GNOME Bugzilla – Bug 710858
NetworkManager controlled bridge overrides sysctl.d netfilter settings
Last modified: 2020-11-12 14:32:13 UTC
Using nm controlled bridge, with sysctl.conf containing: net.bridge.bridge-nf-call-ip6tables = 0 net.bridge.bridge-nf-call-iptables = 0 net.bridge.bridge-nf-call-arptables = 0 After a reboot, all these have been set to 1. This then stops, for example, DHCP from working on virtual machines using the "shared physical device" setup Version-Release number of selected component (if applicable): NetworkManager-0.9.9.0-14.git20131003.fc20.x86_64 Seen on Fedora 20:https://bugzilla.redhat.com/show_bug.cgi?id=1022977
I'm not aware of overriding them explicitly... maybe a kernel issue? Will need more investigation. Thank you for your report.
The main reason I am waving my finger in the direction of NM is that this box has been working as a virtual machine host since it was built. Because of previous issues with NM, it was configured with the standard "network" service, with NM disabled. The box has recently been upgraded to F20, which advertises NM control for network bridges. As such, I disabled the network service, and enabled NetworkManager to try it out. NM correctly picks up all the existing configuration for the bridge, and reports it correctly through the user interface. However, my virtual machines couldn't get DHCP requests out. After considerable messing around, I discovered that these bridge netfilter settings had been overridden. Disabling network manager and re-enabling network cures the issue. Workaround is to create /etc/NetworkManager/dispatcher.d/00-sysctl with the following: #!/bin/sh /usr/lib/systemd/systemd-sysctl exit 0
As I wrote in https://bugzilla.redhat.com/show_bug.cgi?id=1022977, this might be a generic systemd / system initialiation problem rather than a NetworkManager bug.
bugzilla.gnome.org is being shut down in favor of a GitLab instance. We are closing all old bug reports and feature requests in GNOME Bugzilla which have not seen updates for a long time. If you still use NetworkManager and if you still see this bug / want this feature in a recent and supported version of NetworkManager, then please feel free to report it at https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/ Thank you for creating this report and we are sorry it could not be implemented (workforce and time is unfortunately limited).