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Something wrong with my network (hosts unreachable)

Posted on 2003-10-25
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Last Modified: 2010-04-11
I have a network that consists of

4 divices. A Microsoft Broadband router (its a wirles and wired hub, I dont need its routing features its in hub mode, I bought it because it was inexpensive), a Windows 2000 Server system (this is the router, its connected via Ethernet to the hub, a Windows 2000 Pro System, its connected via Ethernet to the hub and a Sharp Zaurus SL-C760 PDA, which connects wirelessly.

My problem is this.
The Zaurus and Pro system can connect to systems outside the LAN and to the Windows 2000 Server but not to each other. Why is this?

Thank you for your time,
Arrummzen
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Question by:Arrummzen
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by:CycLonE
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Arrummzen, you didn't define your problem properly.

Since (hosts unreachable) => no network connectivity => it's not related to users/groups/permissions

1- Check your network connectivity wether hub/cables...
2- Check your TCP/IP config (also you didn't specify your network protocol)
   - if you have TCP/IP: try to ping 127.0.0.1 on all devices (to check if TCP/IP is configured correctly)
   - try to ping all devices from the other two.

usually the problem you indicated is network connectivity problem or networking protocol misconfiguration.

Good luck ;-)
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by:Arrummzen
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>> 1- Check your network connectivity wether hub/cables...

All are connected

>> 2- Check your TCP/IP config (also you didn't specify your network protocol)
I am using TCP/IP, the systems are configured from my DHCP server which is on the Windows 2000 Server. What information do you want exactly, as far as I can tell the configuration is correct (but if it is then it would work rite?).

>>- if you have TCP/IP: try to ping 127.0.0.1 on all devices (to check if TCP/IP is configured correctly)
It works. ping -c 4 192.168.4.13 works on all divices as well, however the Win2kPro Systme and the Zaurus can ping only the Windows2kServer not each other. 192.168.4.13 is the server.

>>- try to ping all devices from the other two.
They cant ping each other, but they can ping the server (they cant ping the MS hub, although the server can ping it, I dont know how to ping from the hub.

>>usually the problem you indicated is network connectivity problem or networking protocol misconfiguration.
It might have something to do with the way the gateways are set up or routing, but I have no idea.

Thank you for your time,
Arrummzen
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by:ShineOn
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It sounds like a routing issue to me.  Are you sure the broadband router device is not doing any routing, DHCP, DNS, NAT?  Does the server have 2 nics - one for public, one for private, and the private side is on the same IP subnet as the other 2?
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by:Arrummzen
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Im not using NAT so thee shouldnt be any private or public networks. There is
Server NIC 1 : 192.168.1.13
Server NIC 2 : 192.168.4.13

Does it matter if the hub is in routing mode or briding mode?

>> Are you sure the broadband router device is not doing any routing, DHCP, DNS, NAT?
I hve all that stuff is disabled, It doesnt have DNS support, DHCP is disabled, I dont see how it could use NAT. But if it is trying to it might be a problem, how do I check?

Could it be a problem with my gateway settings?

Thank you for your time,
Arrummzen
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by:snerkel
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Afraid your description of your network is confusing, so to basics

Assuming your server NIC 192.168.4.13 is connected to the Broadband router.

1. Nothing should be connected to the WAN port on the router
2. Subnet mask for all devices need to be 255.255.255.0
3. All IP addresses of Wireless device, router, and XP PC should start 192.168.4.
4 Only setting required in router is to disable DHCP and to set its LAN IP so that it starts 192.168.4. with a subnet 255.255.255.0
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by:Arrummzen
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>>1. Nothing should be connected to the WAN port on the router
True
>> 2. Subnet mask for all devices need to be 255.255.255.0
True
>> 3. All IP addresses of Wireless device, router, and XP PC should start 192.168.4.
true, save its 2000 pro system, (there is actualy a few other Systems, a BSD box, and two Linux Systems, but they dont rely have any effect on the problem and only make things more complicated).
>> 4 Only setting required in router is to disable DHCP and to set its LAN IP so that it starts 192.168.4. with a subnet 255.255.255.0
Thats all set correct

Any more questions?
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by:ShineOn
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Tell me if I understand or not.  

1)  You have a LAN based on the use of a broadband router's switched ports as at least part of the infrastructure.

2)  You use a Windows server to connect to the internet, probably using internet connection sharing (ICS)

3)  Your Windows server has 2 NICs, both with private IP, 192.168.1 plugs into your DSL or cable modem.  192.168.4 is the network you use for all the rest.

4)  The server and these two devices, the PDA and a Win2K Pro PC, all connect to the router, whether direct or wireless.  They both can see the server, and they both can access the Internet, but niether can see each other. You tried a ping of one device to the other (PC to Zaurus, or vice-versa) and get a "host unreachable" response.

5)  You have other devices in your network but don't want to say if they have any similar problems or even whether they are all on the same IP network.

Assuming I have it right this time, these are my questions and comments:

1)  If all of the devices are on the same network, 192.168.4, then unless for some reason ICMP is being blocked somewhere, a PING should give a response from any device.  Server to pda, pda to server, server to pc, pc to server, server to BSD, BSD to pda, pda to Linux #1, Linux#1 to PC, etc.  Are you able to get a PING response from all devices to all devices except between the Win2K PC and the PDA?

2)  Regarding the gateway settings:  if your gateway settings were incorrect, you shouldn't be able to get to the internet from anything but the server.  If they are all on the same IP network, 192.168.4, and they are connecting through a hub or switch, and you are not doing subnetting, then they shouldn't need to use the default gateway to see each other, just to see anything outside the 192.168.4 network.

