Seperate Modems?

lasor

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Hi All

Could anybody tell me if this is possible and can you forsee any problems or issues with it?

What I want to do is use my current sub modem to connect to one PC and use my hacked modem to connect to another PC.

Currently I am using my hacked modem on a wireless network but what I want to do is hardwire my sub modem into PC one while leaving my wirless network intact to use my laptop with hacked modem.

Here is how I intend to do it. Place splitter on coax cable and run too sub modem. connect cat cable from sub modem to PC one, using seperate nic. this should give me sub connection. I need to keep my wireless network intact as I use drive mapping and sharing of printers etc...and my hacked modem is on my wireless network.

Can anybody see any issues with this either with security or setup? If anybody can think of another way to do this then pl,ease let me know. The reason I want to do this is because my bloody kids keep nicking my bandwidth with there music and video downloads so I want to give them there own modem on PC one to free up my modem on the wireless network..

It would be great if I could somehow have both modems running on PC one and then beable to chose which user connects to which modem. For example when kids are on PC and logged in they automaticaly default to sub modem, when I am logged in I default to hacked modem..That would be good if it was workable??

Thanks in advance for any advice or help on this...
 
Hi mate,

Just be sure I am following you properly, could you look at the attached image (example.jpg).

From what you are saying, yes you could do what you want to do. You can use a splitter on the coax line to run to two modems providing the power level on your cable feed is sufficient; it usually is though. I can run about 2/3 modems and 4 STB's before power becomes an issue.

You can leave your wireless network intact for file/print sharing etc. Each PC can also have their own modem connected via a second NIC or USB (NIC is the better option).

From a security perspective there isnt much you need to take into account. Firewall your modem connection and leave your internal (the wireless connection) unprotected (I'll assume you have already sorted out your wireless security via WEP, WPA etc).

What you do need to do though for a little extra security (this is something alot of people miss and really shouldnt) is to remove the ability for the Microsofts file and printer sharing client to use the modem for connections. To do this you simply need to uncheck the correct boxes in the properties of the NIC connected to the modem. Only TCP/IP is required for your internet connection to fully function (you can keep QoS if you use services that use the 'quality of service' protocol, that is usually streaming audio/video etc), please see the attached image (bindings.jpg).

The following info is just hints/tips, please ignore it if you already know what I'm on about. :)

Now that you have both computers with their own internet connection, you need to make sure your internal network is going function flawlessly. As you probably know, you can use 'My Network Places' (Network Neighbourhood on older windows OS's) to browse to other computers on your network and you have probably noticed that the computers do not always appear even though they are switched on. As much as this can seem like a bit of a mystery there is a good reason for why this happens. When your computers are powered up, during the boot process there is an election held between all computers running certain microsoft network services (all microsoft OS's do this by default) to see which computer is going to take on the role of 'master browser'. This can be any active computer on your network, if only workstations are present a random number is seeded and its a game of chance to see whcih computer gets the job; if there is a server present, the server is automatically assigned the role, if there are two servers, the election is held between the servers; anyway, you get the point lol. Now the master browsers job is to keep a list of computer names and ip addresses. This list is created and amended when the master browser receives broadcasts over the network from other computers informing it of their presence on the network, telling it their name and new IP. Now if the master browser is not powered up when another computer boots up, the election is held and the only powered computer gets the job and thus a new (empty) browse list is created, then when you fire up the computer that used to be the master browser its list is cleared and the computers dont see each other in 'My Network Places' until the new master browser receives the broadcasts and updates its lists. ........ **** taking a breath ****

This can cause problems when trying to browse file and printer shares simply with the PC not always finding the others. There is a way around this though, you just need to keep track of your machines, which is simple enough providing you dont have a few hundred computers on your network. :) This is done by editing a few files on each workstation. The reason you edit these files is so your computer doesn't go asking the cable internet server where you PC2 is located (ofcourse the cable server wont know). This is called 'name resolution'; how your computer turns a name into an IP. The order a computer does this is by host, WINS, DNS or host, DNS, WINS depending on what OS you are using or how it has been configured. What this means is, when your computer is given another computer name to connect to it will check its own files (the ones we will edit) first, if that fails it will ask the DNS server, if that fails it will ask the WINS server. A quick description of what these actually are .....

Hosts: A few files held on your workstation which contain a list of computer names and IP addresses used for resolving names to IP addresses for both WINS and DNS names.

DNS: 'Domain Name Services' or 'Domain Name System' (it changes depending on where you read it) is the system used to turn names like 'www.yahoo.com' or 'www.blueyonder.co.uk' in valid IP addresses. Keep in mind these names are only for our benefit, so we can remember them easily. A computer will always resolve these names into a unique IP address before making a connection. Try putting 209.191.93.52 into your web browser. ;)

WINS: 'Windows Internet Naming Service' This is an older system used by windows, its very similar to DNS in that it still resolves names to IP addresses but it was for NetBIOS (pre windows 2k). This is still commonly used in windows but is really only there for backward compatibility for services on older operating systems that require the use of WINS names. A WINS name would be something like 'PC1' or 'PC2'.
 
