Pablo Neira Ayuso wrote:
Patrick McHardy wrote:
ip maddr add 01:00:5e:00:01:01 dev eth1
ip maddr add 01:00:5e:00:01:02 dev eth2
arptables -I OUTPUT -o eth1 --h-length 6 \
-j mangle --mangle-mac-s 01:00:5e:00:01:01
arptables -I INPUT -i eth1 --h-length 6 \
--destination-mac 01:00:5e:00:01:01 \
-j mangle --mangle-mac-d 00:zz:yy:xx:5a:27
Mhh, is the saving of one or two characters really worth these
deviations from the kind-of established naming scheme? Its hard
to remember all these minor differences in my opinion.
Hm, you mean the name "mangle" or the name of the option
"--mangle-mac-d"? This is what we currently have in kernel mainline and
arptables userspace, it's not my fault :). I can send you a patch to fix
it with a consistent naming without breaking backward compatibility both
in kernel and user-space.
Great, I wasn't aware that this already existed in userspace :)
In the case of TCP connections, pickup facility has to be disabled
to avoid marking TCP ACK packets coming in the reply direction as
valid.
echo 0 > /proc/sys/net/netfilter/nf_conntrack_tcp_loose
I'm not sure I understand this. You *don't* want to mark them
as valid, and you need to disable pickup for this?
If TCP pickup is enabled, one TCP ACK packet coming in the reply
direction enters TCP ESTABLISHED state. Since that's a valid
state-transition, the cluster match will consider that this is part of a
connection that this node is handling since it's a valid
state-transition. The cluster match does not mark packets that trigger
invalid state transitions.
Why use conntrack at all? Shouldn't the cluster match simply
filter out all packets not for this cluster and thats it?
You stated it needs conntrack to get a constant tuple, but I
don't see why the conntrack tuple would differ from the data
that you can gather from the packet headers.
echo +2 > /proc/sys/net/netfilter/cluster/$PROC_NAME
Does this provide anything you can't do by replacing the rule
itself?
Yes, the nodes in the cluster are identifies by an ID, the rule allows
you to specify one ID. Say you have two cluster nodes, one with ID 1,
and the other with ID 2. If the cluster node with ID 1 goes down, you
can echo +1 to node with ID 2 so that it will handle packets going to
node with ID 1 and ID 2. Of course, you need conntrackd to allow node ID
2 recover the filtering.
I see. That kind of makes sense, but if you're running a
synchronization daemon anyways, you might as well renumber
all nodes so you still have proper balancing, right?
Now, I see that there is a possible optimization that consists of
checking if one node has its node mask all set with regards to the total
number of nodes, so that hashing can be skipped. But that's something
that we can add later I think.
Indeed.
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
