This is meant to replace /proc/sys/net/ipv4/conf/*/rp_filter, which
only works for ipv4. Furthermore, it's nicer to handle this kind of
filtering in the firewall.
There are some more subtle differences, please see:
https://home.regit.org/netfilter-en/secure-use-of-helpers/
I chose to enable this by default (when the firewall is enabled) as
it's a good idea in general. Only people with advanced routing needs
might not want this, but I guess they don't use the nixos firewall
anyway and use a custom solution. Furthermore, the option only becomes
available in kernel 3.3+, so conservative nixos users that just stick
to the default kernel will not need to act now just yet.
The triggers are just arbitrary strings that are included in the unit
under X-Restart-Triggers. The idea is that if they change between
reconfigurations, switch-to-configuration will restart the unit
because its store path changed. This is mostly useful for services
that implicitly depend on generated files in /etc. Thus you can say
restartTriggers = [ confFile ];
where ‘confFile’ is the derivation that generated the /etc file in
question.
Flushing is bad if the Nix store is on a remote filesystem accessed
over that interface.
http://hydra.nixos.org/build/3184162
Also added a interface option ‘prefixLength’ as a better alternative
to ‘subnetMask’.
Instead it's enough to depend on
sys-subsystem-net-devices-<interface>.device, which in turn has a
"wants" dependency on the service (if any) that creates the interface.
For each statically configured interface, we now create a unit
‘<interface>-cfg.service’ which gets started as soon as the network
device comes up. Similarly, each bridge defined in
‘networking.bridges’ and virtual interface in ‘networking.interfaces’
is created by a service ‘<interface>.service’.
So if we have
networking.bridges.br0.interfaces = [ "eth0" "eth1" ];
networking.interfaces =
[ { name = "br0";
ipAddress = "192.168.1.1";
}
];
then there will be a unit ‘br0.service’ that depends on
‘sys-subsystem-net-devices-eth0.device’ and
‘sys-subsystem-net-devices-eth1.device’, and a unit ‘br0-cfg.service’
that depends on ‘sys-subsystem-net-devices-br0.device’.
The special handling for cronjobs should probably move to the cron
module (logcheckIgnore = bool option) in the future, as it's more
natural to just declare a cronjob, and mark it as "log-ignored",
instead of adding cronjobs through logcheck.
But as systemCronjobs is not an attrset yet (just simple strings),
this would require adding an attrset for cronjobs or parsing strings
in the nix language to get hold of the cron-user and command.
So for now, I keep the interface within logcheck's module.
However SLIM is still broken and you have to create a
/usr/lib/dri/fglrx_dri.so symlink pointing to
/run/opengl-driver/lib/fglrx_dri.so
At least fgl_glxgears shows 10 times more frames per second now
This is broken because it requires restarting applications to see new
NSS modules. The proper way to handle NSS modules is through nscd.
See commit 554ae9908b4abd45c9769da023470ae2c12ebdfd.
