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Old 07-22-2008, 01:18 PM   #1
pcCodingNut
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2 identical machines/setup - one sees server, other doesn't?


I have two machines with the exact same hardware and RHEL 4 WS installations and I configured them both exactly the same way (except the IP addresses, as I am using static IPs) and only one can see the server. Neither of them can see each other either.
I know it isn't the NIC or my cables because I also put Win XP on both machines and XP can see both the server and the other machine when I use the same static IP.

I am very new to linux so I have tried to do my homework before posting here (I also looked through all of the threads here that looked like they might be similar). I found some tutorials on setting up a static LAN and worked my way through them (hence one working client), but I don't know nearly enough to figure this out.

In reading through other threads I noticed that it is helpful to post the output of ifconfig, route, etc. so I will put them here (for both machines if that will help).

good machine output of: /sbin/ifconfig eth0
eth0 Link encap:Ethernet HWaddr blah:blah:blah
inet addr:blah.blah.blah.249 Bcast: blah.blah.255.255 Mask:255.255.0.0
inet6 addr: blah::blah.blah.../64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes: 0 (0.0 b)
Interrupt:169

bad machine output of: /sbin/ifconfig eth0

eth0 Link encap:Ethernet HWaddr blah:blah:blah
inet addr:blah.blah.blah.249 Bcast: blah.blah.255.255 Mask:255.255.0.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes: 0 (0.0 b)
Interrupt:169

good machine output of: /sbin/route

Kernal IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
169.blah.0.0 * 255.255.0.0 U 0 0 0 eth0
172.blah.0.0 * 255.255.0.0 U 0 0 0 eth0

bad machine output of: /sbin/route is identical

The only difference I can see is that the working one has that inet6 line being reported (and that machine has ipv6 disabled).

Any suggestions? Do I need to post more info before anyone can help me?
 
Old 07-22-2008, 01:24 PM   #2
XavierP
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Looking at your outputs, 2 things spring to mind:
Firstly both your ifconfig outputs are the same, they also both appear to be picking up the same ip address.

Secondly, you appear not to be picking up an IP address in either, from your route table. 169.xxx.xxx.xxx would indicate that neither have an address.

Here's mine for comparison:
Code:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.0.0     *               255.255.255.0   U     0      0        0 wlan0
link-local      *               255.255.0.0     U     0      0        0 eth0
default         192.168.0.1     0.0.0.0         UG    0      0        0 wlan0
default         *               0.0.0.0         U     1000   0        0 eth0
 
Old 07-22-2008, 01:36 PM   #3
PTrenholme
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Also, the Inet address reported - x.x.x.249 - is the same for both machines. Do you have them both turned on at the same time? If so, try changing the static IP address of one of them to a different value.
 
Old 07-22-2008, 03:03 PM   #4
pcCodingNut
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Oh, sorry for the confusion, I must have copied/pasted the same thing twice; the IPs are actually different (x.x.x.249 and x.x.x.250).

Let's try that again:

good machine output of: /sbin/ifconfig eth0

eth0 Link encap:Ethernet HWaddr blah:blah:blah
inet addr:blah.blah.blah.249 Bcast: blah.blah.255.255 Mask:255.255.0.0
inet6 addr: blah::blah.blah.../64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:777 errors:0 dropped:0 overruns:0 frame:0
TX packets:141 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:70482 (68.8 KiB) TX bytes: 16116 (15.7 KiB)
Interrupt:177

bad machine output of: /sbin/ifconfig eth0

eth0 Link encap:Ethernet HWaddr blah:blah:blah
inet addr:blah.blah.blah.250 Bcast: blah.blah.255.255 Mask:255.255.0.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes: 0 (0.0 b)
Interrupt:169

The output of /sbin/route on both machines is actually identical:

Kernal IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
169.blah.0.0 * 255.255.0.0 U 0 0 0 eth0
172.blah.0.0 * 255.255.0.0 U 0 0 0 eth0


...but how can that be if one works and the other doesn't?
 
Old 07-22-2008, 03:14 PM   #5
tredegar
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You'd make life easier for those of us with small brains if you just went ahead and posted the LAN IPs with out the "blah" bits. As this is your LAN, there's no security risk.
Thanks.
 
Old 07-22-2008, 03:27 PM   #6
pcCodingNut
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With the actual IPs:



good machine output of: /sbin/ifconfig eth0

eth0 Link encap:Ethernet HWaddr 00:1F:29:4E:8C:34
inet addr:172.21.50.249 Bcast: 172.21.255.255 Mask:255.255.0.0
inet6 addr: fe80::21c:23ff:fe42:97eb/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:777 errors:0 dropped:0 overruns:0 frame:0
TX packets:141 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:70482 (68.8 KiB) TX bytes: 16116 (15.7 KiB)
Interrupt:177

bad machine output of: /sbin/ifconfig eth0

eth0 Link encap:Ethernet HWaddr 00:1F:29:4E:8B:F2
inet addr:172.21.50.250 Bcast: 172.21.255.255 Mask:255.255.0.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes: 0 (0.0 b)
Interrupt:169

identical output of /sbin/route:

Kernal IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
172.21.0.0 * 255.255.0.0 U 0 0 0 eth0
 
Old 07-22-2008, 03:35 PM   #7
ynilesh
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If you just trying to set LOCAL LAN network between these 2 hosts. Its safe to put your ip addresss here.
OR

1. edit ifcfg-eth0 and set your ip address to 192.168.1.2 - first box. Restart network service and check "ifconfig".
2. edit ifcfg-eth0 and set your ip address to 192.168.1.2 - second box. Restart network service and check "ifconfig".
3. Get serial cable and connect them with each other.

Note : To restart network service use command "
Code:
service network restart
".

This should work.

- nilesh

Last edited by ynilesh; 07-22-2008 at 03:37 PM.
 
Old 07-22-2008, 04:06 PM   #8
pcCodingNut
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Just so everyone can have a good laugh, let me tell you how stupid I am. Because Windows automatically configures your network for you I didn't even think to check this but...I had the Ethernet cable plugged into eth1 instead of eth0 the whole time.

Well, I hope I made somebody's day. I'm actually laughing at myself so...
Thanks everyone who replied to my post.
 
Old 07-22-2008, 04:19 PM   #9
tredegar
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We are not laughing at you: We have all been there: USB speakers not working? But the modules are all loaded, and everything is configured perfectly, I just checked it again.

Compose Q for LQ. Some smart bas***d will ask "Are they turned on?". Check. Ooops! It's working now. Delete draft to LQ.

Pleased it's working. Cheer up and enjoy.
 
Old 07-22-2008, 04:48 PM   #10
XavierP
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At least you admitted it. I suspect that a large number of people would have quietly walked away. I think that this is not as rare as you think - if you support desktops in a corporate environment this is a basic type of question (dear users: an economics or other degree does not make you qualified to disregard basic support questions!) but if you are not one of us or if you are a backend person, it's a thing you'd disregard.

I have done this myself on occasion "of course i plugged it in. Oh, whoops, sorry, never mind"
 
Old 07-22-2008, 04:57 PM   #11
trickykid
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This is a reason I'll use the HWADDR= in each ifcfg-ethX file so the OS won't change them around even upon boot, which I've had happen before. I've had eth0 end up being eth1 upon a reboot once, caused havoc since it was a production machine. After a drive to colo and found issue, I made a personal goal to always set the HWADDR within each ifcfg file.

You are not alone my friend, you are not alone..
 
  


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