3)  Does it matter if hub is in routing or bridging mode?  It might.  What does the documentation say about this?  Could it be trying to route between the wireless and the wired for some reason?  That could be why you get a ping response from the router when pinging from the server, but not from the other devices plugged into the router.  A bridge connects multiple segments of the same network together, while a router is used for connecting separate networks together.  Is it in router mode right now?  Have you tried bridging mode?

4)  Just to give you some information - assuming you don't know this yet based on your comments  - when you are using a server with two NICs on two networks as a router, with one of the networks connecting to the internet and the other network connecting to your private LAN, then you still have a "public" and "private" side, even though you are using private-range IP addresses on both NICs.  The "public" side of your server is the one that hooks up to the internet device, and since it is a private IP address, your ISP is doing some sort of NAT, whether at their location or at the DSL/Cable modem.  Since connecting to  and accessing the Internet isn't a problem for you, we should ignore that part of the picture and concentrate on what's happening with your 192.168.4 network only.

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by:Arrummzen
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>> 1)  You have a LAN based on the use of a broadband router's switched ports as at least part of the infrastructure.

Yes

>> 2)  You use a Windows server to connect to the internet, probably using internet connection sharing (ICS)

Not correct, its a Windows 2000 Server System with two NICs one attached to the broad band router, and the other connected to another network which is 192.168.1.x (the one with the problems is 192.168.4.x) this network connects to the Internet. The Windows 2000 System is useing normal internetwork routing not ICS. The routing table is hand writen (all static routes).

>> 3)  Your Windows server has 2 NICs, both with private IP, 192.168.1 plugs into your DSL or cable modem.  192.168.4 is the network you use for all the rest.

No, the Internet is reached via another Network, the Windows 2000 Server system connects to another broad band router, which IS pluged into a cable modem, and that is in routeing mode.

>> 4)  The server and these two devices, the PDA and a Win2K Pro PC, all connect to the router, whether direct or wireless.  They both can see the server, and they both can access the Internet, but niether can see each other. You tried a ping of one device to the other (PC to Zaurus, or vice-versa) and get a "host unreachable" response.

Correct

>> 5)  You have other devices in your network but don't want to say if they have any similar problems or even whether they are all on the same IP network.

They are on the same network and have the same problems, but they dont realy matter, whats the differnce, bettween 1 computer and 10 computers with the same problem (once you solve it for one, you can solve it for all). Just so you know, one is a freeBSD System and the other two are RedHat Linux Systems.

>> 1)  If all of the devices are on the same network, 192.168.4, then unless for some reason ICMP is being blocked somewhere, a PING should give a response from any device.  Server to pda, pda to server, server to pc, pc to server, server to BSD, BSD to pda, pda to Linux #1, Linux#1 to PC, etc.  Are you able to get a PING response from all devices to all devices except between the Win2K PC and the PDA?

No, Systems on the Network can only ping or connect to the Windows 2000 Server (telnet, ftp and ssh wont work bettween the systems ether).

>> 2)  Regarding the gateway settings:  if your gateway settings were incorrect, you shouldn't be able to get to the internet from anything but the server.  If they are all on the same IP network, 192.168.4, and they are connecting through a hub or switch, and you are not doing subnetting, then they shouldn't need to use the default gateway to see each other, just to see anything outside the 192.168.4 network.

Ok, thats what I thought, but I wasnt sure. They are all configured by the Windows 2000 Sever via DHCP.

>> 3)  Does it matter if hub is in routing or bridging mode?  It might.  What does the documentation say about this?  Could it be trying to route between the wireless and the wired for some reason?  That could be why you get a ping response from the router when pinging from the server, but not from the other devices plugged into the router.  A bridge connects multiple segments of the same network together, while a router is used for connecting separate networks together.  Is it in router mode right now?  Have you tried bridging mode?

I dont want to put it into briding mode because if I do I will no longer be able to change settings on it (rite now I can connect to it via HTTP at the address 192.168.4.1, but if I put it in bridging mode I wont be able to access it without reseting it to deffault settings). This is bad because if I do I wont be able to add other divices to the WMAC filtering or change the WEP key. Ill read threw the documentation soon.

>> 4)  Just to give you some information - assuming you don't know this yet based on your comments  - when you are using a server with two NICs on two networks as a router, with one of the networks connecting to the internet and the other network connecting to your private LAN, then you still have a "public" and "private" side, even though you are using private-range IP addresses on both NICs.  The "public" side of your server is the one that hooks up to the internet device, and since it is a private IP address, your ISP is doing some sort of NAT, whether at their location or at the DSL/Cable modem.  Since connecting to  and accessing the Internet isn't a problem for you, we should ignore that part of the picture and concentrate on what's happening with your 192.168.4 network only.

Ok, all the Networks are private from the Internet, but 192.168.4.x is not private from 192.168.1.x,
NOTE: I can ping Systems on 192.168.1.x, 192.168.2.x and 192.168.3.x from divices on 192.168.4.x however I cant ping hosts on 192.168.4.x from 192.168.1.x, 192.168.2.x or 192.168.3.x.

Thank you for your time,
Arrummzen
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ShineOn earned 250 total points
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It sounds like you are using the packet filtering features of the Win2K Serve, or something along the line is blocking certain packet types/ports.
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by:Arrummzen
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Sorry for taking so long to close this question, I fixed the problem a few weeks ago. It turns out that the problem was that MAC filtering being done by the Microsoft hub/bridge. I thought that MAC filltering applyed only to systems that connected via WLAN. But apparently it applys to ground systesm as well.

Thank you for your time,
Arrummzen
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