On Tue, Apr 1, 2008 at 1:06 PM, Ted Cooper <eximX1211@???> wrote:
>
> Gabriel Harrison wrote:
> >> It's there .. just have to find it
> >
> > It looks like exim is somehow seeing the listener on the vserver host
> > machine.
> >
> > If I stop it on one then the other will start! I'm now confused, I thought
> > any vserver was isolated from the host.
> >
> > What I am trying to achieve is for the vservers to only bind to localhost
> > but it is this that is conflicting with the listener on the host, which is
> > also localhost only.
> >
> > How is it that exim sees the host binding from the vserver and vise-versa
> > but netstat doesn't?
>
> Are you running exim in the host OS at all? From the few moments I was
> reading about vserver it sounds like it sets up an alias interface in
> the host OS to use as the network IF for the vserver. If you bind on
> port 25 of the host version of the alias then the vserver will be unable
> to bind to the same port on its own version of the interface .... or
> that's the gist I'm getting.
I've getting the same feeling from the further reading I've been doing too.
This thread describes something similar
http://www.paul.sladen.org/vserver/archives/200505/0249.html
Exim is obviously doing something slightly different to other daemons
like mysql and ssh. These two are bound to all IPs on the host and the
vservers and working ok. I'm still learning a lot about vservers but I
can't understand how exim is seeing the bindings from the host when
ssh and mysql don't.
> ie no binding 0.0.0.0:25 on the host OS
>
> You *may* also have to create a "localhost" for each an every vserver if
> they are somehow sharing localhost. lo:0 == 127.0.0.2 etc
Excellent, thank you. I'll try that.
> If you want to test all this stuff out, find something a like NetCat and
> use it in listen mode to bind to ports in different places and see where
> the clashes are.
If the 127.0.0.2 solution works I'll have to save this for a quiet
day. It would be good to get to the bottom of though!
> I really can't see any advantage to use this vserver software in the
> slightest .. it doesn't seem like a real virtual server like the ones
> you can rent/buy from hosting companies.
We are using the virtual servers to make the transition from
development to testing to production easier. Everytime we want to
migrate our development system to the testing system all we do
(ignoring backups) is.
- ssh into host
then:
- host# vserver testing delete
- host# dupvserver -v --from unstable --to testing --ip aaa.bbb.ccc.ddd
Apart from being quick it saves loads of time making sure the test
environment is identical to the development environment. The
dupvserver command changes all the references to the old hostname to
the new one too.
I'm reliable informed that some of the commercial virtual server
hosting providers use debian vserver.
> This is why I use dedicated
> servers :P
If only I could persuade the boss...
Gabriel
