Network Problems.

Sully

Hey,

I was recently called to a house to fix a problem on their network, and im stumpped on how to fix it. Iv a wireless network set up here at home and it was a pain to set up originaly, so im not to fond of networks at the moment :P

The network consists of two PCs wired via an ethernet cable to one of those Netopia(?) Eircom routers that is supplied with the broadband. They are on the same workgroup and IP seems to be assigned by the DHCP.

Only one PC (the one beside the router) is connected sucesfully and is able to use the web. The other has "Limited or no connectivity" and "Repairing" doesnt work as it cant renew the IP address. I can get it on the network if I assign it an IP by TCP/IP Settings of the network connection but then the internet doesnt work as its unable to resolve the server (DNS info not supplied when setting TCP/IP settings).

I tried running in MSDOS;
ipconfig /flushdns - command worked OK.
ipconfig /renew - failed. Something about cant preform this operation on a socket (not 100% sure of the wording).

This always did work, but there PC was riddled with viruses and spyware and I was given the job of cleaning it up (They had AVG on it, but it wasnt detecting ANY viruses. It was up-to-date also. Installed NOD32 and it fixed the problem. Used Ad-Aware scanner to remove all spyware. The OS is pirated - the last person to repair the PC put on XP Pro with an invalid key - but MS detected it now) and when I brought it back it never worked - which is odd as I only used wireless internet here once and removed ALL settings and additional software when I was finished (I could only get the net to work wireless once, after a re-boot it was "Limited or no connectivity" so I just removed it and carried on with my work).

Not to sure what the problem is, seems a bit odd but is probably simple to fix. Any ideas?

Thanks in advance.

gouche

Hey,
How is the network set up? Am I right in thinking one computer is connected to the router and teh other is connected to that comp? If so, are you sure you have the right cable? The one you need is a CAT5 crossover.
If you do, it shouldn't be much harder than running Internet Connection Sharing on the comp connected to the router. Assumming your running Windows on both comps.

liamo

"Limited or no connectivity" is the message you get when the PC is unable to get a DCHP supplied IP Address.

If you have connectivity when you set the IP Address manually then I expect that the DHCP server isn't working.

You can set the DNS and gateway IP Addresses manually. To find out what they are, go to the other PC and, at a command prompt, type ipconfig /ALL. This will tell you the Default Gateway and DNS Server addresses. It will also tell you if DHCP is enabled on this PC - because you don't appear to be sure.

If it was me, I'd fix the DHCP problem but as this is a small home network, simply setting the IP Addresses manually will be ok.

One thing that has saved me loads of time on a number of occasions is to write down the settings on a piece of paper and selotape it to the PCs. In a home environment where people don't really know what they're doing you're going to be setting these addresses again.

Regards,

Liam

Sully

gouche wrote:

Hey,
How is the network set up? Am I right in thinking one computer is connected to the router and teh other is connected to that comp? If so, are you sure you have the right cable? The one you need is a CAT5 crossover.
If you do, it shouldn't be much harder than running Internet Connection Sharing on the comp connected to the router. Assumming your running Windows on both comps.

From what I can gather (the room is a mess and the cables are hidden along the walls and ceelings etc) PC1 has a cable going from it to the router. Then PC2 has a cable going from it to the router aswel. So the two PCs are directly connected via the correct cable (I would presume, as they had someone who was experienced with setting up networks put it in place).

Im nearly possitive its not a cable/driver/card error as its not like it cant connect at all, it just cant get an IP and work away.

liamo wrote:

"Limited or no connectivity" is the message you get when the PC is unable to get a DCHP supplied IP Address.

If you have connectivity when you set the IP Address manually then I expect that the DHCP server isn't working.

You can set the DNS and gateway IP Addresses manually. To find out what they are, go to the other PC and, at a command prompt, type ipconfig /ALL. This will tell you the Default Gateway and DNS Server addresses. It will also tell you if DHCP is enabled on this PC - because you don't appear to be sure.

If it was me, I'd fix the DHCP problem but as this is a small home network, simply setting the IP Addresses manually will be ok.

One thing that has saved me loads of time on a number of occasions is to write down the settings on a piece of paper and selotape it to the PCs. In a home environment where people don't really know what they're doing you're going to be setting these addresses again.

Regards,

Liam

Id rather fix the DHCP server - can you give some insturctions on how to make sure its all set up and running OK? Its been a long time since I started working with networks, and iv only ever done two in the past.

Good idea about taking notes of IPs etc, I will do that. And cheers for the heads of on ipconfig /all - I forgot about that one.

irlrobins

Sully04 wrote:

Im nearly possitive its not a cable/driver/card error as its not like it cant connect at all, it just cant get an IP and work away.

Assumption is the mother of all fuckups. Since both PC's are connected to the same router and one is getting an ip assigned by dhcp and the other is not, then a faulty cable or card could be a possibility. Try a new cable, or connect PC1 to the cable PC2 is currently using and see if it works.

If you're setting up the ip address of PC2 manually, then the gateway and primary dns is usually the ip address of the router.

