Masq/Sharing 2 Internet connections

From: AcCeSsDeNiEd (dillon_at_SpamMinuSaccessdenied.darktech.org)
Date: 08/14/04 

Date: Sat, 14 Aug 2004 18:30:20 +0800

I'm pulling my hair out getting this one to work.

So anyone out there plz help.

I have this setup:

                                                                 ________
                                          +------------+ /
                                          | | |
                            +-------------+ Provider 1 +-------
        __ | | | /
    ___/ \_ eth0 +------+-------+ +------------+ |
  _/ \__ -----| eth2 | /
 / | | |
| Local network + Linux router | | Internet
 \_ eth1 | | |
   \__ __/ -----| ppp0 | \
      \___/ +------+-------+ +------------+ |
                            | | | \
                            +-------------+ Provider 2 +-------
                                          | | |
                                          +------------+ \________

eth0 and eth1 are connected to my Local area network:

eth0=10.30.1.0
eth1=10.20.0.0

eth2 is connected to the internet via a lease line.
ppp0 is connected to an ADSL provider:

eth2=161.18.195.4
ppp0=220.255.206.242

I need the users on eth0 to access the internet via eth2 and
          the users at eth1 should access the internet via ppp0

I read the Linux Advance networking at: http://www.lartc.org/howto/lartc.rpdb.multiple-links.html
And this is what I did:

Added tables 'IPQ_eth2' and 'ADSL' in /etc/iproute2/rt_tables

eth2:
#/sbin/ip route add 161.18.195.0 dev eth2 src 161.18.195.4 table IPQ_eth2
#/sbin/ip route add default via 161.18.195.1 table IPQ_eth2
#/sbin/ip route add 161.18.195.0 dev eth2 src 61.8.195.4
#/sbin/ip rule add from 161.18.195.4 table IPQ_eth2

ppp0:
#/sbin/ip route add 220.255.206.0 dev ppp0 src 220.255.206.242 table ADSL
#/sbin/ip route add default via 220.255.206.1 table ADSL
#/sbin/ip route add 220.255.206.0 dev ppp0 src 220.255.206.242
#/sbin/ip rule add from 220.255.206.242 table ADSL

Ok, from here on, packets coming into the Internet connections get out/back via their own respective
gateways. That works.

Next to share the internet connections:
In my IPTABLES:

#Enable NAT routing from eth2
$IPT -t nat -A POSTROUTING -o eth2 -s 10.30.1.0/24 -j MASQUERADE

#Enable NAT routing from ppp0 (ADSL)
$IPT -t nat -A POSTROUTING -o ppp0 -s 10.20.0.0/22 -j MASQUERADE

This is where the problem is. Only the ppp0 sharing works with the eth1 users.
That is, if I don't set a default gateway on the linux box.
Setting a default gateway (161.18.195.1) in ifcfg-eth2 has reverse results.
I can only get either one sharing to work but not both.

What am I missing?
Thanks a million.

To e-mail, remove the obvious

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