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Thu Feb 25, 2021, 01:12 PM

Can you smart folks explain some things about IP addresses for me?

A while ago we were at our vacation house and Facebook or Outlook or something like that sent me a message that my account had been logged onto from an unknown (not sure that was the word) location, but that it was "the same IP address" as you are using now... or words to that effect.

Well, I thought, how do they know my IP address? That got me to thinking about more questions, especially because, now and then I'll assume extra identities at a site like Facebook, and I know they don't approve.

1 - Do places like FAcebook check for duplicate IP addresses?

2 - Can anyone tell if an IP address is from a public place, like a library?

3 - Is your IP address an attribute of your modem, or of your computer? (No smart phone in my world, so not an issue.)

4 - If you unplug your modem do you get a new IP address when you plug it back in?

5 - Any other thoughts that might be helpful to an ignoramus like myself?

tia
las

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Reply Can you smart folks explain some things about IP addresses for me? (Original post)
LAS14 Feb 2021 OP
sboatcar Feb 2021 #1
LAS14 Feb 2021 #4
LAS14 Feb 2021 #6
WHITT Feb 2021 #2
LAS14 Feb 2021 #3
CloudWatcher Feb 2021 #7
LAS14 Feb 2021 #8
LAS14 Feb 2021 #5
CloudWatcher Feb 2021 #9
LAS14 Feb 2021 #10

Response to LAS14 (Original post)

Thu Feb 25, 2021, 01:29 PM

1. I'll help you out here!

1 - Do places like FAcebook check for duplicate IP addresses?
Facebook monitors the IP address that you log in from to check for suspicious activity on your account. So if you suddenly log in from an IP that's located hundreds of thousands of miles away from where you usually log in, it will flag that as possibly suspicious.

2 - Can anyone tell if an IP address is from a public place, like a library?
If you are connecting to a site that logs such things, they could check for that if they wanted to. IP addresses are handed out by the ISP and they are traceable.

3 - Is your IP address an attribute of your modem, or of your computer? (No smart phone in my world, so not an issue.)
There are 2 types of IP addresses. Public and private. Your public IP address is the IP address of your modem, it is assigned by your ISP. The private IP address is for only inside your house and is assigned by your router. This is done for 2 reaons. 1-- To preserve IP addresses, the IPv4 addresses that most of the internet uses are limited to approximately 4 billion, so having a single IP address for your home, and then giving private IPs to the devices inside your home means that you're only using 1 IP. 2-- As a basic layer of security. Your home computer isn't really directly accessible to the internet via the public IP.

4 - If you unplug your modem do you get a new IP address when you plug it back in?
This depends. Every time you restart your modem, it goes to the ISP and asks for an IP address. Usually your IP address will be assigned for a certain amount of time, so every time you restart within that window you will get the same IP. The only way to guarantee a change would be to keep your modem unplugged for a long period of time (like 7 days or so)


5 - Any other thoughts that might be helpful to an ignoramus like myself?
You don't need to really worry about this too much, but feel free to ask more questions if you have them.

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Response to sboatcar (Reply #1)

Thu Feb 25, 2021, 03:02 PM

4. Thank you! nt

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Response to sboatcar (Reply #1)

Thu Feb 25, 2021, 03:32 PM

6. I thought of another question.

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Response to LAS14 (Original post)

Thu Feb 25, 2021, 02:04 PM

2. One More Important Thing You Should Know

IP addresses can easily be spoofed.


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Response to WHITT (Reply #2)

Thu Feb 25, 2021, 03:01 PM

3. What does that mean? Remember the "ignoramus" part of my OP. :-)

In particular, how much effort does it take for someone to find out the IP address of someone from their e-mail, or from their logging on to a web site?

tia
las

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Response to LAS14 (Reply #3)

Thu Feb 25, 2021, 03:33 PM

7. Return address

Every packet of information flowing on the internet has both a source and destination IP address. Think of it like the two addresses on an envelope in normal postal mail (the return address and the destination address for the mail).

And, just like when using postal mail, you can lie and put whatever you want in the source (senders) address.

This usually isn't much good, since an internet connection normally requires communications in both directions. But there are a few odd corners of the protocols where fibbing about the packet's origin can help the bad guys screw things up.

I.e. don't lose sleep over it


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Response to CloudWatcher (Reply #7)

Thu Feb 25, 2021, 03:34 PM

8. Thanks!! Snooze... :-)

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Response to LAS14 (Original post)

Thu Feb 25, 2021, 03:30 PM

5. I thought of another question.

From your responses, one could get the impression that detecting and using IP addresses is a higher level activity (network administrator, web administrator) than, say, a Facebook group administrator. Is that a fair assumption.

tia
las

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Response to LAS14 (Reply #5)

Thu Feb 25, 2021, 03:42 PM

9. detecting / using

Everyone that uses the internet is using IP addresses to communicate. It's no different than putting an address on an envelope to send postal mail, or getting an address from your post office to receive mail.

Many internet services don't bother recording the addresses of their customers. Some do to try and protect against account abuse (e.g. if your login name & password were stolen).

It's often considered semi-private data. E.g. if you have the IP address that someone on Facebook last used to login, then you could make progress in tracking them down in real life. There are services that will tell you the approximate geographical location of any IP address. These geo-location services are not terribly reliable, often getting you to the nearest large city instead of a real address. And they can be defeated by VPN (virtual private network) services. When using a VPN service, you appear to the rest of the internet as coming "from" the VPN and only the VPN and you know otherwise. I.e. they are used as a relay for your traffic and your real source IP address is (in theory) not shared.

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Response to CloudWatcher (Reply #9)

Thu Feb 25, 2021, 04:14 PM

10. Thank you!! nt

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