2 IPs in 1 LAN card

Hello, everybody, i am a newbie here, well i have a simple question here.. I have 1 LAN card in my pc, which has a public IP of its own, HOW-to add another IP to it? i think i saw some article by using a command-line..but I have forgotten the link

can anybody please help? thank you.

You didn't say what OS you use, but Providing your using XP go into Network Connections from Control Panel and right click the entry for your NIC (probably called Local Area Connection) and click properties. Now double click the entry for Internet Protocol (TCP/IP)....

Now the first thing to be aware of is I don't believe this way will work with DHCP, so on the first page I think it has to be set to static ('Use the following IP address') Hopefully on this first page you'll see an IP address, subnet mask and gateway. If your ISP allocates an IP address then this way probably won't work. There may be another way, I don't know.

Now click Advanced and at the top where it says IP addresses click add and add your second address. It should appear below your first one. Click OK etc when your done.

Couple of points:

I have no idea how well this will work, as I've never had the need/opportunity to add multiple IP's to one card. If the LAN that the second IP connects to goes off to any other networks then you'll have to add routes (this is probably unlikely but thought i'd throw it in)

If it doesn't work then (depending on your OS) i'd try getting a second NIC and installing that. That generally works very well.

Also, you say your NIC has a public IP so you need to make sure you have a software firewall installed if you don't already.

Phew think thats everything!

S

thanks for your detailed explaination i really appreaciate it!

very good info, and a great post. Thanks a lot for the info DuckIT.

np

Awesome info! I just found a great use for this today and used the search function to find this thread again.

Thanks DuckIT

I actually have another question about this though.

Here is the situation, I'm using my computer as a router for the other 2 computers in my room.

So my first nic has an ip address from the cable modem and has internet connection sharing enabled. (I'm running Win XP). My second nic is connected to my switch in my room.

Now using the above post I assigned my first nic a second ip address to use locally with the other people in my apartment so that I can run a ftp and they can download off of it without having to go through the cable modem. (Which works great).

My question is this: A few minutes after I added the second ip to my primary nic, it seemed to have a problem acting as a router for the rest of my computers (which has always worked without a problem before). Why is this? Is there a way to be able to have internet connection sharing enabled and have the second ip address on the primary nic and have everything work?

Noooo not internet connection sharing....ARRRGGHHHH.....the pain, makeitstopmakeitstopmakeitstop.

Sorry but ICS has that effect on me. Used it a couple of times and had nothing but trouble with it. Personally i'd try and get a proper router for this.

If you do a search for internet connection sharing on Google you should find some good guides on setting it up. Its been ages since I used it. A quick search revealed this link "http://www.annoyances.org/exec/show/ics_2000" which looks about right.

As far as I remember though you shouldn't need multiple IP's on one NIC with ICS. I think thats where you may be going wrong. I think you just have the inside card on your inside range (192.168.0.1 or whatever) then your outside card getting the external / legal address (66.102.9.104 or whatever) from your modem. But as I say, its been a while!

S

okayy first things first. YOU SHOULD NEVER USE ICS IN AN EXISTING NETWORK WITH WINDOWS 2000 SERVER DOMAIN CONTROLLERS, DNS SEVER, GATEWAYS, DHCP SERVERS, OR SYSTEMS CONFIGURED FOR STATIC IP . please DISABLE IT.

well i do know with windows 2000 and above you should be able to assign 2 different IPs on the nic but this is neccesary when you have two diffrent Lans and you want some security. I did this some time back but when you assing teo differsnt Ips there is a way you should assign your client pcs IPs according to the Ips on your card. read about sub net

He's using the machine as a router for 2 other PC's. I'd say he'd be fairly unlikely to have a domain setup. And ICS has to be on a system with static IP. Its not really gonna work very well if the ICS server keeps changing its IP address

S

Ok, here's the deal.

First, I'm a girl... not a "he" which I thought was obvious from my name.

That being said.

1. I've used ICS for almost a year to give my other two PCs internet without a problem and I'm not about to disable it for no reason when it works perfectly fine. Also my motherboard has two onboard nic's and I already have a switch. So I see absolutely no reason to go out and purchase a router when I want others to be able to connect to my computer from the outside and I don't want to mess with port forwarding.

2. I'm not using the multiple ip's on one card for the ICS. As I stated in my earlier post, I'm using the multiple ips so that people in my apartment (who are on the same cable modem and switch) that I am on can access my ftp without going through the cable modem, thus giving us a bandwidth of 10Mb/s instead of 20Kb/s upload provided by our ISP. So if I set up a non-routable ip, once the switch gets sent a request for a 10.x.x.x ip, it won't try to send it to the cable modem, instead it will just look for it on our "local network" in the apartment.

Now back to the problem:

I could get both of these two things (multiple ip's on one card and ICS) to work separately from eachother but not together. My two other PCs behind my computer were getting 192.168.x.x ip's which I would expect them too, but it appeared that the reason that they couldn't reach the outside world was because they weren't being "shared" with the correct ip. Instead of being "linked" (for lack of a better term) to the 65.x.x.x ip address that reaches the outside world, they were being linked to the 10.x.x.x ip address (which as I stated before is a non-routable ip), so of course they couldn't get to the outside world.

The fix:

After entirely too long of tyring to fix this, I got the bright idea to try to remove both ip's from my primary card, then add the 10.x.x.x ip first to my primary card and enable ICS (even though at that point I didn't actually have "internet access") and then add the 65.x.x.x ip. Which surprisingly worked rather well.

What 2 IPs might do?
Can you actually do anything special with it?

Apologies on the 'He' thing Shedevil. So used to seeing a name that has nothing to do with gender that I don't even check it. Soreeeee!

Okay now I understand!! Sorry, got confused there and just guessed all the machines would be on the inside of the ICS machine without reading the whole post properly again. My big doh!

That some kind of special deal you got with your provider? Only ever seen cable modems tied down to a single MAC address, never seen them shared like that before.

ICS: Yeah fair enough. Sometimes you have good luck with it sometimes you don't. I just found it buggy is all. I was trying to get port forwarding & games etc to work with it though.

Ragnar: 2 IP's is just so one machine can communicate on 2 subnets. Its not something you'd have to do often and doesn't give anything special other than the above function.

S

It's ok, just wanted to point it out is all

We get 4 IP's from our ISP for our apartment, it's included in our rent. Otherwise it would be like $45 for cable internet then $5 for each extra ip.

Thanks for the info DuckIt...