Why one interface has two addresses [SOLVED]

[wes33]

I notice that my ethernet interface connected to ISP’s router has two ip addresses, like this:

3: enp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 30:5a:3a:47:07:72 brd ff:ff:ff:ff:ff:ff
inet 192.168.2.13/24 brd 192.168.2.255 scope global dynamic noprefixroute enp6s0
valid_lft 242739sec preferred_lft 242739sec
inet 192.168.2.18/24 brd 192.168.2.255 scope global secondary dynamic noprefixroute enp6s0
valid_lft 242748sec preferred_lft 210348sec

Only the 192.168.2.18 works for remote connections via port-forwarding. Why are there two IP addresses?

[xabbu]

Two dhcp clients running? Check the usually suspects and make sure you are only using one.

[linux-aarhus]

arp poisoning - reboot your network - that is power everything down - and power up in sequence starting with your router.

[wes33]

though not as exciting, I think xabbu is on the right track. Here from my logs:

Oct 30 08:58:17 gandalf NetworkManager[519]: [1604062697.6145] dhcp4 (enp6s0): option ip_address => ‘192.168.2.13’

and

Oct 30 08:58:24 gandalf dhcpcd[937]: enp6s0: leased 192.168.2.18 for 259200 seconds

If I disable networkmanager service then only .18 is assigned …

Do you know how to disable networkmanager’s dhcp client?

[linux-aarhus]

if you use network manager - disable dhcpcd

systemctl disable --now dhcpcd

If you use dhcpcd - disable network manager

systemctl disable --now NetworkManager

[wes33]

Actually, if I disable both NetworkManager and dhcpcd I still get the 192.168.0.18 address at boot, the log shows:

Oct 30 09:13:49 gandalf dhcpcd[934]: enp6s0: leased 192.168.2.18 for 259200 seconds

What’s calling /usr/bin/dhcpcd I wonder ?

[xabbu]

Check

systemctl status dhcpcd

[wes33]

the output of systemctl status dhcpcd:

dhcpcd.service - dhcpcd on all interfaces
Loaded: loaded (/usr/lib/systemd/system/dhcpcd.service; disabled; vendor preset: disabled)
Active: inactive (dead)

the service dhcpcd is not running but I guess something is calling the program dhcpcd at boot, if that makes any sense

[xabbu]

Is dhcpd still running?

Check

systemctl status

If it is running, it should show which service started the binary.

---

You can also check the journal with -o verbose

For exmaple

journalctl -o verbose --since "09:13:40" --until "09:13:50" 

[wes33]

You guys are great
The verbose logs show netctl calling dhcpcd according to the interface’s profile. So I don’t need networkmanager or dhcpcd service, which I like. All good, thanks. I’ll mark solved.

[cscs]

(Mod Note - while others assisted in finding the logs and such … your post best describes the issue, its cause, and possible response. So I have marked that as the solution for now.)