I have kind of a strange problem.

Here's the deal: I have a network that every computer and printer (as well as the server) that is connected to the network on a permanent basis uses static IP addresses.

Occasionally there are visitors that need Internet access and the owner wants to provide it to them via a hard-wired connection on their laptop.

There is a Linksys switch behind the router (also Linksys with a single port feeding the switch) that apparently does not have DHCP turned on.

My question is: Is there anyway to determine the IP address of the switch so I can go in and turn DHCP on?

I've tried IPCONFIG /ALL and I still can't see the switch. I've tried the tracert command as well to no avail.

I suppose I can default the switch but this thing has got me wondering if there's a way to determine IP addresses of a particular device on a network.

Bobby

a switch wont assign a IP

you say there is a router there you need to turn DHCP on in the router

Yup, the router is the DHCP server. You can turn DHCP on with the static IP's and it will assign an IP to the laptop assuming it too has DHCP enabled. I would check to see if it isn't on at the router, that's the factory default.

192.168.1.1

-Hal

Do an IPConfig and find out what the gateway address is.

Larry makes a good point , a lot of times I see the LAN address changed if there is a static scheme in place

yep DHCP is turned on in the router. And I know it works because I can log onto it with a wireless connection on my laptop. The problem with the wireless is certain parts of the building get lousy signal strength and the owner doesn't want to go to the expense of buying more routers just to provide a courtesy for occasional visitors.

The Gateway address is the router address where you will have to go to turn on DHCP.

When you are connected wirelessly open the wireless connection status box and click spport. It will tell you your adress/subnet and the gateway.

Type the gateway address in a browser and you will get the router login screen. It's password protected.

The problem with the wireless is certain parts of the building get lousy signal strength and the owner doesn't want to go to the expense of buying more routers just to provide a courtesy for occasional visitors.

Not additional routers, they need an access point, they just plug into a network jack. Many can be configured as a repeater also. They are less than a couple of hundred bucks. Bet if you strategically locate one it's all they will need.

-Hal

Not sure if this helps, but for Motels, the Wireless Access point I prefer for setting up a Wireless Distributed network are Teltronics TT2400. They're not exactly cheap, but you do get what you're paying for with these babies.

Or as Hal said, if you connect a wireless router to the network by a LAN port (NOT the WAN port), you can use that as a wireless access point. A netgear MIMO wireless G should work just fine...and since G is on it's way out in favor of N, you can probably get one for a good price (A G wireless will work just fine by the way).

Just be sure that you re-assign the IP address so that it doesn't cause a conflict on the network!

Thanks guys. I'll tinker with it the next time I have a few spare minutes.
The owner is in no hurry so if I can't get it to work he'll just wait until he needs the IT guy to come in for something in the future.

Needless to say I don't play around with switches at all. This was just something they wanted me to try because I've set up the network connection on several new computers they bought in the past and this really should have been a simple task.

I suppose I can default the switch but this thing has got me wondering if there's a way to determine IP addresses of a particular device on a network

You might try this: advanced ip scanner

https://www.radmin.com/products/utilities/ipscanner.php

What model switch?

The low end Linksys switches are unmanaged, don't speak IP, and don't have an IP address.

The managed switches generally have a serial port that you can connect to, assuming this it isn't password protected, which would allow you to find the IP address, if one is configured.

Thanks TDS. That's exactly what I was looking for. :thumb:

I'll have to get the model number of the switch tantivity. I'll try to go by today and get it.

Edit: I went by today and I was wrong about the brand of the switch. It's a Netgear Prosafe FS116. Which according to my research is a low end product so I don't think there is any kind of IP control in it.

that switch is a dumb one. completely unmanaged.

The IP scanner is nice, but it wont let you find all of the devices on a network, just the ones responding to PING. All the scanner does is ping every IP in a range that you provide. It won't let you find devices configured for an IP outside the range you specify. The best way to find all types of devices using all protocol types (provided they are sending out something) is with a sniffer or packet capture device. The better ones are hardware based and will show all packets. The linix ones for the most part wont catch the error/runt/collision packets that will indicate a problem with the network unless the card it is working with can be set not to filter them at the hardware level prior to passing them up the stack to the application. You may get a flag that it saw an error or runt, but not the content which lets you find the problem.

edit was to change a wrong word.

Oh and if you turn on DHCP, make it for a range that doesn't have static addresses. the router may not know they are there if it is rebooted and hasn't yet seen traffic for them if they are off at the time. This can lead to IP conflicts.

Thanks for the info. I've used sniffers on my wireless network when I thought someone was hacking into it but I never thought of one on a wired network.