Now back to editing the files. The two files you want to edit are ....

C:\WINDOWS\SYSTEM32\DRIVERS\ETC\lmhosts.sam
C:\WINDOWS\SYSTEM32\DRIVERS\ETC\hosts

The first file 'lmhosts.sam' needs to be renamed to 'lmhosts', the 'sam' extension just means 'sample', there are examples inside the file (open with notepad) but it is ver simple to setup. lmhosts mean 'Lan Manager Hosts', an example of what a basic lmhosts file would look like .....

******************************************** (ignore this line)

192.168.1.1 PC1
192.168.1.2 PC2
192.168.1.3 PC3
192.168.1.4 PC4

******************************************** (ignore this line)

There is more that can go into an lmhosts file but you shouldnt need anything more than the above for a basic peer to peer network.

The second file is the 'hosts' file, this one is used to resolve DNS names. Your best bet is to make a clone of the lmhosts file as you only want your own computers names to be resolved correctly. A hosts file could look like ...

******************************************** (ignore this line)

192.168.1.1 pc1 #or if you want to add you own domain name ...
192.168.1.1 pc1.mydomain.com
192.168.1.2 pc2
192.168.1.3 pc3

******************************************** (ignore this line)

You can have the same IP mapping to different names if you like, but make sure your own computers names are entered correctly. Also remember that these are static entires and will not change unless you change them manually. Because if this you should always assign static IP's on your internal network, which you should do on a small network anyway, that way you know exacly what is going on. Your computer will ALWAYS check these files before asking any server to resolve a name. If you want to test this out, try making an entry in the 'hosts' file with the name of 'www.blueyonder.co.uk' that maps to the IP '209.191.93.52'. Then open a web browser and go to 'www.blueyonder.co.uk' and see what happens. :)

With your host files edited correctly on each workstation, traffic intended for your local network will never go through your internet connection.

Just as added info (which is handy to know) it is useful to know how your computer knows which NIC to use to connect to other computers on your local network. How does it know not to use the NIC with the modem attached to get my to my kids computer? Well this is very smartly done. Try opening a command prompt (START > RUN > CMD) and type 'route print'. This will show you what is called a routing table, this is how your computer know where traffic is sent and through which adapter. Your NIC attached to the modem will always be assign a public IP, this being an IP that is valid to anyone connected to the internet, your local NIC should have a 'Class C' private address. A Private address is on the 192.x.x.x addressing scheme; these IP's are NOT valid out on the internet, they are only use on internal network. For example, you would address all of you internal computers 192.168.1.1, 192.168.1.2 etc then you add a router which has its own private address and a public address to act as a 'middle man' between your PC's and the internet. It was just a way that was come up with to stop us running out of IP addresses (pretty cool idea me thinks).

When you assign static IP's internally, you only need an IP and Mask. A default gateway and DNS server is not required (there are exception but you wont be using them). When you are assigned IP info by your ISP, an IP, Mask, Gateway and DNS addresses are assigned to you.

This is what your computer does when making an IP connection (in basic human terms). Have a look at your own computers routing table at this point.

Making an internal connection...

Connect to \\PC2
Who is PC2?
Check host files first
Found it, PC2 is 192.168.1.2
Hmm I have two NIC's, which one do I use?
Check routing table, 192.168.1.x uses NIC number 2
Connect ...

When connecting externally...

Connect to Yahoo!
Who is Yahoo!
Check hosts files
Not found
Query DNS server
Found it, DNS server replies that Yahoo! is 209.191.93.52
Hmm I have two NIC's, which one do I use?
Check routing table, 209.191.93.52 is not on my network, use the default gateway
Default gateway is on NIC number 1
Connect ...

Thats roughly what happens lol. As you can see, once the name has been resolved, the computer can work out the correct interface (NIC) to use.

Now onto what you said about when you log in you are assigned to one modem, when the kids log in, onto another modem, etc. You can do this but it would take a bit more complicated setup. Using a server to change your default gateway depending on which user logs in.

I apologise for dribbling on for ages, I was in a typing mood and used your question to get a bit info out there. Hopefully yourself and other find some of it useful. Its always a good thing for people to have a good idea what going on with there compuers. :)

Sorry the post was too long, I had to split it into two. lol

EDIT: lasor mate, if anything I've said doesnt fir what you want to do, let me know and I'll try to help out. :)
EDIT: Its parsing links, even though I told it not to.
 
Last edited:
Hi Keepgood2006

Thank you for the excellent comprehensive response..I have a quick read through and it sort of makes sense, however I will have a proper read through later tonight.

Thanks again
 
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