Hi

I have two computers

Here is my network configuration of the main one:
eth0: external network (DHCP ip)
eth1: internal (192.168.0.1)

I have another computer connected by cross cable to eth1 with ip 192.168.0.2
Each computer can "ping" (communicate) each other

Then I set up a Nat server at the main computer , I run these scripts at startup

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.0.0/24 -j MASQUERADE
dnsmasq

Then here is the problem, I can't connect to network on the second computer.


Main system configuration
Kernel: 2.6.26
Distro: Linuxfromscratch
Modules list:

Module Size Used by
ipt_MASQUERADE 3136 1
iptable_nat 6224 1
nf_nat 18128 2 ipt_MASQUERADE,iptable_nat
nf_conntrack_ipv4 15448 3 iptable_nat,nf_nat
nf_conntrack 56256 4 ipt_MASQUERADE,iptable_nat,nf_nat,nf_conntrack_ipv4
ip_tables 17232 1 iptable_nat
x_tables 19016 3 ipt_MASQUERADE,iptable_nat,ip_tables
saa7134_alsa 12256 0
snd_hda_intel 343508 0
snd_pcm 69004 2 saa7134_alsa,snd_hda_intel
snd_timer 21000 1 snd_pcm
snd_page_alloc 8720 2 snd_hda_intel,snd_pcm
snd_hwdep 8456 1 snd_hda_intel
snd 59848 5 saa7134_alsa,snd_hda_intel,snd_pcm,snd_timer,snd_hwdep
soundcore 6880 1 snd
fglrx 2019532 25
tuner 27532 0
tea5767 7108 1 tuner
tda8290 14084 1 tuner
tuner_xc2028 21872 1 tuner
xc5000 11716 1 tuner
tda9887 11140 1 tuner
tuner_simple 15188 1 tuner
tuner_types 17472 1 tuner_simple
mt20xx 13384 1 tuner
tea5761 5188 1 tuner
saa7134 153564 1 saa7134_alsa
compat_ioctl32 9216 1 saa7134
videodev 32192 3 tuner,saa7134,compat_ioctl32
v4l1_compat 16004 1 videodev
v4l2_common 11520 2 tuner,saa7134
videobuf_dma_sg 11908 2 saa7134_alsa,saa7134
videobuf_core 17412 2 saa7134,videobuf_dma_sg
ir_kbd_i2c 9552 1 saa7134
ir_common 37316 2 saa7134,ir_kbd_i2c
tveeprom 14852 1 saa7134
r8169 27204 0
3c59x 43764 0
mii 5312 1 3c59x
unix 26288 34


Is there something wrong with the modules or the scripts?

Does this computer get its IP from DHCP (i.e. from dnsmasq on PC 1 ) ? If so it should automatically set it's default gateway to the IP of PC1 (192.168.0.1). You can check this with the route command on PC2.

Also check your /etc/dnsmasq.conf to make sure it's setup correctly for DHCP if thats what your going for.

If you are assigning a static IP on PC2 you will have to set the default gateway to be 192.168.1.1 yourself with route (along with DNS name server entries in /etc/resolv.conf). You may of course have dnsmasq give out a static IP to PC2 by setting up /etc/dnsmasq.conf to always pass out a particular ip to its Mac address.

Thank you bgeddy !!

It seems that I need to set the route on PC2

I do:
ip route add default via 192.168.0.1

Then it works

Thanks for reminding me!