Hi

Here is scheme of my home network:

Internet
|
|
Cable modem
|
|
82.147.170.110
eth1
|
Computer with Ubuntu
|
eth0
192.168.0.1
|
|
|
192.168.0.2
Computer with Windows Xp

Heres my ifconfig:

eth0 Link encap:Ethernet HWaddr 00:08:A1:7D:79:20
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::208:a1ff:fe7d:7920/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:47 dropped:0 overruns:0 carrier:47
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:12 Base address:0xd400

eth1 Link encap:Ethernet HWaddr 00:C0:26:76:9F:CB
inet addr:82.147.170.110 Bcast:82.147.170.255 Mask:255.255.255.0
inet6 addr: fe80::2c0:26ff:fe76:9fcb/64 Scope:Link
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:620658 errors:0 dropped:0 overruns:0 frame:0
TX packets:595653 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:570941271 (544.4 MiB) TX bytes:38344191 (36.5 MiB)
Interrupt:12 Base address:0xd000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:262309 errors:0 dropped:0 overruns:0 frame:0
TX packets:262309 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:19519510 (18.6 MiB) TX bytes:19519510 (18.6 MiB)


When I boot up computer with 2 nics in Windows Xp instead of Ubuntu, then sharing Internet works perfectly. When I boot up in Ubuntu, then I can't even ping from Computer_2 to Computer_1 and vice versa. I believe I have to get these both computers talk before doing any masquerading right? If so, how?

Perhaps you have the modules loaded in the wrong order so that what you believe is eth0 is really eth1? If you plug the internal network cable into the other nic (that currently goes to your cable modem), perhaps the ping works? Then you'd need to change the sequence how the modules load, or re-assign their roles in the network setup. If you need to maintain the status for your windows setup, the modules setting is the right way.

Hope it helps,
mlp

It didn't make any difference when I changed cables between nic's - I still couldn't reach 192.168.0.2. After that I tried swiching my logic configurations of both nic's - eth0 with eth1 configurations and vice versa. Now I couldn't activate my nic with external IP and still could not ping other machine with internal IP. I even tried different combinations of ping -I eth0 192.168.0.2 and ping -I eth1 192.168.0.2.

Something must be very wrong

Code:

eth0 Link encap:Ethernet HWaddr 00:08:A1:7D:79:20
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::208:a1ff:fe7d:7920/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:47 dropped:0 overruns:0 carrier:47
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:12 Base address:0xd400

Your internal interface has no TX/RX packets, just carrier errors. Carrier errors can usually be associated with a bad patch cable or even speed/duplex mismatch of the NIC. I would think having the wrong NIC driver loaded could also cause these types of errors.

most probable reasons
1) wrong drivers
2) wrong config files
3) bad cables (which is ruled out since ur Win Xp works on the same machine)
4) bad routing...

So for bad drivers check this...
#>lspci <-- this will give you the pci cards details... figure out your ethernet cards..
#>lsmod <-- this will give you loaded modules... just check if the modules are OK for the probed cards

If not..
find the modules for them under /lib/modules/`uname -r`/kernel/drivers/net...

and if u are lucky u will locate a suitable driver...
so rm the unwanted module by..
#> rmmod 'badmodule'
load the OK module
#> insmod 'okmodule'

try restart the network..

and in case if you have bad config files... read the networking docs

$ lspci
0000:00:00.0 Host bridge: Silicon Integrated Systems [SiS] SiS645 Host & Memory & AGP Controller (rev 01)
0000:00:01.0 PCI bridge: Silicon Integrated Systems [SiS] Virtual PCI-to-PCI bridge (AGP)
0000:00:02.0 ISA bridge: Silicon Integrated Systems [SiS] SiS961 [MuTIOL Media IO]
0000:00:02.1 SMBus: Silicon Integrated Systems [SiS]: Unknown device 0016
0000:00:02.2 USB Controller: Silicon Integrated Systems [SiS] USB 1.0 Controller (rev 07)
0000:00:02.3 USB Controller: Silicon Integrated Systems [SiS] USB 1.0 Controller (rev 07)
0000:00:02.5 IDE interface: Silicon Integrated Systems [SiS] 5513 [IDE] (rev d0)0000:00:02.7 Multimedia audio controller: Silicon Integrated Systems [SiS] Sound Controller (rev a0)
0000:00:09.0 Ethernet controller: Davicom Semiconductor, Inc. 21x4x DEC-Tulip compatible 10/100 Ethernet (rev 40)
0000:00:0a.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
0000:01:00.0 VGA compatible controller: nVidia Corporation NV11 [GeForce2 MX/MX 400] (rev b2)

