[LARTC] Re: iptables diagram (ex: ipchains + mark in output chain ?)

[Julian Anastasov <ja@ssi.bg>]

	Hello,

On Tue, 18 Jun 2002, Ciprian Niculescu wrote:

> so you say that are 3 routing decision:
> - after nat prerouting
> - after local_process, and before mangle output
> - before nat postrouting

	Basicly, there are 2 routing decisions, for the others
I like the name rerouting:

1. Input Routing: after prerouting, kernel performs source
validation and nexthop decision, result: local_deliver/forwarding

2. Output Routing: local_process selects source address, creates
connected route or selects route for each packet. The resolved
route is attached to the packet and is used later. The Netfilter's
LOCAL_OUT chain detects complete packet which is obviously loaded with
some addresses. Which ones do you think if routing _decision_ is
not performed? :)

3. Output Rerouting: netfilter at LOCAL_OUT changes the already
selected output route if any of the routing keys are changed:
addresses, tos, nfmark, etc. The intention is the packet to change
its attached route and probably to go in another direction.
The connected sockets do not notice this change, they remain
connected to the initial route.

> what is the use of the routing decision after local process???

see 2.

	Note also that after FORWARD there is no routing
decision :)))

	I'll not iterate this issue anymore. We already disturb
the LARTC subscribers :)

Regards

--
Julian Anastasov <ja@ssi.bg>

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