How to fully reset network settings on 18.04?

networking 18.04 network-manager 18.10

24,160

Ubuntu 18.04 no longer uses ifupdown(/etc/network/interfaces). That is where you are going wrong

They switched to netplan, huge pain. See more info here

24,160

João Pimentel Ferreira

Updated on September 18, 2022

Comments

João Pimentel Ferreira over 1 year

I upgraded to Ubuntu 18.04 and suddenly I don't have internet on command line, wired nor wireless, some domains seem not to resolve, though ping 8.8.8.8 does work, but service networking status is outputting error. I saw many tweaks here on askubuntu regarding the issue, with ifconfig or /etc/network/interface but none fully works. sudo service network-manager restart does not work either.

My network is basically a mess. Is there a way to fully reset network settings to a functional one? How is it possible that Ubuntu is releasing a main distro with such a bug, since this is a hot topic around?

Edit:

output of ifconfig

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        ether 00:8c:fa:8a:7c:ba  txqueuelen 1000  (Ethernet)
        RX packets 12829  bytes 5924414 (5.9 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 8755  bytes 1396496 (1.3 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 40521  bytes 4309970 (4.3 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 40521  bytes 4309970 (4.3 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.3  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::5e82:7f12:37f8:854f  prefixlen 64  scopeid 0x20<link>
        ether 34:de:1a:7f:93:1a  txqueuelen 1000  (Ethernet)
        RX packets 27441  bytes 22237443 (22.2 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 18332  bytes 5607005 (5.6 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

output of ip addr && cat /etc/resolv.conf && sudo lshw -C Network

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 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:8c:fa:8a:7c:ba brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 34:de:1a:7f:93:1a brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.3/24 brd 192.168.1.255 scope global dynamic noprefixroute wlan0
       valid_lft 84519sec preferred_lft 84519sec
    inet6 fe80::5e82:7f12:37f8:854f/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.

nameserver 8.8.8.8
nameserver 127.0.0.53
options edns0
  *-network                 
       description: Ethernet interface
       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:07:00.0
       logical name: eth0
       version: 0c
       serial: 00:8c:fa:8a:7c:ba
       size: 1Gbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl8168g-2_0.0.1 02/06/13 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
       resources: irq:16 ioport:3000(size=256) memory:c1700000-c1700fff memory:c1400000-c1403fff
  *-network
       description: Wireless interface
       product: Wireless 3160
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:08:00.0
       logical name: wlan0
       version: cb
       serial: 34:de:1a:7f:93:1a
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=4.15.0-45-generic firmware=17.948900127.0 ip=192.168.1.3 latency=0 link=yes multicast=yes wireless=IEEE 802.11
       resources: irq:33 memory:c1600000-c1601fff

cat /etc/apt/sources.list:

# deb cdrom:[Ubuntu 15.10 _Wily Werewolf_ - Release amd64 (20151021)]/ wily main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

## Major bug fix updates produced after the final release of the
## distribution.

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.


## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
deb http://archive.ubuntu.com/ubuntu bionic main universe restricted multiverse
## respective vendors as a service to Ubuntu users.
deb http://security.ubuntu.com/ubuntu/ bionic-security universe multiverse restricted main
deb http://archive.ubuntu.com/ubuntu bionic-updates universe multiverse restricted main
deb http://archive.ubuntu.com/ubuntu bionic-backports universe multiverse restricted main
deb http://archive.canonical.com/ubuntu bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner
deb [arch=amd64,i386] https://deb.opera.com/opera-stable/ stable non-free
# deb-src [arch=amd64,i386] https://deb.opera.com/opera-stable/ stable non-free

Omari Celestine about 5 years

When you run the command ifconfig, do you see the adapters there?
AlexOnLinux about 5 years

what's the output of ip addr && cat /etc/resolv.conf && sudo lshw -C Network?
João Pimentel Ferreira about 5 years

@OmariCelestine thank you so much for replying. I edited the question according to your instruction. Could you kindly recheck?
João Pimentel Ferreira about 5 years

@AlexOnLinux thank you so much for replying. I edited the question according to your instruction. Could you kindly recheck? Thanks
AlexOnLinux about 5 years

colbycdev mentiones a good point netplan. i do not have ubuntu 18 installed, so i can only refer to the manual either. Perhaps you have some old configurations in /etc/network/interfaces that now are in conflict with the new system, i dont know. What suprises me is the fact that you recieve an ip from your AP. Your resolv.conf looks a littel strange to me, i would have expected your gateway / router ip in there - a line with the following content: nameserver 192.168.1.1 and another line with nameserver 127.0.1.1. you say: "no internet via command line" - via browser it's working?
João Pimentel Ferreira about 5 years

@AlexOnLinux yes, odd, via browser is working but for example apt update not working. How do I amend my nameservers then?
João Pimentel Ferreira about 5 years

@AlexOnLinux cat /etc/network/interfaces just output # interfaces(5) file used by ifup(8) and ifdown(8) \ auto eth0 \ iface eth0 inet dhcp
AlexOnLinux about 5 years

as nameserver you are actl using 8.8.8.8. thats google dns. in general that should work either. i dont understand why browsing works while terminal shouldn't. to me that makes no sense. are you sure your apt is pointing to the correct links for your upgraded ubuntu version? check your /etc/apt/sources.list but i have to admit i am out of ideas. askubuntu.com/a/1036749/669014
João Pimentel Ferreira about 5 years

@AlexOnLinux when I go to software & update GUI dialog and then click select best server none server is presented.
João Pimentel Ferreira about 5 years

@AlexOnLinux I edited the question and added the output of sources.list
João Pimentel Ferreira about 5 years

I cannot access http://in.archive.ubuntu.com/ubuntu/ from my browser. Really strange!
AlexOnLinux about 5 years

Joao, i am really out of ideas. perhaps this is an IPv4 IPv6 problem. This would explain why sometimes connection works and sometimes it does not. Can you connect to this site ipv6-test.com does it show any errors regarding ipv4 or ipv6? You could test forcing ipv4 askubuntu.com/a/759540/669014 or disabling ipv6 askubuntu.com/a/484487/669014
João Pimentel Ferreira about 5 years

@AlexOnLinux http://ipv6-test.com/ doesn't event load. nba.com doesn't load either on browser. http://ubuntu.com/ doesn't load on the browser.
AlexOnLinux about 5 years

Let us continue this discussion in chat.
user535733 about 5 years

Voting to close - OP left an answer admitting he had a misconfigured router. Not an Ubuntu issue at all.
João Pimentel Ferreira about 5 years

@user535733 I also voted to close it as I agree with you

João Pimentel Ferreira about 5 years

I read the article, but how can I go from there?
machineaddict over 4 years

also, the /etc/network/interfaces file exists and is very misleading. it doesn't matter what's inside of it.