Discussion during NFWS 2017 in Faro has shown that the current
conntrack behaviour is unreasonable.
Even if conntrack module is loaded on behalf of a single net namespace,
its turned on for all namespaces, which is expensive. Commit
481fa37347 ("netfilter: conntrack: add nf_conntrack_default_on sysctl")
attempted to provide an alternative to the 'default on' behaviour by
adding a sysctl to change it.
However, as Eric points out, the sysctl only becomes available
once the module is loaded, and then its too late.
So we either have to move the sysctl to the core, or, alternatively,
change conntrack to become active only once the rule set requires this.
This does the latter, conntrack is only enabled when a rule needs it.
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This switch (default on) can be used to disable automatic registration
of connection tracking functionality in newly created network
namespaces.
This means that when net namespace goes down (or the tracker protocol
module is unloaded) we *might* have to unregister the hooks.
We can either add another per-netns variable that tells if
the hooks got registered by default, or, alternatively, just call
the protocol _put() function and have the callee deal with a possible
'extra' put() operation that doesn't pair with a get() one.
This uses the latter approach, i.e. a put() without a get has no effect.
Conntrack is still enabled automatically regardless of the new sysctl
setting if the new net namespace requires connection tracking, e.g. when
NAT rules are created.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This entry has been removed in commit 9500507c61.
Fixes: 9500507c61 ("netfilter: conntrack: remove timer from ecache extension")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
No need to restrict this to module parameter.
We export a copy of the real hash size -- when user alters the value we
allocate the new table, copy entries etc before we update the real size
to the requested one.
This is also needed because the real size is used by concurrent readers
and cannot be changed without synchronizing the conntrack generation
seqcnt.
We only allow changing this value from the initial net namespace.
Tested using http-client-benchmark vs. httpterm with concurrent
while true;do
echo $RANDOM > /proc/sys/net/netfilter/nf_conntrack_buckets
done
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Manually bumping either nf_conntrack_buckets or nf_conntrack_max has
become a common task as our Linux servers tend to serve more and more
clients/applications, so let's adjust nf_conntrack_buckets this to a
more updated value.
Now for systems with more than 4GB of memory, nf_conntrack_buckets
becomes 65536 instead of 16384, resulting in nf_conntrack_max=256k
entries.
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
I grepped through the code and picked bits about nf_conntrack sysctl api
and put that into one documentation file.
[ I have mangled this patch including comments from several grammar
improvements proposed by Neal Murphy <neal.p.murphy@alum.wpi.edu>,
any new grammar error is my mistake --pablo ]
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Florian Westphal