Hi everyone,

I am trying to share an internet connection with a Windows XP System. My linux system has the following specs...

Fedora Core 5
2 Network Cards...
eth0 192.168.1.5 Connected to router.
eth1 192.168.1.50 Connected to the Windows System
Gateway 192.168.1.1

XP System 192.168.1.6

The problem is that I cannot get my system to ping the XP system. It is not a network problem - if I boot to windows, I can easily access the shares on the other system.

The ping shows this...
PING 192.168.1.6 (192.168.1.6) 56(84) bytes of data.
From 192.168.1.5 icmp_seq=1 Destination Host Unreachable

The 'From' part is wrong - 192.168.1.5 is connected to the router. 192.168.1.50 is the card that is connected to the XP system.

I cannot ping 192.168.1.50 from the windows system as well.

Any ideas?

If you need any more data from my side, let me know.

You cannot use 192.168.1.xxx to both interface on linux machine. Either change your router side or windows side ip range to 192.168.0.xxx.

I tried this - now
eth1 is 192.168.0.50
xp is 192.168.0.6

I still cannot ping one computer from the other. What are th possible explanations for this behavior?

Do you have the Windows firewall enabled on the XP system?

I have disabled all firewalls on the windows system.

If I boot my system into XP too(leaving the other system on XP) I can ping the other system. The ip is the same on windows too(192.168.0.50).

If you need any info from my side, just ask.

Hmm that is very odd, so you have assigned IP addresses in the same range and subnet as the Windows machine, but still cannot ping the Windows machine?

Can you paste a copy of your ipconfig /all and ifconfig from your windows/linux systems respectively in here? I take it you have no problem pinging the gateway IP from the Linux box, and pinging the other NICs (other eth in the Linux box) IP?

Thanks for the help, guys. Here is the requested info

Windows XP : ipconfig /all
--------------------------
Windows IP Configuration

Host Name . . . . . . . . . . . . : bijoy
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : NVIDIA nForce MCP Networking Adapter
Physical Address. . . . . . . . . : 00-11-2F-50-5C-B9
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.0.6
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :
DNS Servers . . . . . . . . . . . : 203.197.12.42
202.54.6.60

===========================================================================
Linux : ifconfig
----------------
eth0 Link encap:Ethernet HWaddr 00:134:F1:79:7B
inet addr:192.168.1.5 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::213:d4ff:fef1:797b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:203 errors:0 dropped:0 overruns:0 frame:0
TX packets:60 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:42023 (41.0 KiB) TX bytes:5176 (5.0 KiB)
Interrupt:17 Base address:0x2000

eth1 Link encap:Ethernet HWaddr 00:08:A1:7B:BB:41
inet addr:192.168.0.50 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::208:a1ff:fe7b:bb41/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:2 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:150 (150.0 b)
Interrupt:18 Base address:0x6000

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:982 errors:0 dropped:0 overruns:0 frame:0
TX packets:982 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1743664 (1.6 MiB) TX bytes:1743664 (1.6 MiB)

===========================================================================
Another thing that I forgot to mention - when I am activating the eth1 lan card on Linux, I get this message

Message from syslogd@localhost at Thu Nov 23 22:34:50 2006 ...
localhost kernel: Disabling IRQ #18

Could it be responsible somehow?

No problems there.

ping 192.168.1.1
ping 192.168.1.5
ping 192.168.0.50
all works fine.

Possibly, sorry I dont have time for a concise answer! (Going somewhere in a bit)

But you can find out easily by doing this:

ifconfig eth1 down

Swap the CAT5/6 cables over so eth0 is now eth1 and vice versa (cable wise)

ifconfig eth0 up 192.168.0.50 255.255.255.0

ping 192.168.0.6

Hope that helps, if only somewhat!

Ping Works - but the problem is not over yet

When I ran
ifconfig eth0 up 192.168.0.50 255.255.255.0

I got this error...
SIOCSIFADDR: Invalid argument

What does this mean?

When this failed, I used the GUI tool system-config-network to change the IP and did a 'service network restart'

Now, ipconfig eth0 outputs this...

eth0 Link encap:Ethernet HWaddr 00:134:F1:79:7B
inet addr:192.168.0.50 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:3139 errors:0 dropped:0 overruns:0 frame:0
TX packets:3027 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2105649 (2.0 MiB) TX bytes:588131 (574.3 KiB)
Interrupt:17 Base address:0x2000

Now I can ping the XP system and it can ping me. :-D

Any ideas why it works now - and not the other way around?

But when I tried to open a browser with my ip 192.168.0.50 from the XP system, it showed a 'Cannot connect' error. This should not happen as I am running an apache server on the FC5 system and can access it from this system.

After that, I tried to reconfigure my eth1 so that I could access the net. I gave it the ip 192.168.1.5 and set the gateway accodingly.

ifconfig eth1 :
---------------
eth1 Link encap:Ethernet HWaddr 00:08:A1:7B:BB:41
inet addr:192.168.1.5 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::208:a1ff:fe7b:bb41/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:768 (768.0 b)
Interrupt:18 Base address:0x6000

Now I cannot ping the router. I don't think this is the problem of the card, as I can access the network using that card in windows. There is very little problems then.

However, the message I talked about earlier still pops up when I 'up' the eth1 interface...

Message from syslogd@localhost at Thu Nov 23 22:34:50 2006 ...
localhost kernel: Disabling IRQ #18

I just reconfigured it to to the original state - so that I can access the net.

By the way, how can I <pre> the output text in the post?

When YOU swapped the Ethernet Cables, YOU also swapped the IP's...Eth0 was [192.168.1.5] changed to [192.168.0.50]. Then Eth1 was originally [192.168.0.50] and changed to [192.168.1.5]. That was supposed to happen. But the mystery was the missing Gateway in YOUR output. That is where the connection became correct. Good luck.