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PC cannot be seen on network

Posted on 2002-06-06
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I have a network problem. There are 4 PCs running Win 2000 on a peer to peer network, originally an old 'thinnet' coax cable, but the system has all been updated to Cat5 with a hub and a Netpilot providing email and internet access across the network.  Since the upgrade, everything is now working ok except network access over the LAN to PC3 from other PCs.   PC3 has email and internet access, and can ping all other PCs, but cannot see them.  No other PC can ping PC3.  As PC3 has email and internet services, the network must be working, but I have run out of ideas to locate the problem.  Please can anyone help?

 John
 
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Question by:jcolles
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by:cincin77
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Is there a firewall software installed on PC3?
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by:PeterMac
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Check Identification details on all PC's, make sure they are all in same work group. Also check IP addresses for all machines, does ping fail if you use IP address rather than name.

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by:jcolles
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There is no firewall on PC3, all pings were done using addresses.   The workgroup is the same on all PCs (infact it has not been changed since before the update)  I have also tried changing the ip address of PC3, but the results are always the same.
Regards John
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by:cincin77
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Lets go through the problem;
4 pcs
a hub
only pc3 has internet access (through???)
pc3 can ping everyone
noone can ping pc3
other pcs can ping themselves????
all machines have the same subnet mask????
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by:jcolles
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cincin77
That is correct except that all PCs have internet and email access through a device called a netpilot.  This was fitted by the telephone company and is presumably a router.  It includes a firewall and also some disk space, plus logging of comms statistics.
All PCs can ping themselves and also the netpilot, all PCs have the same subnet mask 255.255.255.0

Regards John
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by:rid
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Is there a way of viewing/adjusting the firewall properties? This sounds like a restriction in the firewall.

Regards
/RID
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by:t1n0m3n
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could it be a bad port on the hub?  switch ports with another pc and see if the problem stays or moves with the port.
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by:jcolles
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I have switched the PC onto a different hub port with no change, but as the email and internet works, it was a bit of a long shot.   I have not delved into the firewall settings, but again it should be the same for all PCs as nothing has been altered since it was installed.
Regards John
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by:jcolles
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I have removed and re-installed all netwworking protocols, clients and services, but the problem is still there.   Incidentally there is a hub serving the network and the router is behind the hub, so a router firewall cannot be the problem.  Has anyone any more ideas?
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by:rid
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See if I got this correct:
The 4 PC:s are on a hub, the hub connects to the router as well.

PC3 can use internet services and can ping other units.

Other units can use internet as well, but they cannot ping PC3.

Units except PC3 can see each other on the network.

If this is correct it is a strange situation. It seems like a firewall were active on PC3. You say there isn't; no chance of a user installing something and not telling you?

If you go through TCP/IP settings in detail for PC3 and another machine, do you see any differences at all?

Regards
/RID

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by:PeterMac
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Very strange situation, I suspect that you may have more than one problem causing this situation.

I can't see it being a routing problem as such, since other PC's need a valid route to reply to the "Ping".

Problem 1) Other PC's can't see PC3, PC3 can't see other PC's in network neighbourhood.

I have seen similar problems, usually associated with Domain SID's. A situation can occur where the same name can have a different SID value, effectively giving you two different Domains with the same name. Possibly this is what has occurred with your workgroup. If for example PC3 was added to the workgroup with no other PC's running. W2000 will not display PC's in network neighbourhood if they are not from same Domain or Workgroup, as default. If this is the problem you should still be able to add the missing PC's manually using network places. Alternatively try moving PC3 out of the workgroup, and then back in while other PC's are running.

Problem 2) Other PC's can't ping PC3. Only reasons I can think for this are:-
   1) PC3 has been set up with a restriction preventing response to Ping.
   2) Other PC's have a bad cached IP address for PC3, would only be relevant if Pinging by name, and IP address for PC3 has changed recently.

    Don't know 2000 well enough to suggest where to look for 1), you can use "nbtstat" command to check 2)
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by:jcolles
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I have noticed that there are a number of errors showing in the system logs, the following two may be a pointer?

IPNATHLP  Event ID 30013
The DHCP allocator has disabled itself onm IP address 10.0.0.3 sice the IP adress is outside the 192.168.0.0/255.255.255.0 scope from which addresses aer being allocated to the DHCP clients.   To enable the DHCP allocator on this IP address please change the scope to include the ip addresses, or change the IP address to fall within the scope.

Service Control manager  Event ID 7001
The DNS client service depends on the TCP/IP Protocol Driver Service which failed to start because of the following error:
The system cannot find the file specified.

I am not sure why DHCP is running on this client, could it be a hangover from an attempt some time ago to use internet sharing?

Could this have any relevance to the problem?   I have now disabled DHCP, but the problem remains.

Regards John
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by:PeterMac
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Don't think the DHCP service is likely to be cause of problem, since it wasn't really running anyway. Possibly problem may be due to a hangover from trying to use it though.

The second error is more telling, a lot more than just DNS depends on the TCP/IP protocol driver. I would reccomend removing and reinstalling TCP/IP protocol on this machine, especially if it is PC3.

Also check again IP addresses and masks on all PC's, and your netpilot, to make sure they are compatible.
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by:jcolles
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I have previously removed and re-installed TCP/IP and the other items in the network window, then set up again,  PC3 does work with the netpilot with email and internet, but cannot be seen with the other PCs.
Regards John.

