Unknown computer shown on my network

It may be a network-enabled device in your home, such as a television, Blu-ray player, game console, printers, etc that has joined your HomeGroup.  You just need to find it.  When you recycle power on your router, the devices just reestablish the connection.  The HomeGroup protocol will discover resources on your local subnet so they can communicate with each other.

What's connected to your router?  The HP at the end of IVANNANICOLE-HP may indicate a Hewlett-Packard device.  Who is Ivanna Nicole?

I believe when computers make things easier, such as HomeGroup, security will suffer.  I would limit network security to just your router.  To improve your network security, rename your wireless network…aka Service Set Identification (SSID)…change your router username and password, change your encryption key and enable MAC Address Filtering, which allows or denies clients to join your network by their MAC addresses.

Do you need HomeGroup?  If not, disable it.  If you need HomeGroup, secure it.  Search the Internet for articles on How to Disable HomeGroup or How to Secure HomeGroup.

Thanks for your prompt and detailed response, Bruce. I left HomeGroup and marked the IVANNANICOLE-HP as an Intruder on my Network and Sharing Center. The only thing I use besides my laptop is my Canon printer, which is usually off until I use it. It communicates through the USB port on my laptop only. My phone line is plugged into Cox's Motorola modem as I have basic phone and basic tv with Cox. I don't know any Ivanna Nicole, that's what's so scary. My router was originally set up on my previous laptop, which I no longer have but it was wiped clean professionally. This computer was connected to the internet through that computer, (an IT friend helped set it up) and I never installed the disk for the router in this computer because it was connecting fine and the wireless was working, so I didn't want to mess anything up. So for the past 3 years I've not been able to access the router as I used to on my previous computer, but since it was connecting, I didn't want to touch anything. I had noticed on the Connect to a Wireless Network listing that my network name was secure, there were a few other wireless networks in the area (very weak signals), and my Linksys generic network was unsecure. Then one stormy night...really...the wireless signal stopped working, but I could still connect to the router with the ethernet cable. So I'm thinking as long as I stay on my named network, my computer should be secure, but perhaps someone else is getting on the unsecured generic Linksys network. How far does a Linksys WRT-54G send it's SSID? I would think the only person who could possibly access it would be in the upstairs apt. or right outside the apt. building in the alley, which is unlikely.

So, would you recommend putting the Linksys disk in my computer and setting up a new network connection? I thought that maybe the COX Motorola modem wouldn't recognize a new network and I wouldn't be able to connect and therefore not be able to find any instructions and just be stuck. Do you sense some paranoia here?

Anyway, this morning I see that my computer is the only one listed under Network. So far. But I will try to change the things you recommend if I can access the router, otherwise try to set up a new network from the disk, which for some reason is extremely scary for me unless someone tells me it's easy and nothing will go wrong....anyone?

I think you're correct...it might be a neighbor on your network.  Your router will broadcast its SSID approximately 75 feet...depending on number and thickness of walls and any interference.  But if she's using her name (Ivanna Nicole) for her computer name, she may not be much of a threat.  However, you should secure your router.  This first step is to enable MAC Address Filtering.

You do not need the Linksys disk to administer your router.  The Linksys disc will load monitoring software for your router which, in my opinion, is sluggish and resource intensive.  If you know the username and password for your router, you can connect to it on this computer.

- Open your browser
- Type the following into the address bar:  192.168.1.1
- Enter your username and password

Let's start there.  Oh, your modem only needs the MAC address of your router maintain the network connection.

My username and/or password isn't being accepted. I wrote them down, and in 2008 I noted that they were the same. Can anything be done if one doesn't remember their username or password?

I did go into Advanced Network Sharing and made my home network category as "Public" as it said that was safest if I didn't need to share with other computers, and took off sharing anything, even the public folder and media streaming as far as possible, turned off Network Discovery and File Sharing, turned on password protected sharing, and still have 128 bit encryption on. So even though I can't access my router, I feel my personal computer and files are safe from sharing now.

It's good to know that the modem only needs the MAC address to have the network connection.

Thanks again for your suggestions and help.

That's great you're now protecting your files.  If you can't remember the username and password, you can reset your router to the factory default settings.  After you reset it, you can then build your network from scratch, which is easier than troubleshooting an unsecured network.  Let me know if you want that and I can send you some directions.  Yes, it's easy.

The router link may be secured (HTTPS)...so try https://192.168.1.1

It sounds like you're router may have been factory reset at some point.  Here's a link to the instructions for a WRT54G to resecure access.  You may also want to change the SSID to something unique that you'll recognize:

http://homekb.cisco.com/Cisco2/ukp.aspx?pid=80&app=vw&vw=1&login=1&json=1&docid=cfb50c0dc992443ab2405a782cca60f7_19073.xml

If your friend changed the default IP address of your router, you can research the address as follows:
1.  Click Start
2.  Select Run
3.  Enter:  cmd
4.  Click OK
5.  Enter:  ipconfig /all
6.  Document the following:
    - Physical Address, which is your MAC Address
    - Default Gateway, which is your router
7.  Enter:  exit
8.  Enter the IP address of the Default Gateway in your browser
    - Enter as http://###.###.###.###
    - Enter as https://###.###.###.###

If your username and password don't work, reset your router.  Before resetting your router, print the Cisco article from ChrisL to reconfigure it while you're without Internet access.

