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IP addresscan


bigjim

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Simple answer, No.

 

More fuller answer, behind a Router, like the wireless one many of us use, several devices will appear as one IP Address to the world. It is a lot of magic.

 

If two devices pop up with the same IP address on the local LAN (which can be the wireless) there was be squawk messages and things won't work. This rarely happens unless someone sets the IP address of a device. Normally, the magic in the Router will assign IP addresses to devices so there is no conflict.

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On your local network sometimes you will get two devices with the same IP address. It is not supposed to happen, but it does. Normally it is because one device has the IP address locked, maybe a wireless printer, and the router does not know and assigns the address to another device. This can be a real mess when the one that was locked was set up with a previous router that had a way to mark the IP address as used, but that router was replaced with one that does not have that ability.

Another more rare version is where a computer jumps between local WiFi access points and tries to keep its old IP address. It is not supposed to work that way, but it happens. This is like moving to a new house and trying to keep your street address.

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Simple answer is that IP address is like your telephone number. In your own house, you can have multiple extensions that can use that same number but no one else on the network will have that same number.

 

To answer the second question, two devices can have the same IP address in your home network. Just reboot or refresh the connection and that problem will most likely go away. Just a minor glitch that happens sometimes.

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Your IP address is like your place in the queue when you are on hold with one of those annoying machines that start you with you are number three in the queue, then in two minutes says that you are number two in the queue, and leaves you there all day.(Kidding) As long as you hang on, your place in the queue stays the same as it moves closer to being answered. If you hang up that number is assigned to the next person. When you call back you have a different number.

 

When you connect to the Internet your Internet Provider assigns your router an IP number, you keep that until you disconnect. It is a "dynamic" IP address as it changes every time your router connects. Most home users do not need a "static," or permanent IP address number. Those that do need a static address, need no explanation.

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I sort of get it. According to the park owner here he is getting the explanation from the local company that we are having a clash of duplicate ipaddress' on his wifi set up. I think he is trying but is not skilled at this and is skeptical of the explantion. He seems to think it is tied to someone here the park that is leaving thier computer/printer on line 24/7 that somehow is showing the same ipaddress. I know at least a couple or more are likely using verizion phone/hotspot or something through their dish or the like. It is not causing me a lot of issues but is slightly irritating. The park owner is conceintious about his service being available even though he uses it marginally himself.

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I'll try to keep this,brief. Every networked device has a unique identifier called a Media Access Control (MAC) address. No two devices ever have that same address (not to be confused with an IP address). When the device is first connected to a network, whether wired or wireless, it will broadcast a message saying "I'm on the network and I need an IP address and here is my MAC dress". The router on that same network has a table containing all the IP addresses it is allowd to assign as well as all the IP addresses currently in use. When the router receives a request it looks at its table, finds an IP address that is not in use and then offers that to the device. The device excepts and the router records that MAC and IP address combination in its table. It is the unique MAC address that assures IP is not duplicated. Called Dynamic Host Configuration Protochol or DHCP.

Theoretically you should.never have duplicate addresses. However, you can also manually assign an IP address to a device. This is where duplication can occur. If you mannually assign an IP to a device that is already in use you will (should) get an error message stating "Duplicate IP address" .

Pretty much in today's environment you should never manually assign an IP address. Even if a specific IP is needed for a particular device that can be handled by adding a "reservation" in the router so that device always gets that IP and the router knows it.

There's lots more but that's the short of it.

If the parks network is getting duplicate IP ddress the first suspect is a miss configured router or someone has plugged thereown personal router incorrectly, plugging the LAN port into the network instead of the WAN port. This would be a wired connection not a wireless connection.

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The same IP question can get complicated, you can't have the same IP for two computers on a LAN but there are several ranges of IP addresses that can be duplicated as long as they only appear on a LAN, RFC-1918 discusses this and is likely more than you want or need to know.

 

Fixing the issue on your LAN is doable but it will take a bit of skill so you might want to look around for someone with some network skills. What is likely happening is that someone has configured their computer to use a specific IP address that is also one that is used by the DHCP (automatic ip address assignment tool) and the DHCP server is trying to give that address to a second computer. The fix is to find the IP address that is causing the problem and block it in your router so it no longer works. That will force the person misusing it to change their address. You might have to bump them a few times until they quit abusing the LAN and use the DHCP system to get their address.

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("What is likely happening is that someone has configured their computer to use a specific IP address that is also one that is used by the DHCP (automatic ip address assignment tool) and the DHCP server is trying to give that address to a second computer. The fix is to find the IP address that is causing the problem and block it in your router so it no longer works. That will force the person misusing it to change their address. You might have to bump them a few times until they quit abusing the LAN and use the DHCP system to get their address." quoted from Stan )

 

Based on what he was saying they told him this AM I think this is what is occuring.

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I sort of get it. According to the park owner here he is getting the explanation from the local company that we are having a clash of duplicate ipaddress' on his wifi set up. I think he is trying but is not skilled at this and is skeptical of the explantion. He seems to think it is tied to someone here the park that is leaving thier computer/printer on line 24/7 that somehow is showing the same ipaddress. I know at least a couple or more are likely using verizion phone/hotspot or something through their dish or the like. It is not causing me a lot of issues but is slightly irritating. The park owner is conceintious about his service being available even though he uses it marginally himself.

