[LARTC] A complicated routing scenario (for me at least)

[Andrew andrewd@uccsda.org]

<PRE>Greetings:

I've been pouring over every piece of documentaiton on the subject I can
find, and I've concluded that advanced routing + ipchains is what I
need. It also appears that the people that can answer some of the more
in depth questions I have, read this list.

I'm fairly new to this so please forgive me if I ask stupid questions.
Anyway.

Here is what I'm trying to accomplish in ASCII art:

                                 LAN
                                  | (172...)
                                  |
         _/\__/\_             +---+----+            _/\__/\_
        /        \   (63...)  |        | (204...)  /        \
       ( Internet )-----------+ Router +----------( Internet )
        \_  __  _/            |        |           \_  __  _/
          \/  \/              +----+---+             \/  \/ 
                                   | 63..
                                   | 204..
                                   |
                 --+---------------+----------+--  &lt;---single physical
net
                   |                          |        (i.e. one hub)
                   |                          |
               +---+---+ 63..1            +---+---+ 63..2
               | Linux | 63..4            | Linux | 63..3
               +-------+ 204..1           +-------+ 204..2
                         204..4                     204..3

The desired end result is a redundant connection to two dns/mail servers
from the 
internet. I'm willing to fight through this, but I have a few specific
question's 
for now that I'm hoping someone can answer.

1. From a server's perspective, do incoming packets get responded to on
the same interface they came in on? Does it matter if the interface in
question is an alias?

2. if I tag a packet coming into the router/firwall above with ipchains
for routing purposes, will the tag persist to the reply packets? Or do I
have to tag the reply packets with ipchains from the responding server?

3. In reading the various documentation, I noticed several references to
files in the /etc/iproute2 directory. Related to this directory:
	a) is there any documentation on the names and syntax of the various
files other than the source code, and the casual references I've found?
	b) I don't currently have this directory in /etc. Is it something I
just create, and does it's existance imply that the kernel will read
configureation data from it on boot?

Incidentally I'm currently using kernel 2.2.17 on my boxes. Since I'm
already going to be meticulously documenting my setup, I'd be willing to
do so in a format that could be posted as a HOWTO or as an example in
someone else's HOWTO, whatever would be most usefull.

Suggestions in this area are much appreciated since I have no experiance
in HOWTO writing. (Plenty of writing experiance, just not howtos)

Anyway, Thanks for the help.

-Andrew


</PRE>