I leaked my IPv6 address and MAC address, should I be worried

@f33dm3bits I have a raspberry pi, and the micro sd card with the OS on it shows one IPv6 address on it. But when I switch to a different micro sd card with another OS on it, it's showing a completely different IPv6 address. I'm not resetting the router, I'm just switching from one OS to another. Now I'm confused. Shouldn't all devices on the network have the same public IP address?
 


We just learned that public IP is changing from time to time, the first half should stay the same though.
It could be the IP changed because of IP privacy exactly when you rebooted, it depends on your interval but I have no clue how to check or change it.
 
ip a && ip r shows your IPv6 addresses. I don't know if there's a command that shows only the IPv6 addresses, I'm sure there is. But this command has that info in there.
 
But when I switch to a different micro sd card with another OS on it, it's showing a completely different IPv6 address.
As I said before the ipv6 a device get can be different. I'm not sure when that is but I would think each time it reconnects but the main thing is that ipv6 address a device can have is different at times out of privacy reasons.

it's showing a completely different IPv6 address. I'm not resetting the router, I'm just switching from one OS to another. Now I'm confused. Shouldn't all devices on the network have the same public IP address?
No that's how it was with ipv4, with ipv4 your lan gets a private range and your router gets a public ip and then your router use NAT so that the private ranges can connect to the internet. With ipv6 every device gets a it's own public ipv6 address and also a link local address as @CaffeineAddict mentioned so that they can talk locally to other devices on your local network. There is better and more technical term for the local network with ipv6 but I forgot the name for it.
 

f33dm3bits Can a network have both IPv6 and IPv4 addresses? I'm looking at my windows computer and it's showing a link-local IPv6 address, but the public address is showing IPv4 on command prompt.​

 
@Kristeen wrote:
I realized it contained my MAC address, my private IPv6 address and my public IPv6 address. And anything else that I haven't realized. Did I mess up? Do I need to be worried? What can someone do with that information? And if I should be worried, what should I do?

In investigating network connectivity it is very useful to look at output from some tools like ip. The user can anonymise details before pasting them into a forum. Below is some output from the ip command, and below it is the same command piped though another command that replaces all the mac address numbers with an x, disidentifying them:
Code:
[tom@min ~]$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute
       valid_lft forever preferred_lft forever
2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 5c:5b:60:39:67:48 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.5/24 brd 192.168.0.255 scope global dynamic enp3s0
       valid_lft 61531sec preferred_lft 61531sec
    inet 192.168.0.4/24 brd 192.168.0.255 scope global secondary enp3s0
       valid_lft forever preferred_lft forever
    inet6 2001:8003:cc3c:1f01:9e6b:ff:fe29:3748/64 scope global dynamic mngtmpaddr proto kernel_ra
       valid_lft 4619sec preferred_lft 4619sec
    inet6 fe80::9e6b:ff:fe29:3748/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
3: wlp0s20f3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether f3:47:66:89:34:4f brd ff:ff:ff:ff:ff:ff



[tom@min ~]$ ip a | sed -r 's/([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}/xx:xx:xx:xx:xx:xx/g'
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback xx:xx:xx:xx:xx:xx brd xx:xx:xx:xx:xx:xx
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute
       valid_lft forever preferred_lft forever
2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd xx:xx:xx:xx:xx:xx
    inet 192.168.0.5/24 brd 192.168.0.255 scope global dynamic enp3s0
     
  valid_lft 59792sec preferred_lft 59792sec
    inet 192.168.0.4/24 brd 192.168.0.255 scope global secondary enp3s0
       valid_lft forever preferred_lft forever
    inet6 2001:8003:cc3c:1f01:9e6b:ff:fe29:3748/64 scope global dynamic mngtmpaddr proto kernel_ra
       valid_lft 4585sec preferred_lft 4585sec
    inet6 fe80::9e6b:ff:fe29:3748/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever
3: wlp0s20f3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd xx:xx:xx:xx:xx:xx

The sed command, cumbersome as it looks, can be made into an alias which I leave for the reader to research if unclear.

To also delete the IP6 address, one can run the same command with the addition:
Code:
ip a | sed -r 's/([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}/xx:xx:xx:xx:xx:xx/g' | sed '/inet6/d'

The output of the ip command shows that the ethernet is UP, meaning it's ready online. The wifi here is DOWN, which means the interface is not operating, and other relevant details remain.
 

f33dm3bits Can a network have both IPv6 and IPv4 addresses? I'm looking at my windows computer and it's showing a link-local IPv6 address, but the public address is showing IPv4 on command prompt.​

Yes both ipv4 and ipv6 can be used as in the world is still in transition phase from ipv4 to ipv6 and not everything supports ipv6 yet. So both can be used, there are different methods of doing that but I don't know enough about those to properly explain how those work.
 
I'm looking at my windows computer and it's showing a link-local IPv6 address, but the public address is showing IPv4 on command prompt.
command prompt should show private IPv4 address, not sure which command you used, if it's ipconfig then it shows private IPv4 address meaning you're connected to IPv4.

Private address starts with either 192.168.*.* or 172.16-31.*.* or 10.*.*.*
 
@Kristeen wrote:


In investigating network connectivity it is very useful to look at output from some tools like ip. The user can anonymise details before pasting them into a forum.
So they probably weren't hackers trying to get me to post my info? How bad is it that I posted that info? They could have at least told me about sed, or warned me to anonymize my personal details.
 
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command prompt should show private IPv4 address, not sure which command you used, if it's ipconfig then it shows private IPv4 address meaning you're connected to IPv4.
I used ipconfig. On my windows computer it shows the private address as IPv6 and the public is IPv4. On my raspberry pi both the private and public are IPv6.
 
A Public IP address is an IP address that can be accessed directly over the internet and is assigned to your network router by your internet service provider (ISP). Your personal device also has a private IP that remains hidden when you connect to the internet through your router’s public IP.
Using a public IP address to connect to the internet is like using a P.O. box for your snail mail, rather than giving out your home address. It’s a little bit safer, but a lot more visible.

A Private IP address is the address your network router assigns to your device. Each device within the same network is assigned a unique private IP address (sometimes called a private network address) — this is how devices on the same internal network talk to each other.
Private IP addresses let devices connected to the same network communicate with one another without connecting to the entire internet. Private IP addresses are traceable, but only by other devices on your local network. Each device connected to your local network has a private IP address, and each device’s private IP address can be seen only by other devices within that network.

Hope this helps
 

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