[SOLVED] IP forwarding with ppp0

getdev · 12-31-2011, 04:42 AM

Hello, after problems on my linksys modem-router (it is KO), I try to connect my private network with my old speed touch home ethernet.

Here problems starts.

I have a server slackware with 3 ethernet cards.

eth0 (192.168.2.2) : connected to hub and is server dhcp for 192.168.2.0/24
eth1 -> pppoe
eth2 (192.168.1.2) : connected to my computer and is also server dhcp for 192.168.1.0/24

My computer get an IPv4 address without problem, but it can't go on internet.

My iptables script is :

Code:

# iptables rules
/usr/sbin/iptables -A POSTROUTING -t nat -o ppp0 -j MASQUERADE
echo "1" > /proc/sys/net/ipv4/ip_forward

but my PC don't join internet and no log appears in /var/log/syslog nor /var/log/messages on my server.

By searching here I found that link :
http://www.akadia.com/services/pppoe_iptables.html

My pppoe.conf file seems Ok :
...
DEFAULTROUTE=yes
...
CLAMPMSS=1412
...

But when I type :

Code:

# netstat -nr
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
90.12.193.1     0.0.0.0         255.255.255.255 UH        0 0          0 ppp0
192.168.2.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth2
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
0.0.0.0         0.0.0.0         0.0.0.0         U         0 0          0 ppp0

The last route for ppp0 is not set as UG (for gateway) so I del this one and recreate :

Code:

# route del default
# route add default gw 90.12.193.1
# netstat -nr
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
90.12.193.1     0.0.0.0         255.255.255.255 UH        0 0          0 ppp0
192.168.2.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth2
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
0.0.0.0         90.12.193.1     0.0.0.0         UG        0 0          0 ppp0

But I still can't access to the net with my PC

slacware 13.0
Roaring Penguin PPPoE Version 3.10
iptables v1.4.3.2

getdev · 01-02-2012, 07:36 AM

I had tried with this lines on my server :

Code:

/usr/sbin/iptables -A POSTROUTING -t nat -o ppp0 -j MASQUERADE
echo "1" > /proc/sys/net/ipv4/ip_forward
/sbin/sysctl -w net.ipv4.ip_forward=1

With the last line I now can access internet. But while on my server DNS is OK, it don't work from my PC.

Using traceroute with a google IP :

Code:

# traceroute 173.194.66.147
traceroute to 173.194.66.147 (173.194.66.147), 30 hops max, 60 byte packets
 1  192.168.1.2 (192.168.1.2)  0.450 ms  0.459 ms  0.318 ms
...
11  * * *
12  173.194.66.147 (173.194.66.147)  49.047 ms  50.011 ms  48.229 ms

with DNS :

Code:

# traceroute www.google.fr
www.google.fr: Nom ou service inconnu
Cannot handle "host" cmdline arg `www.google.fr' on position 1 (argc 1)

I'm close to the end I think, but it still not work.

getdev · 01-04-2012, 08:10 AM

I have added my provider DNS to the DNs configuration for my DHCP and it work.
It's not exactly the way I want, but I'm looking for a new modem-router so I will modify rules after having my new modem.