Multiple private networks, 1 internet connection.

**Darrell1** · April 1st, 2005, 02:21 PM

My office is in a building with 3 other businesses. We all share 1 internet connection. The problem is, we can all see each others shared files. This has been fine as we all trust each other, but one business is getting bigger and bigger. We would all like to protect each network, but still share the internet connection. How do we do this?

Can we password protect our networks? Do we need multiple routers? Dispite a lot of searching, I cannot seem to find a solution. How does big business do it? Obviously management does not have its files viewable with everyone in their building....

Thanks for any help!
Darrell

**jkrohn** · April 1st, 2005, 02:24 PM

Get a router and divide your network into different subnets. This will keep the networks seperate. Lots of ways to implement this.

Jkrohn

**joshwilson_1** · April 1st, 2005, 02:55 PM

Depending on how much traffic and the level of security, you might think about getting a Cisco switch to create virtual networks and not allow one network access to another.

**Sixpac_XP** · April 1st, 2005, 03:13 PM

Are you all on one big flat lan?

Are you running any kind of domain (eg Windows 2000/03 domain).. are they?

**Siliconjunkie** · April 1st, 2005, 03:18 PM

Sounds like they are one flat LAN if they can see each other.

Not sure what a domain has to do with it. This is a bad setup no matter how you slice it.

**Darrell1** · April 1st, 2005, 03:51 PM

Excuse my ignorance - I'm not an IT professional - maybe I will be by the time I get this accomplished.

We are all using a Netgear Fast Ethernet Switch and a Cisco Pix 501 Firewall. We are not running any type of server software. We're not even sure what that would do. Basically, we can all see each others files, printers, everything and we just want to have the separate, secure networks yet share the internet connection.

Darrell

**joshwilson_1** · April 1st, 2005, 07:19 PM

That kind of switch is not going to provide you with the ability to seperate the three networks from each other. The Cisco Catalyst 2950-12 is about $450 and would allow you to specify which ports you wanted to communicate with each other. This could seperate the three networks from each other.

**excuzzzeme** · April 1st, 2005, 08:04 PM

Perhaps the easiest way would be to add another router ( for one of the networks) and turn off DHCP at the router. Create a new network address for each network, use the new router as your gateway address. Configure the new router to use a gateway of the old router. (You can extend a network with mulitple routers, each one with a different IP add and different workgroup. I have been forced to do this due to the buildings, and business arrangements in our area). May not be the best idea, but it works fairly well without anyone being able to see each others networks

**Siliconjunkie** · April 1st, 2005, 08:14 PM

Well, the problem with just using a router (that does not support ACLs) is that they will still be able to route between each other. edit: I see what you are saying, I think.

The best answer IMO, would be to setup a linux machine doing routing, then use IPTables to create rules to not let A talk to B and B to C and soforth, but let all of them goto the internet.

If you have some money to spend, almost any firewall that will support 4 interfaces will do the trick.

If you are unsure about this, the best thing to do is to hire a consultant to do it and learn as much as you can from them.