IP Address in use by another

I would turn off your router and turn it back on again and reboot your Mac.

If you still get the issue. Give your mac a manual IP address using these settings

IP 192.168.1.10
subnet mask 255.255.255.0
router 192.168.1.1
dns 192.168.1.1

then try pinging 192.168.1.102 if you get a response then you would know for certain if you have a device on your lan using that IP.

BTW if your using a wifi router have you secured it? Maybe some unofficial person is using your connection? This would be the most likely explanation as to why another device is using your IP address.

Hi Tim...

To do this look in your routers DHCP server

settings

for this feature.

WHAT?

Could you please explain it a little more? Am I
suppossed to have some kind of control panel or
someting where I can manage such kind of things?

Thanks!!!

Most home/small office routers have a web page built into them at their default address. (for example, Linksys routers typically have a default address of 192.168.0.1 or 192.168.1.1) If you enter that address into a web browser (Safari, Firefox, whatever) you should go to that page. The system will ask for a username and password; Linksys will usually have a blank username with the password set to 'Admin'. (I'd change that if I were you...)

Once in the router web page, you can set many items. Among these are the DHCP settings. You can set DHCP to allocate all addresses in your local network (that is, 192.168.0.1 through 192.168.0.254, except, of course, the IP that the router itself uses, which is usually .*..1; .*..0 and .*..255 are special and should never be used in a class C net) or only some of those addresses. The others may be excluded or reserved. If they're excluded, then the router knows nothing about them, and you're free to use them as the IP address of any machine you want. You can do this by entering that address into the TCP/IP info section of the machine in question, whether Mac, Windows, Linux, a printer, whatever. If the address is reserved, though, it is linked to a particular MAC address. In other words, only that particular machine is supposed to use it. Typically servers and heavy-duty printers have reserved IPs. They'll get that IP automatically as soon as they contact the router.

If you have two machines on the net which have the same IP, they will conflict. Typically you get two machines with the same IP if:

1 an IP was reserved, but someone typed in that IP into a different machine

2 someone typed in the same IP into two different machines

3 an IP was neither reserved nor excluded, and someone typed it into a machine... and because it was neither reserved nor excluded, at some point DHCP handed that IP out to another machine.

The best way to avoid this is to not type in IPs into machines that don't need fixed IPs, and to make sure that any fixed IPs you do type in are excluded from the DHCP pool. (Do NOT type in a reserved IP, this almost always leads to trouble.)

From the sound of it you have at least two machines which have the same IP. This will never work.

And, oh, by the way... don't put two routers which are configured to set DHCP onto the same net. Both will try to hand out IPs. This is bad. I'd turn one router off, go to the other, turn DHCP off, then turn the other router back on. AirPorts are routers. Macs set to do internet sharing are routers.

All,

The best solution of all has not been mentioned yet. Most routers allow you to assign specific IP addresses to specific machines while still using DHCP to make the assignments. This is generally much more desirable than using static IP settings so that your local network computers also get current DNS and gateway IP addresses from DHCP as well.

To do this look in your routers DHCP server settings for this feature. To use it, you simply enter the "MAC" physical Ethernet address (i.e., the xx-xx-xx-xx-xx-xx formatted address) and an IP (xxx.xxx.xxx.xxx) that you want that computer to receive. Once set up, a machine will always be assigned the same IP by the DHCP server. You can get ethernet addresses from your machines by: printing a test page from network printers; using Network Utility or ifconfig command on Mac OS X; using the winipcfg command on Win 95/98, or using ipconfig command on Win 2K/XP machines.

And lastly, once you have assigned a "reserved" IP to all of the devices on your small network then you can restrict your DHCP server's address pool to only those addresses thereby making it slightly more difficult for a neighbor to join you wireless network (if this applies).

Hope this helps,

Tim

17 PB G4, Xserve G5x2, XRAID 2.5TB, 20 iMac G5, 17 iMac G4 Mac OS X (10.4.3)

Tom:

I did as suggested and it worked perfectly. My problem was similar: the printer, an HP DeskJet had the address. I turned off the router and the Computer and waited a little. After a minute I turned on every thing, and after a few minutes everything was OK.

I have a small office, with as much as 10 computers connected. The router is a SISCO 1700 series.

Hello Tom

By default a linksys router assigns DHCP IP addresses starting from 192.168.1.100. To prevent this conflict happening again give your printer a static IP address 192.168.1.50.

It is good to know the problem was with a printer and not a potential hacker.

Okay... now you check to make sure that the printer has a fixed IP. Typically IPs can be set using the printer's LCD control panel. Make sure that the printer has the correct address. Make sure that your computer's address is on the same network; if your computer is on the 192.168.0 network and the printer is on the 192.168.1 network, you're going to have trouble printing.

Hello Jose -
A few messages above this one (click 'view all'), there is another message that reads:
By default a linksys router assigns DHCP IP addresses starting from 192.168.1.100. To prevent this conflict happening again give your printer a static IP address 192.168.1.50.

Does that work for you?

Hi-
Have you looked at the manual for your printer to learn how to configure it with the proper IP address? Is this printer truly 'network ready'?
Lots of manuals here:
http://www.epson.com/cgi-bin/Store/support/supDetail.jsp?BV_UseBVCookie=yes&info Type=Doc&oid=14430&prodoid=11356&category=Products

There should be a few documents there to help you.

