Date: Thu, 15 Feb 2007 09:29:23 -0600 From: Brooks Davis <brooks@FreeBSD.org> To: Yar Tikhiy <yar@comp.chem.msu.su> Cc: Ceri Davies <ceri@submonkey.net>, cvs-src@FreeBSD.org, Brooks Davis <brooks@FreeBSD.org>, cvs-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: cvs commit: src/etc/rc.d hostname Message-ID: <20070215152923.GA97047@lor.one-eyed-alien.net> In-Reply-To: <20070215065743.GB20957@comp.chem.msu.su> References: <200702101313.l1ADDX8m056868@repoman.freebsd.org> <20070210205228.GE9455@submonkey.net> <20070211085317.GF13808@comp.chem.msu.su> <20070212034438.GA42410@lor.one-eyed-alien.net> <20070212120908.GN13808@comp.chem.msu.su> <20070212150333.GB50299@lor.one-eyed-alien.net> <20070213070436.GD58225@comp.chem.msu.su> <20070213161927.GC57543@lor.one-eyed-alien.net> <20070215065743.GB20957@comp.chem.msu.su>
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--5vNYLRcllDrimb99 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Feb 15, 2007 at 09:57:43AM +0300, Yar Tikhiy wrote: > On Tue, Feb 13, 2007 at 10:19:27AM -0600, Brooks Davis wrote: > > On Tue, Feb 13, 2007 at 10:04:36AM +0300, Yar Tikhiy wrote: > > > On Mon, Feb 12, 2007 at 09:03:33AM -0600, Brooks Davis wrote: > > > > On Mon, Feb 12, 2007 at 03:09:09PM +0300, Yar Tikhiy wrote: > > > > > On Sun, Feb 11, 2007 at 09:44:38PM -0600, Brooks Davis wrote: > > > > > > On Sun, Feb 11, 2007 at 11:53:17AM +0300, Yar Tikhiy wrote: > > > > > > > On Sat, Feb 10, 2007 at 08:52:28PM +0000, Ceri Davies wrote: > > > > > > > > On Sat, Feb 10, 2007 at 01:13:33PM +0000, Yar Tikhiy wrote: > > > > > > > > > yar 2007-02-10 13:13:33 UTC > > > > > > > > >=20 > > > > > > > > > FreeBSD src repository > > > > > > > > >=20 > > > > > > > > > Modified files: > > > > > > > > > etc/rc.d hostname=20 > > > > > > > > > Log: > > > > > > > > > Handle the case when the admin forgot to set $hostname, > > > > > > > > > which can happen in new installations: advise to set the > > > > > > > > > variable and refer to rc.conf(5). > > > > > > > >=20 > > > > > > > > Isn't it possible for the hostname to come via DHCP? How d= oes this > > > > > > > > behave in that case (or rather, I can see how it behaves; i= s that the > > > > > > > > right thing)? > > > > > > >=20 > > > > > > > I've never played with setting the hostname via DHCP. In my = change, > > > > > > > I just tried not to break the existing code related to DHCP. = Perhaps > > > > > > > someone using DHCP to get the hostname could shed light on th= e topic. > > > > > >=20 > > > > > > This appears mostly harmless for systems that get their hostnam= e via > > > > > > DHCP. They will get a warning, but it will otherwise work. > > > > >=20 > > > > > Now I see. The code getting $hostname via kenv from dhcp.host-na= me > > > > > is for the case when the host was booted via PXE. OTOH, a usual > > > > > DHCP client will run dhclient when it comes to setting up network > > > > > interfaces, i.e., after /etc/rc.d/hostname. Perhaps we need > > > > > a way to indicate that the hostname will be assigned automatically > > > > > and the nagging message shouldn't be emitted. E.g., in rc.conf: > > > > >=20 > > > > > hostname=3D"DHCP" > > > > >=20 > > > > > I have no idea how many Unix hosts allow their hostname to be set > > > > > via DHCP. I prefer to think that a Unix host is like a good ship: > > > > > it never changes its name while furrowing the network seas. A DH= CP > > > > > assigned hostname better fits crippled hosts such as diskless > > > > > stations etc. > > > >=20 > > > > I wrote patches many years ago that added a "default_hostname" vari= able > > > > which acted like hostname except that dhclient-script knew about it= and > > > > would change the host name to one it was give. This is the right t= hing > > > > to do IMO because many applications break horribly if hostname is n= ot > > > > set. > > >=20 > > > OTOH, booting a DHCP-configured laptop without a network connection > > > can result in its not having the hostname set at all. This can > > > warrant making $hostname a mandatory variable even for DHCP clients. > > > dhclient will change the hostname if it gets a new value from the > > > server. Changing the default hostname to a DHCP value isn't worse > > > than changing the null hostname, so the former shouldn't break any > > > apps not broken yet. I mean that dhclient may do the change a bit > > > too late into the boot sequence if the DHCP server doesn't respond > > > instantly. > >=20 > > dhclient will not change the hostname if it is set and this is probably > > the right behavior for most people. If we're going to make hostname > > manditory, we need to provide an option to that dhclient can override > > the hostname if that's what the administrator prefers. >=20 > For now, I've just taught /etc/rc.d/hostname not to emit the warning > if DHCP is used on any interface. This seems like a reasonable compromise. -- Brooks --5vNYLRcllDrimb99 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFF1HxTXY6L6fI4GtQRAsWYAJoDHH6FRhbAUyxGA9VRHIhV/7yzcQCgnzxE 7LNbcK76EbeUhaI3PAOEkCk= =ClcR -----END PGP SIGNATURE----- --5vNYLRcllDrimb99--
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