Software NAT require 2 nics or 1 for cable modem?

[bigjon]

I know 1 nic is fine for a NAT with DSL (I'm thinking of going with Sygate or NAT32), but what about cable? Are there security risks using 1 nic on the NAT gateway?

 

[BCYL]

The reason you need 2 NICs for cable modems is because you need one to connect the cable modem to your PC, and the other to connect to the LAN.

You should also need 2 NICs for DSL, unless the DSL modem is connected thru the USB port.

How exactly are you connecting your DSL with 1 NIC though?

 

[bigjon]

My friend with the DSL setup I referred to connects his external DSL modem to the uplink of his hub, then from there to each computer on his LAN. Instead of a proxy he uses a NAT, so it operates as a gateway (on the other computers in his network he sets the IP to 192.168.x.x and the gateway to 192.168.0.1 - the NAT server's IP addy). Hope this makes sense

I'm just wondering if I could do it this way or if it'd be a problem with cable.

 

[pdo]

That external modem you're refering to is probably a Cisco 675 which has a built in router that does NAT(network address translation). On cable if you're not sharing lines than you'd probably need a firewall software like ZoneAlarm. I hope this clears up for you cuz you're sure confusing as hell . J/K

 

[BCYL]

Yeah... with normal cable/DSL modems you can't just connect it to the hub unless you have enough IPs for all the PCs in your network... unless the modem goes through a router or has a router built-in, it won't work... hope this explains it...

 

[Engineer]

NAT32 is a program that claims that it can share a cable/dsl connection even if only one ethernet card is available. I think this is accomplished by using NAT32 as a DHCP/DNS server for the other PC's. I've used NAT32 with a two NIC PC and it was very nice (A hardware router is better...IMO)...

NAT32 page

Good Luck

 

[bigjon]

-paldo,
I don't know what kind of modem he has but you're probably right(definately about the confused part ).

Engineer,
I'm going to try either NAT32 or Sygate (another NAT-based software). I think I'll try them with both 1 NIC and 2 NICs.

I really want to be able to keep one PC outside the firewall/NAT (I have 2 IPs), and still be able to play multiplayer games with PCs inside the LAN. I know that's next to impossible to set up through a proxy, so I'm hoping a NAT will be somewhat easier. On the other hand if I keep all the gaming PCs inside the LAN it's harder to play Internet games. :Q

Thanks for all your help!

Dazed and Confused,
Jon

 

[anton]

I have Cisco 678 ... I put two nics in to my PC and used Sygate, but when ICQ didn't want to connect on the network pc on linux, I set up w2k internet sharing ... and it works better then Sygate ; )

as for security ... I can't connect myself to my computer as server us my internet IP ... so , if you don't need to use it as server, everything will be ok ...

and I have a question how do I allow other ppl connect to me with Cisco 678 ? .. should I route or something ? ... and how ?

Thank you,
bye.

 

[pdo]

Anton Why would you do that if the Cisco has a built in router which work better than W2K ICS. And if you want to run an FTP server I assume. Than just use the command set nat entry add "your local IP address" "port number" "your real ISP address" TCP

without the quote though.

 

[anton]

2paldo :

the problem is that as I understand , I can't connect my router to the hub by the agreement , because then I'll have to buy multiple IP's ...

and thanks for the tip on routing

 

[anton]

I just did

set nat entry add 10.0.0.2 7 162.3.40.12 tcp

and it doesn't work ;(

thank you,
bye.

 

[pdo]

Your ISP is bullshittin' you. You don't need multiple IP when using a Cisco router. I have some infos on the Cisco 675 which is more or less a 678. That command about port forwarding I'm giving you might not be accurate. Here's the link that can get you going on some questions you might have.

link 1

link 2