[ale] IP Aliasing (please help!)

[Ryan Fish]

Subject: Re: [ale] IP Aliasing (please help!)

On Wed, 2005-05-18 at 17:59 -0400, Ryan Fish wrote:
> Hello all,
> 
>  
> 
> I am in need of temporarily setting up IP Aliasing on a web server to
> allow traffic from IPs on two different subnets of the same class C to
> be answered by this one server.  My problem lies in not knowing how or
> where to add the second Default Gateway and Network ID.  I figure the
> Network ID would just be setup in ifcfg-eth1:N though.

Do you really need a second default gateway?   Once you add the aliased
IP it will create a route for it's subnet that should suffice most
cases.   In order to setup the second (third, etc..) interface you need
to alias the "dummy" module.  One of my /etc/modules.conf (Redhat) has
entries like this: "alias dummyX dummy" where dummyX is the name of the
aliased interface (i.e. alias0, or dummy0).  You then need to add
(again, assuming
Redhat) /etc/sysconfig/network-scripts/ifcfg-eth0-range0 

See this for details:
https://www.redhat.com/archives/fedora-list/2003-December/msg02964.html

-Jim P.


----
Jim,

I am still lost here.  So, using the IP ranges shown below, I can just add a
range and everything will know where to route automagically?  I would need
to actually add two then since I need to leave one IP (.203) out of the
equation as it resides on the only name server that will be in place during
the server migration that is causing my headaches at this time...

The server with this temporary setup is a web server running Apache on RHEL3
ES.  It is being used to serve a "We are working on things right now" page
until the migration is complete.  This help make it make are more sense in
any way?

-Ryan
----
 
> Subnet one
> Network ID = xxx.xxx.242.192
> Subnet Mask = 255.255.255.224
> Default Gateway = xxx.xxx.242.193
> Available IPs = xxx.xxx.242.195 - xxx.xxx.242.222
> 
> Subnet two
> Network ID = xxx.xxx.242.224
> Subnet Mask = 255.255.255.224
> Default Gateway = xxx.xxx.242.195 (not sure how this can be though
> since it is listed as a usable IP above)
> Available IPs = xxx.xxx.242.225 - xxx.xxx.242.254