[snip]

I found I could print a test sheet (a configuration
sheet, to be exact) where it tells everything about
the printer: Card Type, MAC address, IP, etc...

IP address: 192.168.73.2

This address is not part of the subnet your Mac is on. Your Mac will not be able to see that address, and therefore will not be able to use the printer.

It would be a good idea to either change the printer's address to the Mac's subnet or the Mac's address to the printer's subnet, whichever is easier.

An IP address consists of two parts: the network address and the host address. For a class C address (such as the addresses in use here) the network address is the first three octets. In the case of your printer, those are 192.168.73. The host address is the last octet. In the case of your printer, that's 2.

The last time you said that your Mac was on 192.168.1.something (I forget the exact address) which would put it on the 192.168.1 subnet... which won't talk to the 192.168.73 subnet unless there's a router or a bridge between them. You don't want that. You want all your stuff to be on the same subnet. Life is a lot easier that way.

Subnet mask: 255.255.255.0
Default Gateway: 192.168.73.1

This means that the IP address allocated to whatever device is talking to the rest of the network is 192.168.73.1. If you don't have a router with this IP, then the printer can't talk to anything else on the network and nothing else on the network can talk to the printer.

[snip]

I tried to crerate a new subnet in the router with
this settings:

Don't do that. Reset your router to factory settings. If there's more than one router or bridge on the net, take off all but one.

Your net should look something like this (Warning: bad ASCII art ahead)

|----P
I---M---R---|
|----C

where I = Internet, M = Modem, R = Router, P = Printer, and C = Computer.

You should have a signal coming in from outside to your modem, which is connected via an Ethernet cable to the WAN (usually labled 'Internet') port of your router, which in turn is connected via one LAN port and an Ethernet cable to a printer and via a different LAN port and another cable to a Mac. (How you're getting Internet in, whether cable, DSL, ISDN, multiplexed POTS, whatever, is irrelevant so long as the modem you're using understands the input and has an ethernet port for the output.) You really should use category 5, 5e, or 6 cable to connect your various devices. Category 3 cable will usually work, and its top speed of 10Mbps is far faster than today's Internet speeds, but if you use your net for other things you may find that speed restricting. And tomorrow's Internet speeds may exceed it. Cat 5 cable can handle 100Mbps, and 5e and 6 are faster yet.

The default settings on home routers are to have one port (the WAN, or Internet, port) set to receive signals from the modem and to send signals back to the modem. This port will be on a different subnet than are the other ports on the router. This is how it's supposed to be. The majority of cable and DSL Ethernet-based modems sold in the US have a router built in and will generate there very own little subnet, on which there will be only two hosts: the modem and whatever is on the other end of the ethernet cable, in this case the router. The gateway will be the modem. The router will generate a subnet of its own, which has the router as the gateway, and anything plugged into a LAN port (or, if the router is wireless, anything connecting via a wireless card) being set up to be hosts... as long as they're set up to use the proper subnet.

Linksys routers are usually set to have the first ten host addresses (x.x.x.1 through x.x.x.10) excluded from their DHCP pools, so that usually your computer's address will be x.x.x.11. The router itself is usually x.x.x.1. This leaves x.x.x2 through x.x.x.10 available for you to use to set items with fixed IPs, such as printers which don't do Bonjour/Rendezvous/zeroconf.

In your case, assuming that you're using a network address of 192.168.1, the router should be 192.168.1.1, the computer should be set by DHCP to be 192.168.1.11, and you can set the printer by hand to be 192.168.1.2. You can use a network address of 192.168.x, where x is 0 through 255, to set up a class C subnet. It is a very, very, VERY bad idea to use anything other than 192.168.x for a class C home network. Doing so may cause you to be ToSed by your ISP. Don't do it. There are class A and B subnets you can use; Apple uses a class A, 10.x.x.x, for networks attached to AirPort Base Stations, for example. However, we're having enough problems with a simple class C, I really don't think that messing around with an A or a B is a good idea right now.

Hello Jose

As your cisco router is using DHCP find out what the range of the dhcp pool is and then manually assign a static ip address to your HP Deskjet.

I am having the same problem. Did you managed how to solve it? Any suggestions?

He solved the problem as he discovered his printer was using an IP address that his G5 wanted to use. The conflict was removed.

Jose welcome to the discussions can you list your Network setup what router you use how many computers on the lan and any other network devices you have?

Hi Tim, Jose and the other in this thread...

I'm searching for a similar answer. In fact all that is said here is likely to be of great value in a inminent future... 😉
But before I can continue with my printer setting (wich I'm trying to cnnect via GIMP-Print -printer is EPSON 3000-).
All of you here talk about telling the printers IP or even giving it a static IP so it won't conflict whit another devices...

BUT,

¿How come I do that? I'm going nuts looking around and asking people around me and no-one seems to know...!

All I need (by now) is knowing how to tell my printer's IP address, so I can manually put it in the "Printer Setting Control Panel" and put it to work...
I can tell my 3 machine's IP addresses (wich are connected to a router which gets the Internet line from the wall DSL socket...) by looking the Network pane in System Prefs (that is right, isn't?), but I'm blind when it comes to tell the printer's...

I hope some of you could help or "address" me in this tip that's almost driving me paranoic! 😉

Best regards amigos!

J.