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user2315094
Asked: 2019-07-26 03:21:06 +0800 CST

Since this morning the network is unreachable Ubuntu 18:04

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This morning the networking in my Ubuntu 18.04 Server Edition is not working anymore :

marco@pc01:$ sudo lshw -class network
  *-network DISABLED
      description: Ethernet interface
      product: RTL8111/8168/8411 PCI Express 
        Gigabit Ethernet Controller
  *-network DISABLED
      description: Wireles interface
      product: AR9227 Wireless Network Adapter
  *-network:0
       description: Ethernet interface
       physical id: 2
       logical name : docker0
  *-network:1
       description: Ethernet interface
       physical id: 3

sudo nano /etc/nework/interfaces :

iface eth0 inet static
    address 192.168.1.7
    netmask 255.255.255.0
    network 192.168.1.1 
    broadcast 192.168.0.255
    post-up iptables-restore <  
      /etc/iptables.up.rules
    gateway 192.168.1.1
    dns-nameservers 192.168.0.5 8.8.8.8

marco@pc01:$ sudo service network-manager restart
 Failed to restart network-manager.service: Unit network-manager.service 
  not found

Even with sudo /etc/init.d/networking restart:

marco@pc01:$ sudo /etc/init.d/networking restart
[ok] Restarting networking (via systemctl):
 networking.service

marco@pc01:$ ping 192.168.1.4
 connect: Network is unreachable

What have I to do in order to make the network available again? Looking forward to your kind help Marco

1° Update:

marco@pc01:$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKOWN group
       default qlen 1000
   inet 27.0.0.1/8 scope host lo
     valid_lft forever preferred_lft forever
   inet6 ::1/128 scope host
     valid_lft forever preferred_lft forever
2: enp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group 
       default qlen 1000
     link/ether 78:24:af:43:ef:5c brd ff:ff:ff:ff:ff:ff
3: wlp5s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group 
       default qlen 1000
     link/ether c0:4a:00:09:0e:80 brd ff:ff:ff:ff:ff:ff  
4: b3-4f9fe03b1a66: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc 
       noqueue state DOWN group default
     link/ether 02:42:64:29:65:73 brd ff:ff:ff:ff:ff:ff
     inet 172.22.0.1/16 brd 172.22.255.255 scope global br-4f9fe03b1a66
       valid_lft forever preferred_lft forever
5: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue 
      state DOWN group default
    link/Ether 02:42:01:ea:90:66 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scoper global docker0
      valid_lft forever preferred_lft forever

2°Udate:

A)

marco@pc01:$ ifconfig eth0 up eth0: ERROR while getting interface flags: 
  eth0: ERROR while getting interface flgs: No such device
  eth0: Host name lookup failure

marco@pc01:$ ifconfig
br-4f9feo3b1a66: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
    inet 192.22.0.1 netmask 255.255.0.0 broadcast 172.22.255.255
    ether 02:42:4d:c4:bd:62 txqueuelen 0 (Ethernet) 
    RX packets 0 bytes 0 (0.0B)
    RX errors 0 dropped 0 overruns 0 frame 0
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

docker0: flags=4099<,UP,BROADCAST,MULTICAST> mtue 1500
    inet 172.17.0.1 netmask 255.255.0.0 broadcast 172.17.255.255
    ether 02:42:24:b9:3b:59 txqueuelen 0 (Ethernet)
    RX packets 0 bytes 0 (0.0 B)
    RX errors 0 dropped 0 overruns 0 frame 0
    TX packets 0 bytes 0 (0.0 B)
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

l0: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
    inet 127.0.0.1 netmask 255.0.0.0
    inet6 ::1 prefoxlen 128 scopeid 0x10<host>
    loop txqueuelen 1000 (Local Loopback)
    RX packets 258 bytes 32343 (32.3 KB) 
    RX errors 0 dropped 0 overruns 0 frame 0
    TX packets 258 bytes 32343 (32.3 KB)  
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

B)

/etc/network/interfaces :

  auto lo
  iface lo inet loopback

3° Update:

I modified the /etc/network/interfaces file as follows:

iface enp3s0 inet static
    address 192.168.1.7
    netmask 255.255.255.0
    network 192.168.1.1 
    broadcast 192.168.0.255
    post-up iptables-restore <  
      /etc/iptables.up.rules
    gateway 192.168.1.1
    dns-nameservers 192.168.0.5 8.8.8.8

But still no network.

