Currently, every time the iptables controller syncs rules, it spawns an
an iptables process for every rule it checks. This causes two problems:
1. it creates unnecessary load on the system; and
2. it causes contention on the xtables lock file.
This commit creates a lazy cache for iptables rules and chains that
avoids spawning iptables processes. This means that each time the
iptables rules are reconciled, if no rules need to be changed then at
most one iptables process should be spawned to check all of the rules in
a chain and at most one process should be spawned to check all of the
chains in a table.
Note: the success of this reduction in calls to iptables depends on a
somewhat fragile comparison of iptables rule text. The text of any rule
must match exactly, including the order of the flags. An improvement to
come would be to implement an iptables rule parser than can be used to
check semantic equivalence betweem iptables rules.
Signed-off-by: Lucas Servén Marín <lserven@gmail.com>
This commit enables simultaneously managing IPv4 and IPv6 iptables
rules. This makes it possible to have peers with IPv6 allowed IPs in an
otherwise IPv4 stack and vice versa.
Signed-off-by: Lucas Servén Marín <lserven@gmail.com>
This commit cleans up the iptables package to allow other packages to
create rules.
This commit also removes all NAT from Kilo.
Signed-off-by: Lucas Servén Marín <lserven@gmail.com>
This commit takes a big step towards ensuring that iptables rules are
always kept in the correct order. Specifically, when re-setting a a
ruleset, any time a rule is missing, that rule and all following rules
are re-added to ensure that from that index onwards all rules are in the
right order. Similarly, when reconciling an existing ruleset against the
backend, if a rule is missing, that rule an all following rules are
re-added.
This change does not guarantee that the order of rules in the backend
is correct. Unless an actor is modifying the order of rules in iptables,
all rules created by Kilo should now be kept in the correct order.
Fixes: #19
Lucas Servén Marín