Re: default LDM to CheckHostIP=no

On Mon, Apr 04, 2011 at 01:30:07PM +0300, Michael Shigorin wrote:
> On Fri, Apr 01, 2011 at 12:17:47PM -0700, Vagrant Cascadian wrote:
> > i've thought for some time we should consider defaulting to
> > ignore the host ip address, to reduce the need to run
> > ltsp-update-sshkeys whenever the ip address changes.
> > 
> > security-wise, i'm not sure what we gain by erroring out
> > whenever the ip address changes- as long as we're connecting to
> > a known hostname and host key pair, the connection should be
> > mighty secure.
> 
> Well, a successful attack might involve either taking over DNS
> or (which might prove easier) pushing rogue DHCP server pointing
> to rogue DNS server but otherwise replicating the proper one's
> setup.  This dhcpd should be significantly faster (or employ one
> more trick if it's not employed by proper one yet) to achieve the
> result, and this rather requires either physical access to the
> network or breaching at least one fast enough host/VM on it to
> continue.  (BTW this could also be discovered via buggy PXE BIOS
> like some e100 due to them ignoring next-server and trying to
> TFTP into a DHCP server nevertheless, but then again it could
> be covered up by replicating tftpd too)

sure, but in order for that to cause problems, they would ALSO have to 
compromise the server's host key... at which point the fact that the ip 
address changed isn't really what i'd be worrying about; they have control 
of your server at that point.

though, of course, in irc Gadi pointed out to me that our default behavior is 
to use the IP address directly, so CheckHostIP wouldn't gain us much. hrm.


live well,
  vagrant

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