Strange Home Network?

[SpaceWrangler98]

One of my friends just got a cable modem (Roadrunner ISP) and paid some guy to come network all there computers to share internet access. I told her to buy a router or mentioned Wingate or Sygate, but she said this guy didn't need either. Apparently he hooked the cable modem into the hub along with all three other computers, and it seems to work. So I asked if they are paying for any additional IP addresses from their cable company and they assured me there not. I also told them to check there local IP addresses and there all diffrent, so it doesn't seem as if they have any kind of Proxy or NAT. It seems to me the only conclusion would be that the cable modem is acting as some kind of DHCP server but that doesn't make much since to me, since the cable companys try to offer additional IP addresses. Does anyone know how this is capable of working?

[jfinnan]

DOCSIS cable modems can be configured to support from 1-16 attached devices. Some cable operators configure modems to support only 1 device, while others allow more. By only allowing one device, the operator can charge you more money if you choose to have more than one PC connected.

This particular user should consider himself lucky that his cable operator is being so generous. However, having some kind of firewall/router is much better.

Also, it is possible that your friend may have one of the PCs acting as a Proxy server to the other PCs. There is just too little info to know for certain what she had done.

[SpaceWrangler98]

Well I know they don't have one of the computers running as a proxy because when i asked her to find out all the computers' IP address on the local network, none were private. And by going to www.geektools.com (http://www.geektools.com) and running a whois they were all isued by their ISP. You brought up another question though, since they all have file and printer sharing turned on doesn't this leave them quite open for attacks since there is no firewall. Thanks for all the info though!

[glc1]

Since ur friend isn't paying for additional IPs, multiple IPs must b included by default w/ their service (I've heard of 1 cable ISP that offers 3 IPs, I believe, w/their service but can't remember which 1). Otherwise, the network tech just "barrowed" the needed IPs. If this is the case, the customers that r assigned to the "barrowed" IPs (if any1 is) will have probs getting on line.

[This message has been edited by glc1 (edited 10-26-2000).]

[Storm90]

If it is borrowing Ip . Don't be surprised if one won't connected, When the other ones on. Due to it might borrow its. My neiborgher tried the same thing and that is what happen to him. He ended up buying another IP.

[freeek]

I am a roadrunner senior tech and there is no rr office that is just giving away 24. ip's. Your friend must be using our 4100 USB modem. The 4100 has a usb for the main comp and a cat 5 for a uplink to a router or hub. The older 3100 only have a cat 5 port on the back. So if you want to run many machines you will have to uplink the 3100 to a router then to a hub.