible regression in ifconfig under7.0 - removes valid default route Message-ID: <20081117200250.GA38619@icarus.home.lan> In-Reply-To: <89DE4FDF67DC40AE88477897DF4CD0E7@multiplay.co.uk> References: <89DE4FDF67DC40AE88477897DF4CD0E7@multiplay.co.uk>
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On Mon, Nov 17, 2008 at 07:11:50PM -0000, Steven Hartland wrote: > I believe there "may be" a regression in the behaviour of ifconfig or > possibly just something I've never experienced before. > > Basically when changing the IP of one of our machines, it suddenly > became inaccessible. After some investigation it turned out the machine > was inaccessible from anything other than the local VLAN and continued > diagnostics determined that the process of changing the IP had also > removed the default route. > > This was clearly unexpected behaviour as the new IP was on the same > VLAN as the old IP and hence no routing table updates should be > required. > > I don't have any older machines to test this on but I believe we have > done this procedure in the past without any such issues so wanted to > raise it here to see if anyone else has had experience with it. > > Even if this isn't a regression it may well be something worth fixing > as its quite unexpected behaviour which could render a machine totally > inaccessible. I can try to reproduce this if you'd like, on a VMware session. One case where the default route could be (I haven't checked) removed: some NIC drivers in the past, when changing the "primary IP" (first IP shown in ifconfig for an interface), would actually bring down the entire interface (e.g. ifconfig XXX down) then back up again a second or two later. dmesg on your machine would be able to confirm whether or not this is happening. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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