Creation of dummy ipv6 IP address during kickstart

Rocky Linux General
1

Hi,

We’re trying to create ipv6 loopback IP addresses in Rocky 8 during the kickstart with a shell script.
The goal would be that these IP’s are available on first boot.
Previously in CentOS 7 we added them to the ifcfg-lo but this doesn’t work any longer.
So we tried the following by executing this script during kickstart installation via Foreman;

#!/bin/sh
#an IPV6 adress for each instance
#The …99 adress will be used for the multi instance when using the apache reverse proxy (in the future)

echo “]] <ipv6.sh> Adding IPV6 address to loopback interface for internal use”

nmcli c add type dummy ifname gateway-multi save yes
ls -l /etc/NetworkManager/system-connections

for x in 0001 0002
do
nmcli c modify dummy-gateway-multi +ipv6.addresses 2001:0db8:1234:0000:0000:0000:0000:$x/128
done

ls -l /etc/NetworkManager/system-connections
nmcli c modify dummy-gateway-multi ipv6.addr-gen-mode eui64
nmcli c modify dummy-gateway-multi ipv6.method static
ls -l /etc/NetworkManager/system-connections
nmcli c show dummy-gateway-multi
ls -l /etc/NetworkManager/system-connections
ifconfig
systemctl restart NetworkManager
ls -l /etc/NetworkManager/system-connections
ifconfig
ls -l /etc/NetworkManager/system-connections

echo “]] <ipv6.sh> Adding IPV6 address done”

Some lines in the shell script have been added for troubleshooting purpose.
Basically it comes down to these commands;

nmcli c add type dummy ifname gateway-multi save yes
nmcli c modify dummy-gateway-multi +ipv6.addresses 2001:0db8:1234:0000:0000:0000:0000:0001/128
nmcli c modify dummy-gateway-multi ipv6.addr-gen-mode eui64
nmcli c modify dummy-gateway-multi ipv6.method static
nmcli c show dummy-gateway-multi
ifconfig

If above commands are executed in an already build vm they are persistent and the IP’s are still present after reboot.
However our executed scripts logs the following;

MicrosoftTeams-image (1)
MicrosoftTeams-image (1)1113×2259 250 KB

ls command shows that the file is not actually created in /etc/NetworkManager/system-connections.
And also nmcli command show the ipv6 addresses while ifconfig only shows the interface but the additional ipv6 addresses are not there.

Once booted, interface dummy-gateway-multi is nowhere to be found.
What are we doing wrong ?

2

First, I have no idea what a “loopback address” is (apart from the localhost.localdomain).

Second, one of the default packages makes NetworkManager to support the RHEL legacy /etc/sysconfig/network-scripts/ifcfg-* format.
As example, an system, where install did not define (and save) connections does autodefine connections for interfaces by default (but does not save). Once you modify such connection, it will be saved as /etc/sysconfig/network-scripts/ifcfg-$devname

nmcli can give multiple options on oneliner:

nmcli c add type dummy ifname gateway-multi  ipv6.method static +ipv6.addresses 2001:0db8:1234:0000:0000:0000:0000:0001/128 ipv6.addr-gen-mode eui64

It makes sense to initialize all values on creation, rather than modify later?

RHEL doc says that you have to set both IPv4 and IPv6: Chapter 24. Creating a dummy interface Red Hat Enterprise Linux 8 | Red Hat Customer Portal
For example:

nmcli c add type dummy ifname gateway-multi  ipv4.method disabled ipv6.method static +ipv6.addresses 2001:0db8:1234:0000:0000:0000:0000:0001/128 ipv6.addr-gen-mode eui64

The net-tools (includes ifconfig) is described obsolete – since iproute2 was introduced couple decades ago.

When you write ‘kickstart’, does that use Red Hat’s ‘Kickstart’?
That kickstart can define/configure connections: Appendix B. Kickstart commands and options reference Red Hat Enterprise Linux 8 | Red Hat Customer Portal
Not sure whether it can create a dummy.

My current procedure is to do only a minimal install and then run Ansible play (in “already built” system) that installs and configures everything, including additional network touches.

3

Thanks for your feedback but it looks like what we want to achieve is no longer possible during kickstart/anaconda. So we will have to define the network interface after the build is complete.