Re: [K12OSN] eth alias help

["Christopher K. Johnson" <ckjohnson gwi net>]

Les Mikesell wrote:

> On Thu, 2004-02-26 at 13:55, Steve Wright wrote:
>  
>
> > > Ok....Right now in my mail server I have 2 separate 10/100 nics recieving mail
> > > for 2 separate domains. If I take those out and put one gig nic in...can I
> > > create an alias (like eth 0:1) for the other domain and have things work like
> > > normal from the same nic? I assume I can but want to make sure.
> > >      
> > Yes, you can, but it is the old way to do it.
> >    
>
> But RedHat/Fedora systems have a handy GUI tool for interfaces
> and aliases in redhat-config-network, and if you use it
> the ifup/ifdown wrappers work and you can set it up to
> automatically start at bootup.
>
>  
>
> > Simply add both addresses to the interface.  The interface will
> > establish itself as usual, and then add the secondary IP address
> > directly, thusly ;
> >
> >
> > # ip address add 192.168.n.254/24 dev eth0
> >    
>
> The one thing I have sometimes had trouble with is that
> with multiple addresses on the same subnet the 'wrong'
> one may be used as the source address on outbound
> connections.  Is there a way to control that?
>
> ---
>  Les Mikesell
>   les futuresource com
>  
Absolutely. Below are sample ifcfg-eth0 and ifcfg-eth0:0 that 
illustrate.  The trick is in the NO_ALIASROUTING=yes parameter, which by 
putting it on the main interface, is an inherited setting on the aliased 
interfaces.

-------- ifcfg-eth0 -----------
NAME="Public (insecure) Interface"
DEVICE=eth0
IPADDR=x.x.x.x
NETMASK=255.255.255.240
NETWORK=x.x.x.y
BOOTPROTO=none
ONBOOT=yes
USERCTL=no
NO_ALIASROUTING=yes
-------- end ifcfg-eth0 --------

-------- ifcfg-eth0:0 ----------
NAME="Public (insecure) Interface - 1st Alternative Address"
DEVICE=eth0:0
# Only the differences from base interface need be configured for alias
IPADDR=x.x.x.z
-------- end ifcfg-eth0:0 -------

Chris

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