Ubuntu 16.04 server - static ip address and new surprise DHCP address ? Why ?

Discussion in 'Networking' started by DrStein99, May 14, 2018.

  1. DrStein99

    DrStein99 Member

    Feb 3, 2018
    Likes Received:
    I have 2 ip addresses on my interface:

    $ ifconfig

    eno1      Link encap:Ethernet  HWaddr d4:ae:52:70:0f:b9
              inet addr:  Bcast:  Mask:
              inet6 addr: fe80::d6ae:52ff:fe70:fb9/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:5656 errors:0 dropped:0 overruns:0 frame:0
              TX packets:3712 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000
              RX bytes:4018398 (4.0 MB)  TX bytes:331856 (331.8 KB)
    Shows "" (which is the PHANTOM one I from DHCP I do not know how / why).

    $ ip addr
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host
           valid_lft forever preferred_lft forever
    2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
        link/ether d4:ae:52:70:0f:b9 brd ff:ff:ff:ff:ff:ff
        inet brd scope global eno1
           valid_lft forever preferred_lft forever
        inet brd scope global secondary eno1
           valid_lft forever preferred_lft forever
        inet6 fe80::d6ae:52ff:fe70:fb9/64 scope link
           valid_lft forever preferred_lft forever
    As you can see the is "scope global eno1" and "" is "scope global secondary eno1". So where the heck is it getting this FIRST one ( from ?!?!?

    This is all that I have configured (intentionally)

    # This file describes the network interfaces available on your system
    # and how to activate them. For more information, see interfaces(5).
    source /etc/network/interfaces.d/*
    # The loopback network interface
    auto lo
    iface lo inet loopback
    # The primary network interface
    auto eno1
    # iface eno1 inet manual
    iface eno1 inet static
    Can someone please help me understand where the phantom dhcp address is coming from if it is not listed here on my etc/network/interfaces ?!?!
  2. dandanio

    dandanio Member

    Oct 10, 2017
    Likes Received:
    Do you have anything in
    source /etc/network/interfaces.d/* ?

    Is there a second DHCP server on the network?

    First glimpse - it looks like you get 2 IPs from the DHCP server (or 2 servers?). I'd like to see the logs on the dhcp host, arp table, dmesg and /var/log/syslog.

    I have not seen such behavior.

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