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Re: RHEL5/CentOS5 KS Network Oddities (ifcfg-* gets re-written)



Steve Robson wrote:
Subject: RHEL5/CentOS5 KS Network Oddities (ifcfg-* gets re-written)
From: "kslist" <kslist devo com>
Date: Wed, 26 Sep 2007 01:02:53 +0200 (CEST)
To: kickstart-list redhat com

Hello KSers,

I am using my Kickstart script that I have adapted from RHEL 2.1, 3, and 4
now on CentOS 5. CentOS 5 behaves differently when it comes to network
configuration.

In essence: AFTER the successfull installation, during the first startup
of the OS, something desctroys my network configuration. Specifically, the
files that I have directly written in my %post script:
/etc/sysconfig/network
/etc/sysconfig/network-scripts/ifcfg-eth0
/etc/sysconfig/network-scripts/ifcfg-eth1
/etc/hosts
/etc/resolve.conf
are modified, and in the case of the ifcfg-* scripts, my scripts are moved to a *.bak file (which have a datestamp later than the files I created via
%post, and which correspond to the firstboot) and a completely newfile is
created in its place.

The network configuration that replaces my own is one for DHCP.

My guess is that this is a result of a change in behaviour of the
"network" option. To quote from the RHEL 5 Installation Guide:

"Configures network information for the system. If the kickstart
installation does not require networking (in other words, it is not
installed over NFS, HTTP, or FTP), networking is not configured for the
system. If the installation does require networking and network
information is not provided in the kickstart file, the installation
program assumes that the installation should be done over eth0 via a
dynamic IP address (BOOTP/DHCP), and configures the final, installed
system to determine its IP address dynamically. The network option
configures networking information for kickstart installations via a
network as well as for the installed system."

Now, I see a problem here:
- I use DHCP to install the system (via Kickstart)
- I however do NOT want to run the subsequently installed OS to use DHCP.

I would say that is a very very normal thing to want.

Completely normal, I do it all the time!

Typically I use one of the following "network" directives, depending how I want the resulting client to behave. Beware that if you choose to statically address the target client using this method, its IP address must be on the same subnet as your KS server.

network --device=eth0 --bootproto=dhcp --hostname=lnx-blah
or
network --bootproto static --device=eth0 --gateway=I.P.of.GW --ip=I.P.of.client --nameserver=IP.of.DNS.server --netmask=I.P.of.netmask --onboot=on --hostname=lnx-blah

Hope this helps, see here for full detail: http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/Installation_Guide-en-US/s1-kickstart2-options.html


I think what the OP is referring to is network config files that were changed in %post being squashed after reboot. I noticed this as well when I first started building my configs for RHEL5, but since we haven't been using them, I never looked into it.

So for example, you use DHCP during the install, then set the IP's in the %post. When the server reboots, it seems to overwrite any changes you made to the /etc/sysconfig/network-scripts/ifcfg-* files.

Hope that helps clarify.

-Dan


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