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Description of problem:
Installing RHEL 9.1, configuring the following sysctls, updating initramfs, and rebooting shows IPv6 being disabled on all interfaces after boot and the sysctl values in use as configured:
# cat /etc/sysctl.d/50-ipv6.conf
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
On the same system upgrading kernel to the latest (currently ~ RHEL 9.2) and rebooting still shows the same results.
However, after upgrading NetworkManager to the latest on the same system or doing a fresh RHEL 9.2 installation with the same configuration we see the loopback having IPv6 enabled and the related sysctl changed even when the configuration file sets it to 1:
# cat /proc/sys/net/ipv6/conf/lo/disable_ipv6
0
# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
This procedure of disabling IPv6 is documented in the RHKB article and works on RHEL 7, RHEL 8, and RHEL 9.0-9.1. It would be preferable if RHEL 9.2 would continue working in the same manner. Perhaps NM managing the loopback device should be only opt-in without the need for opt-out anything. Thanks.
unless you configure a loopback profile in NetworkManager, NM shouldn't do anything with lo.
Please attach the complete journal from the boot, with `level=TRACE` enabled (see DEBUGGING in `man NetworkManager`).
Created attachment 1966388[details]
boot-journal.txt
I'm attaching the output of "/usr/bin/journalctl -b -n 50000 > boot-journal.txt" after booting up a test VM with:
# cat /etc/sysctl.d/50-ipv6.conf
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
# cat /proc/sys/net/ipv6/conf/lo/disable_ipv6
0
Let me know if any additional information is needed. Thanks.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (NetworkManager bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2023:6585
Description of problem: Installing RHEL 9.1, configuring the following sysctls, updating initramfs, and rebooting shows IPv6 being disabled on all interfaces after boot and the sysctl values in use as configured: # cat /etc/sysctl.d/50-ipv6.conf net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1 On the same system upgrading kernel to the latest (currently ~ RHEL 9.2) and rebooting still shows the same results. However, after upgrading NetworkManager to the latest on the same system or doing a fresh RHEL 9.2 installation with the same configuration we see the loopback having IPv6 enabled and the related sysctl changed even when the configuration file sets it to 1: # cat /proc/sys/net/ipv6/conf/lo/disable_ipv6 0 # ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever This procedure of disabling IPv6 is documented in the RHKB article and works on RHEL 7, RHEL 8, and RHEL 9.0-9.1. It would be preferable if RHEL 9.2 would continue working in the same manner. Perhaps NM managing the loopback device should be only opt-in without the need for opt-out anything. Thanks.