My main reason for adding this is the ability to turn off helpers
altogether. If you are not using any of the special protocols, keeping
them turned off is safest, and in case you do want to use them, it's
best to configure them through the new CT target for your network
topology. Perhaps some sane defaults for nixos can be examined in the
future.
This change has no impact if you don't touch the added options, so no
need to adapt.
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.
should make it easier to compose with packages that set their own
firewall rules, such as Nova or Libvirt.
* Provide a chain for accepted packets (‘nixos-fw-accept’), requested
by Nicolas Pierron.
svn path=/nixos/trunk/; revision=27607
for (apparently) open TCP connections that connection tracking
doesn't know about. This prevents TCP connections to this machine
from hanging in CLOSE_WAIT for a long time.
svn path=/nixos/trunk/; revision=26802
* Firewall: change the policy of the INPUT chain back to ACCEPT to
prevent a lockup when the Nix store is mounted over the network
(i.e. in our VM tests). This is because as soon as the policy is
set to DROP, the iptables modules that enable access to the network
filesystem cannot be acccessed anymore.
svn path=/nixos/trunk/; revision=26274