$ lsmod
Module Size Used by
isofs 33720 1
udf 77060 0
proc_intf 4100 0
freq_table 4100 0
cpufreq_userspace 4572 0
cpufreq_ondemand 6172 0
cpufreq_powersave 1920 0
video 16260 0
sony_acpi 6280 0
pcc_acpi 11264 0
button 6800 0
battery 10244 0
container 4608 0
ac 4996 0
ipv6 229504 15
af_packet 20744 2
8139cp 19200 0
8139too 24320 0
mii 4736 2 8139cp,8139too
dmfe 18716 0
tulip 46112 0
snd_intel8x0 29984 1
snd_ac97_codec 64608 1 snd_intel8x0
snd_pcm_oss 47652 0
snd_mixer_oss 16768 2 snd_pcm_oss
snd_pcm 84872 3 snd_intel8x0,snd_ac97_codec,snd_pcm_oss
snd_timer 23300 1 snd_pcm
snd 50276 6 snd_intel8x0,snd_ac97_codec,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_timer
soundcore 9824 2 snd
snd_page_alloc 9604 2 snd_intel8x0,snd_pcm
tsdev 7488 0
usbhid 29376 0
ohci_hcd 19848 0
usbcore 107384 3 usbhid,ohci_hcd
i2c_sis96x 5380 0
i2c_core 21264 1 i2c_sis96x
shpchp 86116 0
pci_hotplug 30512 1 shpchp
sis_agp 8068 1
agpgart 31784 1 sis_agp
analog 10784 0
gameport 4608 1 analog
floppy 54864 0
pcspkr 3816 0
rtc 12216 0
nls_cp437 5888 2
ntfs 97136 1
md 43856 0
dm_mod 53116 1
capability 5000 0
commoncap 7808 1 capability
parport_pc 34372 1
lp 10792 0
parport 33480 2 parport_pc,lp
evdev 9088 0
ide_cd 38532 1
cdrom 36508 1 ide_cd
mousedev 11160 1
psmouse 19336 0
ext3 120968 1
jbd 54168 1 ext3
ide_generic 1664 0
sis5513 15112 1
ide_disk 18176 4
ide_core 118988 4 ide_cd,ide_generic,sis5513,ide_disk
unix 26164 843
thermal 13576 0
processor 22708 1 thermal
fan 4612 0
fbcon 34048 0
font 8448 1 fbcon
bitblit 5120 1 fbcon
vesafb 6948 0
cfbcopyarea 3968 1 vesafb
cfbimgblt 3072 1 vesafb
cfbfillrect 3584 1 vesafb

I think my both nic cards are properly installed. Am I wrong?

yes...
seems like you nic are proparly installed..
now I think you have bad configs...
check the ifcfg-eth0 and ifcfg-eth1...
also you can check the default route...
ip route list

ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:08:A1:7D:79:20
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::208:a1ff:fe7d:7920/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:5 dropped:0 overruns:0 carrier:5
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:12 Base address:0xd400

ifconfig eth1
eth1 Link encap:Ethernet HWaddr 00:C0:26:76:9F:CB
inet addr:82.147.170.110 Bcast:82.147.170.255 Mask:255.255.255.0
inet6 addr: fe80::2c0:26ff:fe76:9fcb/64 Scope:Link
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:15793 errors:0 dropped:0 overruns:0 frame:0
TX packets:2676 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2594461 (2.4 MiB) TX bytes:420400 (410.5 KiB)
Interrupt:12 Base address:0xd000

ip route list
82.147.170.0/24 dev eth1 proto kernel scope link src 82.147.170.110
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1
default via 82.147.170.1 dev eth1

anyone?

I guess I can never make this work

Is the 2nd XP PC configured for a static or dynamic IP address? I suggest using a static IP address on the 2nd PC to eliminate DHCP problems.

If you have DHCP running on ubuntu does the 2nd PC network card get an IP address?

If running a firewall on ubuntu then make sure to accept all traffic on eth0.

2nd Nic has been configured as static not DHCP and on windows box its static aswell

Can you ping successfully from windows to ubuntu yet?
Have you disabled the firewall if it is running?

No i can't ping from windows box and I haven't installed any firewalls, unless ubuntu hasn't installed it by default

It seems like you have other problems, too, but I thought I would ask if you have ip-forwarding turned on in Ubuntu. By default, it is turned off.

You can check with
and set it with