1.  How to reset your router:  http://homekb.cisco.com/Cisco2/ukp.aspx?pid=80&vw=1&articleid=4008
2.  After resetting your router, secure it:  http://homekb.cisco.com/Cisco2/ukp.aspx?pid=80&vw=1&articleid=24103
3.  Tips to create strong passwords and passphrases:  http://windows.microsoft.com/en-US/windows7/Tips-for-creating-strong-passwords-and-passphrases

Thank you, Chris and Bruce. You were correct that my router must have been reset at some point because I was able to get on it using admin as the password, not as the user name. I changed the password, changed the admin password, and used the MAC Filter to block the MAC address of the intruder. I changed the Key, the security to WPA2, and have the router so secure now that not even I can access it to change it any more. I still connect by ethernet, as I get the message that the password doesn't match when I try to connect wirelessly. Have to figure out which password to use--I thought it was the Key I set up. Oh well, as long as I can get on somehow it's okay. If I have any more problems, then I'll reset it to factory default, but since I was able to access it and make the changes, I think I'll see how it does for now. Thank you both again for your help.

From your laptop, you can't connect to the Internet wirelessly…or you can't connect to the router administration-page wirelessly?

Can't Wirelessly Connect to the Internet.
- Did you enter the new wireless network settings on your laptop?  You must enter the new encryption key, security mode (WPA2) and other changes on your laptop to match your router.

- Which Wireless MAC Filter option did you select:  Prevent PCs Listed from Accessing the Wireless Network…or…Permit Only PCs Listed to Access the Wireless Network?  Instead of blocking all wireless clients in your building, select Permit to allow ONLY your laptop to access the router.  After you select Permit, enter the MAC address of your laptop into the MAC Filter List.  Whichever MAC Filter option you select, the router needs MAC addresses to filter and thus either allow or deny access.  Follow the ipconfig /all procedures above to get your address.

Can't Wirelessly Connect to the Router Administration-Page.
- By default, Cisco disables Remote Management in its factory setting.  Meaning you can only access the administration utility via a wired connection.  As an added layer of protection, disabling Remote Management will prevent any wireless client from taking control of your router, locking you out and making changes that will leave your network vulnerable.  To enable wireless Remote Management, select Enable on the System page.  I recommend leaving it disabled.

- If you enable wireless Remote Management, enter your new username and password for the administrator…not the encryption key.

While you're administering your router, you should ensure its firmware is current.
- Go to http://homesupport.cisco.com/en-us/support/routers/WRT54G
- Select the Downloads tab
- Enter your Hardware Version
- Verify if this version matches the version on the System page of your router.

I can't wirelessly connect to the internet. I was able to change the MAC Filter option to only allow the addresses for my ethernet adapter and wireless adapter addresses. (I wanted to be careful, so I put them both.)  I did find the addresses using the ipconfig/all procedure. I went on the Network and Sharing Center on Windows and added the new wireless connection. I checked the Adapter properties and everything seems listed just as the other wireless networks. It's listed to connect automatically. It has the WPA2 and the encryption key listed. The only thing is when I unplug my ethernet cable from my laptop and try to click on the wireless symbol and select the new wireless network listed, it says it cannot connect and then brings up the troubleshooting popup. When I click to troubleshoot, it says it can't solve the problem.

As for the Router Administration Page, I kept the Remote Management disabled. I only get on it via ethernet cable.

The only thing I can think of is: to access the router, I have it on https 192.168.1.1, since you mentioned that it would be more secure. Maybe this is preventing the laptop from connecting as it is trying to go to http.192.168,1,1? (I left off the :// so it wouldn't link)

My next project will be to download a current firmware, as my version is from 2006. Thanks again for all your helpful links and suggestions.

Does the router assign an IP address to your wireless adapter?  You can run the ipconfig /all procures to verify.

If your wireless adapter doesn't have an IP address, check the following on your router:

- If you have DHCP enabled, how many IP addresses is your router assigning to clients?  If you set it to one for added security, your LAN card is using the only available IP address.

You would think unplugging the Ethernet cable would release the IP address.  No.  Disabling a card or unplugging a connection on your laptop will not release the IP address in your router.  DHCP on your router leases an IP address for a specific period of time...usually 24 hours...so it will still be assigned to your LAN card unless you force your router to release it.

What is DHCP?  Dynamic Host Configuration Protocol automatically assigns temporary IP addresses to clients logging into an IP network.  DHCP resides in your router to eliminate having to manually assign permanent "static" IP addresses to devices.

- Set the number of clients in your router to two...or whatever number of network cards would connect to your router, such as a television, Blu-ray player, game console, media player, etc.

- Ensure you entered the correct wireless MAC address in your router.

If these aren't the culprit, we can check the LAN/WAN Switching in your BIOS.  This could be the case after upgrading Windows XP to Windows 7.  What type of laptop do you have?