[CentOS] Hidden networking device configuration

Fri Jan 27 14:30:34 UTC 2006
Bowie Bailey <Bowie_Bailey at BUC.com>

Rodrigo Barbosa wrote:
> On Thu, Jan 26, 2006 at 04:15:59PM -0500, Bowie Bailey wrote:
> > I am trying to configure load balancing for a couple of CentOS4
> > servers. In order to make it work, I need to add a hidden
> > networking device on 
> > each server with the virtual IP.  I found the following
> > instructions on linuxvirtualserver.org for doing this, but they
> > don't work. 
> > 
> >     echo 1 > /proc/sys/net/ipv4/ip_forward
> >     ifconfig dummy0 up
> >     echo 1 > /proc/sys/net/ipv4/conf/all/hidden
> >     echo 1 > /proc/sys/net/ipv4/conf/dummy0/hidden
> >     ifconfig dummy0:0 up
> > 
> > When I try to write to /proc/sys/net/ipv4/conf/all/hidden, the
> > system refuses to let me create the file.  I'm logged in as root,
> > so why am I having permission problems? 
> > 
> > Also, I believe these instructions are for 2.2 or 2.4 kernels. 
> > Have things changed with 2.6?
> No, things are exactly the same. Meaning that LVS is a separated patch
> that is not included either on the stock kernel or the RHEL one.
> If you really want to use LVS, you will have to apply the patch.

Hmm... I saw a reference to a kernel patch, but I thought the patch was
for the server.  I am actually not using a Linux LVS server, I am using
a Foundry ServerIron to do the load balancing.  It works great for
standard balancing, but now I need to do direct routing to balance two
CentOS4 servers.  The instructions that came with the ServerIron just
gave a single ifconfig command to set it up (which royally screwed up
the networking).

Do I need to install the kernel patch on these machines?  And why would
that affect the permissions problem I was seeing?  As root, I should be
able to create a file in any directory.  It may not do what I expect if
the functionality is not in the kernel, but I should be able to create
the file.