3 IP address from RPI3 eth + wlan +?

Question

I have a raspberry 3 connected by ethernet and wifi to my router. So I understand I should have 2 IP address referring to it.

But I wrote hostname -I and get 3 different IP addresses:
192.168.1.100, 192.168.1.33 and 192.168.1.35

Where does the third IP come from?

• if I disconnect the ethernet cable from the RPI and write again hostname -I I get:
  192.168.1.100 and 192.168.1.33

• this does not make sense with 'ifconfig' result:

  
  
  eth0      Link encap:Ethernet  HWaddr b8:27:eb:d6:xx:xx
            inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0
            inet6 addr: fe80::ba27:ebff:fed6:xxxx/64 Scope:Link
            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
            RX packets:23152 errors:0 dropped:6 overruns:0 frame:0
            TX packets:51977 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:1000
            RX bytes:12371346 (11.7 MiB)  TX bytes:58608891 (55.8 MiB)
  
  lo        Link encap:Local Loopback
            inet addr:127.0.0.1  Mask:255.0.0.0
            inet6 addr: ::1/128 Scope:Host
            UP LOOPBACK RUNNING  MTU:65536  Metric:1
            RX packets:416 errors:0 dropped:0 overruns:0 frame:0
            TX packets:416 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:1
            RX bytes:47205 (46.0 KiB)  TX bytes:47205 (46.0 KiB)
  
  wlan0     Link encap:Ethernet  HWaddr b8:27:eb:83:xx:xx
            inet addr:192.168.1.33  Bcast:192.168.1.255  Mask:255.255.255.0
            inet6 addr: fe80::8df4:f4d0:xxxx:115/64 Scope:Link
            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
            RX packets:28407 errors:0 dropped:23070 overruns:0 frame:0
            TX packets:4040 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:1000
            RX bytes:7492811 (7.1 MiB)  TX bytes:4725779 (4.5 MiB)
  

update: As Bugfinger pointed out the use of ip addr show shows which device the address is assigned to:

2: eth0:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether b8:27:eb:d6:fb:5a brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.100/24 brd 192.168.1.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet 192.168.1.35/24 brd 192.168.1.255 scope global secondary eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::ba27:ebff:fed6:fb5a/64 scope link
       valid_lft forever preferred_lft forever`
  

I have 2 different addresses to eth0:

scope global eth0 and scope global secondary eth0

Answer 1

Recent Raspbian versions (since Jessie) are using DHCP Client Daemon (DHCPCD) to configure network devices. So static IP addresses are to be configured in /etc/dhcpcd.conf. If you configured them to be static manually or via /etc/network/interfaces, you end up with one static and one dynamic IP address on the same device. As far as I read about it, it's not clear yet, if that's a bug in DHCPCD or an expected behaviour after mis-configuration.

Anyway, to change that, you have to do as follows.

To see if it is running, check the output of:

sudo service dhcpcd status

If it is not running, start it with:

sudo service dhcpcd start
sudo systemctl enable dhcpcd

If you did already changed /etc/network/interfaces, you need to revert those changes. The original contents of that file (in Jessie) is:

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

iface eth0 inet manual
allow-hotplug wlan0
iface wlan0 inet manual
   wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

allow-hotplug wlan1
iface wlan1 inet manual
   wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Now all interfaces should be configured through DHCP again. If you now want to set a static IP address for eth0, edit /etc/dhcpcd.conf and put in:

interface eth0
static ip_address=192.168.1.100/24
static routers=192.168.1.1 # or whatever your router is
static domain_name_servers=192.168.1.1 # same as router

After saving the file and sudo reboot, your Raspi should reboot with a static eth0 and a dynamic wlan0 and without the extra IP address hanging around.