Sully

Well I dont have any spare cables to use and the ones they have are wired into the house so thats kinda hard to start ripping em out!

Isnt it possible that the DHCP server isnt working on the PC causing the trouble?

irlrobins

Sully04 wrote:

Well I dont have any spare cables to use and the ones they have are wired into the house so thats kinda hard to start ripping em out!

So move PC1 to PC2's location and plug it in there and see if it works. all you need to move is the case.

Sully04 wrote:

Isnt it possible that the DHCP server isnt working on the PC causing the trouble?

DHCP server presumably is on the router, not on either of the PCs. You could see if DHCP client service is running ok on PC2. Control Panel->Administrative Tools->Services. See if DHCP client is started. (Should be set to Automatic).

liamo

Id rather fix the DHCP server - can you give some insturctions on how to make sure its all set up and running OK? Its been a long time since I started working with networks, and iv only ever done two in the past.

Is the working PC receiving a DCHP supplied address? This is the reason I specifically mentioned the DHCP Enabled setting in the output from ipconfig /all. If the working PC is receiving a DHCP response then the DHCP server is working and you can start looking elsewhere for your problem.

As irlrobins pointed out, the DHCP server is presumably on the router. You should be able to log in to it with a browser and check the status of the DHCP server.

If the DHCP server is working and the PC is still not receiving an IP Address, you could try swapping the two PCs. If, after the swap, the original PC is still not receiving an IP address then it's likely to be a dodgy network card on the PC.

Regards,

Liam

Sully

The working PC is able to be assigned an IP address.

I will try the swap, im going over in a few hours

Stacksey

whats the problem here, it sounds like you have a 4 port netopia router and all you require is internet access for both machines. if both machines are set for DHCP there should be no problems, NAT will provide internet sharing here

Conar

Hey guys!

If the DHCP server is working as you say it is and the PC & NIC are working which the static IP test proves then I would imagine that for some reason they have limitted the DHCP scope to one address.

Log on to the router, enter the DHCP section and see if its either limited to one connection or if the address range only contains 1 IP.

Sully

Just back from taking a closer look at the two PCs. I got the Gateway/DNS from the working PC and set it on the one that doesnt work - and while its connecting to the internet, they still cant browse the internet.

I swapped PCs about, and it made no difference. So that rules out the cable being at fault - both cables work fine, its just the one PC which isnt able to automaticaly get an IP assigned and when set manualy its not able to browse the web.

The netopia router has a blue and yellow cable going from it connecting to the two PCs - the yellow one connects to the working PC (PC1) and the blue one connects to the unworking PC (PC2). If I swap PC1 to the area where PC2 is and connect it using the blue cable - its working perfect. When I bring PC1 (the one with the problem) to the new location and connect it to the yellow cable - same issues arise.

So it seems that there is some hardware/software problem on PC2 causing it unable to connect to the network fully and get an IP address, and work with the web. All I did when I was given the PC was clean it using Adaware and NOD32 - cleared a lot of ****e from the PC. I was able to get a connection via my wireless network here at home (wireless USB stick) but it didnt last very long. After booting into Safe Mode and running the scans and going back to normal mode - I couldnt get the wireless network connection to work. Not sure if thats related. I removed all trace of my wireless software and settings from the PC.

All I know is when the PC was brought back it was unable to connect to the internet. They installed the Eircom Broadband software (using the disc I believe) to see if it would get it to work but it didnt. Same "Limited connectivty" error.

So now im still stuck. Any ideas?

irlrobins

Well considering there was a lot of ****e on it maybe the whole system is fecked. Assuming some of the ****e was viruses. Might be quicker in the long run to backup, wipe and reinstall.

In the mean time try resetting TCP/IP. At cmd prompt enter "netsh int ip reset c:\resetlog.txt".

Then set PC to get IP via DHCP. See how that goes.

Sully

There was about 10 viruses and over 500+ spyware. Its likely it fecked it up, as it was when the PC was cleaned it stopped working.

What affect does resetting TCP/IP do? (Interested to know, never done it before!).

Also, I presumed if I just configured the network settings it recongises that an IP is assigned auto via a DHCP Server, do I have to set something on the PC?

irlrobins

Sully04 wrote:

What affect does resetting TCP/IP do? (Interested to know, never done it before!).

http://support.microsoft.com/default.aspx?scid=kb;en-us;299357

Sully04 wrote:

Also, I presumed if I just configured the network settings it recongises that an IP is assigned auto via a DHCP Server, do I have to set something on the PC?

In the properties of the network card, Select Internet Protocol (TCP/IP) and click on properties. Select Obtain Ip Address Automatically and Obtain DNS Server Automatically. That is all.

axer

It is possible that websense (spyware) was installed because when this is removed by spyware removers it can stop you surfing the net on the infected computer. You need to get a fix for it here:
http://www.cexx.org/lspfix.htm
You can run Hijack this and see if it tells you about an LSP problem.

Sully

Cheers lads, ill keep you updated!