[Pkg-utopia-maintainers] Bug#1104061: Bug#1104061: /usr/sbin/NetworkManager: sysctl settings ignored / overriden

[Michael Biebl]

Am 25.04.25 um 09:09 schrieb Benoit Panizzon:
> Package: network-manager
> Version: 1.42.4-1
> Severity: normal
> File: /usr/sbin/NetworkManager
> 
> Dear Maintainer,
> 
> I have been fighting with wrong ipv6 routes for quite a while and have
> finally been able to track them to NetworkManager being the cause. But not
> what exactly in NetworkManager causes the issue.
> 
> I have a system with two ethernet interfaces. One is actually a vxlan interface
> used as a L2 VPN and is set up by some of my scripting.
> 
> In this example, assume eth0 and vxlan1
> 
> I have little control of the ipv6 RA being sent to both interfaces. But for the L2 VPN to
> work as intended, I need the IPv6 default route to point to that interface. So prior to set
> up the vxlan interface I disable accept_ra on eth0 and delete the existing default route:
> 
> ip link add vxlan1 type vxlan id 1 dstport 4789 remote 192.168.10.2
> sysctl -w net.ipv6.conf.eth0.accept_ra_defrtr=0
> sysctl -w net.ipv6.conf.eth0.accept_ra=0

If you are going to manage eth0 manually, why do you want NetworkManager 
to manage eth0 as well?

You can mark a device as unmanaged by NetworkManager

https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html/configuring_and_managing_networking/configuring-networkmanager-to-ignore-certain-devices_configuring-and-managing-networking#permanently-configuring-a-device-as-unmanaged-in-networkmanager_configuring-networkmanager-to-ignore-certain-devices


Aside from that, if you want to have NM manage eth0, you can use the 
ipv6 specific settings

https://www.networkmanager.dev/docs/api/latest/nm-settings-nmcli.html

See ipv6.method and related settings.
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