 

I bet someone in the park is using a router as a wifi extender. ;) A quick way to fix the symptom is to reboot the park router. That will kick everyone off and eliminate conflicts for a while. If you want to go further, watch while people log back on to the router. When you start seeing conflicts, note the MAC address of the last one logging on before the problems started. Do this a few times to make sure you know who's causing the conflicts, then block that MAC from your network.

 

edited to add: oops, I see someone else has already given you very similar advice. Cheers, hope you get it fixed.

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AprilWhine has the most likely thing for this particular scenario. The other explanations are correct, but not likely in the park scenario if the park router is set up properly.

 

What is happening is someone has a CPE/wifi capture device that they are configuring themselves. And they are doing it wrong and stomping on an in-use address. LIkely they are configuring in the DHCP range. This is why I discourage people from setting up these devices themselves - much better to buy a WiFiRanger or Rouge Wave.

 

Reboot the park router and hope it does not show up again.....but it will if the person configures in the DHCP range. The proper thing to do is to let the CPE get assigned an address by the DHCP server in the park.

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I didn't find any simple instructions for finding a conflict in Windows, anybody have some steps he could follow without having to become a networking guru?

 

The nmap command doesn't appear to be available in Win 7, using "arp -a" in a command window will get you a list of IP addresses and the associated MAC addresses.

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I didn't find any simple instructions for finding a conflict in Windows, anybody have some steps he could follow without having to become a networking guru?

 

The nmap command doesn't appear to be available in Win 7, using "arp -a" in a command window will get you a list of IP addresses and the associated MAC addresses.

Years ago (5 which is several generations in equipment time) when a conflict poped up a warning window it would give you the IP address of the conflict. if you can catch that it may help. Usually a conflict did not cause any issues but our data packges were smaller and repeated several times before a machine would or could move in the real world. When talking about data for internet movies, facebook andwhat not ( things we think we can't live without. LOL!) no such safeties are required and would slow down communications to thr point of uselessness. Fortunately we kept records (excel spreadsheets) of all assigned IP addresses and MAC addresses. Everything was static over each of several LAN networks. There was always some engineers messing around and making changes and screwing things up. Usually a IP scanner would help (available at CNet) but they are viewed as spyware in big corporations. It was one of my jobs to keep things straight ... It was a never ending battle to keep those networks clean, organized and working. Good Luck.

Paul

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No service Sat. or most of today. If it is up to me and Walter to solve it we are in trouble. This is fairly new to this park. I have been here multiple months for multiple winters and this is the first time this has come up. As a separat issue, the local provider bought out the previous one and is not up to the standards of the previous one according to several local folks I know. I have one son in law in the area that is limited to this provider and agrees. They aren't really bad per se just obviously not as good as previous.

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Well there is one non-technical option that will likely make folks less than happy while you are doing it but will work.

 

Shut down the router to kick everyone off the net. Turn it back on and disable the WiFi while you do the rest of these steps.

 

Switch the local (NAT) LAN address, you will have an address something like 192.168.0.1 switch it up to different 192 range number, avoiding 192.168.0.1, 192.168.1.1, 192.168.10.1 and 192.168.100.1 which are commonly used default reset addresses that can lead to unneeded conflicts in the future. We will use 192.168.5.1 as an example from here on.

 

Set the DHCP range to the 100 to 150 range, 192.168.5.100 to 192.168.5.150 which will allow 50 users on your system. If you need more you can use numbers from .2 to .254 but try to not too far over your usual number of users.

 

Turn the WiFi back on and the users will be able to reconnect.

 

If it was an IP related problem you will have someone or ones that can't connect and see the internet. They likely have their computer or access device set to use a static IP address. Have them change their settings to use DHCP and you should have them back on-line.

 

If this happens again in the future you can easily go back in, change the local LAN address to another 192.x.x.1 number and boot the offender off again.

 

 

That is about as non-technical a fix as I can think of, if you can find or download your router's manual it should talk you through making all these changes.

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Barring the use of a network analyzer, Stanley's method of "fixing" this is probably the best choice. A complete change of the subnet. The use of the 192.168.1.x subnet is often problematic because so many routers default to it. I routinely change them.

 

Remember to set the subnet mask to 255.255.255.0 (or /26 if that's the way your router is configured) or you will get some serious issues. Set the default gateway to the .1 address.

 

I would choose a weird subnet address; something like 192.168.126.0/255.255.255.0. Following Stanley's advice will probably fix it, however.

 

Do not mess with the WAN address!!!

 

WDR

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I wish my sieve of a brain could remember some stuff better. Anyway, Walter had a guy from the local provider out here earlier today and I think we got a new router. Also we had a wet phone line down near the entrance but it didn't start raining until late last night (and it rained a ton) so I don't think that was a factor most of the weekend. I do know from talking to Walter that we are most likely on the outside edge as far as what is available from the parks system and the local provider up the line. In one way that makes me think we have been fairly fortunate here about park people not abusing it on a regular basis. I do know that at least 3 people in the near area must be using hotspots or phones for access.

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