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by:PeterMac
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John

      I'm not in the office for next couple of days, so if you don't here any further from me before Friday it is not because I have given up on you.

     There is obviously something strange going on with your IP addressing, try the following, and see if anything strange shows up.

       On each PC run command "nbtstat -c" from command prompt.
       On each PC run "Ping" from command prompt, using both local machine Name, and IP address.

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by:jcolles
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I had another look today at the error messages on PC3.  There are 3 which might be significant, especially the first one.
I tried nbtstat -R and I am now able to ping all PCs from PC3 using address or name, but if I use 'computers near me, it eventually times out saying 'WORKGROUP not accesible'.  I still cannot access PC3 from elswhere.
Note that the computer called 'Dell' is a laptop running win98, which I added to the network.
If I change the workgroup name on PC3 to something else, then I can see PC3 only using 'computers near me', but if I cnage it back to WORKGROUP then I get 'WORKGROUP not accesible' and cannot even see PC3.
The error messages results of nbtstat are listed below.
Regards John


Source: NetBT
EventID 4319   PC3
A duplicate name has been detected on the TCP network.  The IP address of the machine that sent the message is in the data.   Use nbtstat -n in a command window to see which name is in the conflict state.

                     --------------------

Source: MRxSmb
EventID: 8005  Computer PC3
The Browser has received a server announcement indicating that the computer PC3 is a master browser, but this computer is not a master browser

                     --------------------

Source Workstation
EventID 3113 Computer PC3
Initialisation failed because the requested service redirector could not be started

                     --------------------
nbtstat -n

node IP address [10.0.0.3] scope Id: []

            NetBIOS Local Name Table

Name                 Type            Status
-------------------------------------------------
PC3             <00> UNIQUE         Registered
PC3             <00> UNIQUE         Registered
WORKGROUP       <00> GROUP          Registered
WORKGROUP       <1E> GROUP          Registered
PC3             <03> UNIQUE         Registered
PC3             <6A> UNIQUE         Registered
PC3             <87> UNIQUE         Registered
ADMINISTRATOR   <03> UNIQUE         Registered

                     --------------------

nbtstat -n

node IP address [10.0.0.3] scope Id: []

            NetBIOS Local Name Table

Name               Type         Host Address   Life [sec]
-------------------------------------------------------------
PC1             <00> UNIQUE        10.0.0.1       217
PC2             <00> UNIQUE        10.0.0.2       192
DELL            <00> UNIQUE        10.0.0.10      152
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by:PeterMac
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John,

       Looks very much like you have 2 workgroups, both with the same name "WORKGROUP", but with different internal ID's. Problem is Windows tends to remember the name and original ID, probably somewhere in registry, and so even leaving and rejoining the workgroup may not solve the problem. Best advice I can give is to create a new workgroup, "MYPCS" or similar, and move all PC's into the new Workgroup. You should also run the "nbtstat -R" on all PC's, to make sure there are no bad names, or ID's in the cache. I am pretty sure this will cure your problems.

Trouble is some functions work only using the name, others use the SID for the workgroup, hence whenever PC3 tries to contact it's "WORKGROUP", it gets a not found response because it is using the wrong SID, same applies to the other PC's. The response you get when you move PC3 to a different workgroup is normal for WIN2000, WIN98 can't ever see a PC in a different workgroup. You should be able to ping by IP address though.
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by:jcolles
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PeterMac.
That sounded good so I have changed the workgroup name on all PCs.   Result -  all PCs communicate except PC3 which is still isolated!.

nbtstat -n gives:-

node IP address [10.0.0.3] scope Id: []

           NetBIOS Local Name Table

Name                 Type            Status
-------------------------------------------------
PC3             <00> UNIQUE         Registered
PC3             <20> UNIQUE         Registered
SECKFORD        <00> GROUP          Registered
SECKFORD        <1E> GROUP          Registered
PC3             <03> UNIQUE         Registered
PC3             <6A> UNIQUE         Registered
PC3             <87> UNIQUE         Registered

                    --------------------

Tough one?
Regards John
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PeterMac earned 200 total points
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Very tough,

Sorry not to have answered sooner, but had a major problem on a client system to deal with. Have been thinking about your problem though, something very weird is going on on that system. Error messages seem to suggest that you have two PC3's on your network ?, may be worth checking network settings again, about only thing I can think of that could be doing this is two network card definitions in the PC, did network card autodetect, or did you have to set it up manually ?, I have seen some similar effects on an NT machine that had Network card installed twice, two TCP/IP definitions effectively for the same card. In that case they were set up with different IP addresses, and effects were not quite what you are getting, but I suspect that if you have two definitions with same IP address that could cause most of problems you have.

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by:jcolles
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PeterMac.
Thanks very much for all your help.   Having changed the workgroup name on each PC then re-booted it, the problem still remained, however I went in this week, and miraculously PC3 had re-appeared on the network.  I can only imagine that when all PCs were turned off and then re-booted the next day, that things finally sorted themselves out.   Not a very satisfactory result so far as understanding the problem goes, but at least everything is now working again.
Thanks for your help, I was geting desperate!!
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by:PeterMac
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John,
         NO problem, thanks for the grade. Always worth running "nbtstat -R" after making changes like this, but need to run it on all machines on network, to make sure no old info still in caches.

                   
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