Adds a new chain in the raw table for reverse path filtering and optional
logging. A rule to allow serving DHCPv4 was also added as it is commonly
needed and poses no security risk even when no DHCPv4 server is running.
Fixes#10101.
This patch fixes https://github.com/NixOS/nixpkgs/issues/12927.
It would be great to configure good rate-limiting defaults for this via
/proc/sys/net/ipv4/icmp_ratelimit and /proc/sys/net/ipv6/icmp/ratelimit,
too, but I didn't since I don't know what a "good default" would be.
- add missing types in module definitions
- add missing 'defaultText' in module definitions
- wrap example with 'literalExample' where necessary in module definitions
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
This prevents errors like "Another app is currently holding the
xtables lock" if the firewall and NAT services are starting in
parallel. (Longer term, we should probably move to a single service
for managing the iptables rules.)
This is useful for packages like mosh, which use a wide UDP port range
by default for incoming connections.
Signed-off-by: Austin Seipp <aseipp@pobox.com>
