It implies much more than just your address.
It all depends on how they got your IP address and whether itâs really yours at all.
At least one scenario represents a serious security risk, but there are also situations in which itâs not really an issue under your control.
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My neighbor and my IP address
- The only way your neighbor can truly be using your IP address is if they have access to your local network.
- The most common scenario is that theyâve connected to your open wireless hotspot. Secure the hotspot by adding a wireless password.
- Itâs also possible that your IP address has changed, and was once theirs.
- Itâs very easy to misread IP address information, depending on your source.
- Malicious software on your machine could also be sending email appearing to be from your neighbor.
It implies theyâre on your network
If your neighbor is truly using your IP address, it implies they are connected to your network.
Thatâs a bad thing, unless you trust them and have explicitly allowed them to do so. Iâm guessing from your question thatâs not the case.
The most common reason is that you have an open wireless hotspot.
- You have a wireless router or access point.
- The wireless connection is not password protected.
- Your neighbor is in range and is using it.
Your neighbor could be completely unaware. It can happen accidentally if theyâre not paying attention to what theyâre connecting to. I would not assume malicious intent unless you have information that says otherwise.
The fix is very simple: password-protect the wireless connection. Configure the wireless access point to use WPA2 or 3, which requires a password to connect.
No one except those youâve authorized will be able to connect to your network.
As a bonus, your connections will be encrypted and no one will be able to âsniffâ them (as is possible at most free wireless hotspots).
Other explanations
There are a few other reasons your neighbor might appear to have sent email âfromâ your IP address.
You could have misread the email headers. Your IP address, as the destination when you download your email, may appear within it, in addition to the IP and email address the mail was sent from.
You and your neighbor could have IP addresses assigned by the same ISP. This has two interesting ramifications:
- Your IP address could be very similar to that of your neighbor. Even a single-digit difference means itâs a different IP address. Read the IP addresses carefully.
- IP addresses can change; your IP address today could easily have been your neighborâs IP address yesterday, when they were sending email.
The email might not be from your neighbor at all. Your machine could be infected with a spam-sending virus or bot, and it could be spoofing the âFromâ address so as to appear that it was sent by your neighbor.
Changing your IP address
Can you change your IP address? Well, it depends.
First, if youâve been assigned a static (unchanging) IP address, youâll need to contact your ISP and coordinate changing it with them.
If you have a more common dynamic IP address (if you donât know, then it likely is), you can try to change the address by unplugging your internet-connected modem and/or router, waiting awhile, and plugging it back in again. This causes it to âaskâ for a new IP address.
The problem here is that thereâs no way to force the newly assigned address to be different than whatever you had before. Many ISPs try to give you the same IP address for âa whileâ, even when youâre not connected for a time, as it can be slightly more efficient for them.
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ââŠimportant to note that your neighbor could be completely unawareâŠâ.
Excellent point, Leo. You truly stand out in the advice sector. That little comment probably has 50% of your readers relaxing. Put down the AK47s and tomahawks, folks, most things done by newbies are unintentional.
Amazing how many folks immediately think the worse. I run into this most of the time. It is never their âfaultâ for not following protocol or just simple tried and proven good computing steps.
Goos advice, Leo. Kudos.
Awwwww, how did you know I was going to suggest putting a hatchet in the neighborâs computer? :-D
A question that came to me in the first place was âhow did the guy know his neighbor had used his IP address?â Itâs not exactly displayed by default in any email program (local or webmail) Iâve heard of. And since I have DHCP, I generally donât know what my IP address is at any given time; I usually go to http://www.whatismyipaddress.com if I even need to know. (Hey, Leo! Another tip! âHow to find out what your IP address is!â)
20-Jul-2009
Weeble â itâs been done: http://ask-leo.com/whats_my_ip_address.html
Itâs not so good that in the US, routers are often configured with unsecured wireless access and itâs up to the user to create an access key. My Fritzbox router in Germany is preconfigured with a unique key printed on the router. The number can be read by anyone who has access to the router, but until I know someone has compromised this key (detached the router and copied the number) Iâll stick with it as my kids are often changing computers and in spite of the small risk, the convenience is worth it at the moment.
It still amazes me (though to a lesser degree) how many people simply plug in a wireless router and go. At the moment, my laptop sees three SSIDs of âlinksysâ, all unsecured. Out of curiosity, I have on occasion, connected to one of them, brought 192.168.1.1 up in my browser, and logged into the administrator control panel using the out-of-the-box login and password. Good thing my morals prevent me from doing anything malicious.
Another Point to Remember â Make sure you keep your Network Security password ID written down in a safe place in the even you forget it. Also, when setting up your encryption â make sure you do your homework first- as some older wireless cards may not be compitable with some of the newer encryption. If you like online games â check this out: [link removed]
If the neighbor is in fact sharing a wireless connection, and that connection is like my Linksys Wireless Router, the local router will get an IP address from the ISP and then assign a DHCP address to each unit on the local network. Commonly this is in the default range of 192.168.1.xxx. The 192.168.1.xxx range of IP addresses is ânot routableâ and will not be passed across the router to the outside world.
To the outside world (on the other side of the router from the local network) there is a single IP address assigned by the ISP to the router port directly connected to it. The router determines which local IP address is involved in the transaction and passes the traffic through to the appropriate hidden and non-routable local address. That is part of what routers do.
So from the outside world perspective, every unit served by the local router appears to be the same IP address that was provided by the ISP.
The result of all this is that anyone who sends an e-mail from the local network will appear to have sent from the same ISP assigned IP address that is assigned to the port on âworldâ side of the router and to be using the ISP assigned address. The 192.168.1.xxx IP addresses are not disclosed across the router to the outside world.
This is a probable answer as to why the addresses are the same.
The other comments about the neighborâs use of the same wireless network by design or ignorance are germane. Appropriate wireless connection security is the answer.
Another good tip to stop a neighbor using your IP address, is to set up an access list on your router, that is of course assuming that your router supports this.
An access list will allow you to limit the devices that can access your network by specifying their MAC addresses.
22-Jul-2009
I agree with Gary, I found the easiest way was to specifiy the MAC addresses in the router set-up. Most modern (last 5 years) routers seem to support this.
You still did not answer the question-how he knew his neighbor was using his IP address. I am curious to know that.
23-Jul-2009
All of the comments are great and true.
Another way to secure your wireless is to Disable your SSID broadcast.
âŠ.Robert
23-Jul-2009
You may be surprised to know that in my country many ISP (They call them ISP) provide IP address to customer directly from there switch/hub with more then /29 subnet! Also many customer in same subnet and there is no protection at all! yes this is true. If asker is in this scenario, I would suggest him/her to change that âunsecuredâ ISP. I worked for my Governmentâs Cyber Security Department for while and found it is very common practice among ISPâs in my country.
Bauaniâs Tech Blog
I filled a form with my phone number and house address.when connecting wireless.now anyone can look up my e-mail address and get my name,phone number and physical address.Is there anyway for me to erase,hide or change the information ?
25-Jul-2009
if you know how many computers will connect to your network, can you restrict this number? Would such a restriction only be applicable, though, assuming all of your computers(full capacity of allowed connections) were filled and active at all times the network is active?
Also, a question about networks. I am connecting to the Internet using a wireless router which is connected to a cable modem. I have disabled file-sharing on my computers. Is this strictly a Wireless Internet Access point then? How can I tell if the computers which use this wireless access to the Internet are exposed or able to be explored by any other computers using this connection?
My neighbour has an open system, when I (out of interest of course)I had a look at her router settings, I found my computer name under LAN clients, does that mean she would be able to access my computer?
Bob.