On Sat, 2009-05-02 at 00:40 +0200, Herbert Poetzl wrote:
> On Fri, May 01, 2009 at 06:05:15PM -0400, John A. Sullivan III wrote:
> > On Fri, 2009-05-01 at 23:34 +0200, Herbert Poetzl wrote:
> > > On Fri, May 01, 2009 at 04:48:12AM -0400, John A. Sullivan III wrote:
> > > > Hello, all. I'd like to confirm that I understand the way vserver
> > > > 2.3 is handling localhost and the loopback address.
> > > > Am I correct to understand that, unlike earlier version, the
> > > > default kernel compilation makes it safe to use 127.0.0.1 on a
> > > > guest? That is, each one is uniquely mapped and does not interfere
> > > > with the host listening in 127.0.0.1? We can thus set our
> > > > /etc/hosts files to use: 127.0.0.1 localhost localhost.localdomain
> > > > etc . . .?
> > > > However, is it also true that daemon bindings to localhost will
> > > > still be made to the address in /etc/vservers/<guest>/interfaces/0
> > > > and will not include 127.0.0.1 unless explicitly bound?
> > > > I ask because we were delighted to realize we could simplify
> > > > our zimbra installation by leaving /etc/hosts at 127.0.0.1
> > > > for localhost. We then started retrofitting our other servers
> > > > to do the same. Some of our servers communicate with sshd on
> > > > 127.0.0.1. We had changed the configuration files to bind them
> > > > to the non-loopback address, e.g., 192.168.1.10 because of our
> > > > old understanding of 127.0.0.1. We also changed sshd_config by
> > > > removing the ListenAddress 192.168.1.10 so that it goes back to
> > > > the default of binding to all interfaces.
> > > > This broke those applications. When we do a netstat -tln on the
> > > > vserver guests, it shows sshd listening only on 192.168.1.10 (as
> > > > an example) and not 0.0.0.0.
> > > if you disable the single IP special casing, this
> > > will change to the expected behaviour ...
> > Sorry to be showing my ignorance again but what is "single IP special
> > casing" that I should be disabling? Thanks - John
> A Linux-VServer context flag, which controls the
> behaviour in case a single IP is assigned to a guest
> (which can be optimized by replacing 0.0.0.0 with
> that single IP, instead of keeping a list to check
> against) ...
> (see nflags, SINGLE_IP)
> note, that in the kernel config, you can also set the
> default behaviour (VSERVER_AUTO_SINGLE) which, when
> enabled does set that flag automatically
Hmm . . . so then it sounds like one could ideally turn off both
automatic settings in the kernel and use the flags to have the greatest
flexibility to choose which treatment is best for each application. Am
I finally starting to get it? - John
-- John A. Sullivan III Open Source Development Corporation +1 207-985-7880 firstname.lastname@example.org http://www.spiritualoutreach.com Making Christianity intelligible to secular societyReceived on Fri May 1 23:49:47 2009