4° Update:

  marco@pc01:$ uname -r
  4.15.0-55-generic

  marco@pc01:$ ls -al /etc/netplan
  total 20
  drwxr-xr-x 2 root root 4096 Jul 25 18:37
  drwxr-xr-x 128 root root 12288 Jul 25 12:51
  -rw-r--r-- 1 root root 616 Jul 25 18:37 30-cloun-init.yaml

   etc/netplan/50-cloud-init.yaml    :

     network:
         renderer: NetworkManager/ networkd
         ethernets:
           enp3s0:
               addresses: [192.168.1.7/24]
               gateway4: 192.168.1.1
               nameservers:
                   addresses: [8.8.8.8,8.8.4.4]
               dhcp4: no
         version: 2

 marco@pc01:$ sudo netplan apply
 sudo: netplan: command not found

For sudo llshw -c network : see above

5° Update : result of dpkg -l netplan 

marco@pc01:$ dpkg -l *netplan*
Desired=Unknown/Install/Remove/Purge/Hold
  Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-
       pend
    Err?=(none)/Reinst-required (Status,Err: uppercase=bad)

    Name              Version       Architecture  Description
    in netplan.io      <none>          amd64      (no description 
                                                   available)

6° Update : sudo lshw -c network

marco@pc01:$ sudo lshw -c network
  *-network DISABLED
      description : Ethernet interface
      product: RTL811178168/8411 PCI Express Gigabit Ethernet Controller
      vendor: Realtek Semiconductor CO., Ltd.
      physical id: 0
      bus info: pci@000:03:00.0
      logical name: enp3s0
      version: 11
      serial: 78:24:af:43:ef:5c
      size: 100 Mbit/s
      capacity: 1Gbit/s
      width: 64 bits
      clock: 33 Mhz
      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: autonegotiaion=on broadcast=yes driver=r8169 
                     driverversion=2.3LK-NAPI duplex=full latency=0 
                     link=no multcast=yes port=MII speed=100Mbit/s 
      resources: irq:18 ioport:d000(size=256) memory:f7200000-f7200fff 
                 memory:f2100000-f2103fff
   *-network DISABLED
      description: Wireless interface
      product: AR9227 Wireless NEtwork Adapter
      vendor: Qualcomm Atheros
      physical id: 0
      bus info: pci@0000:05:00.0
      logical name: wlp5s0
      version: 01
      serial: c0:4a:00:09:0e:80
      width: 32 bits
      clock: 66MHz
      capabilities: pm bus_master cap_list ethernet physical wireless
      configuration: broadcast=yes driver=ath9k driverversion=3.15.0-55-
                     generic firmware=N/A latency=168 link=no 
                     multicast=yes wireless=IEEE 802.11
      resources: irq:19 memory:f7100000-f10ffff
   *-network:0
      description: Ethernet interface
      physical id: 2
      logical name: docker0
      serial: 02:42:62:12:98:6e
      capabilities: ethernet physical
      configuration: broadcast=yes driver=bridge driverversion=2.3 
                     firmware=N/A ip=172.17.0.1 link=no multicast=yes
   *-network:1
       description: Ethernet interface
       physical id:3
       logical name: br-4f9fe03b1a66
       serial: 01:42:fc:9e:92:1c
       capabilities: ethernet physical
       consiguration: broadcast=yes driver=bridge driverversion=2.3 
                      firmware=N/A ip=172.22.0.1 link=no multicast=yes

7° update:

Two disks: 
  1° disk: 
    /dev/sda1 1M BIOS boot 
    /dev/sda2 1G Linux filesystem /dev/sda3 232G Linux filesystem 
     with sudo fsck -f : everything ok ;
  2° disk: 
    /dev/sdb1 1M BIOS boot 
    /dev/sdb2 232G Linux filesystem

    sudo fsck -f /dev/sdb1
    fsck from util-linux 2.31.1
    e2fsck 1.44.1 (24-Mar-2018)
    ext2fs_open2: Bad magic number in super-block
    fsck.ext2: Supeblock invalid, trying backup blocks...
    fsck.ext2: Bad magic number in super-block whule trying to open 
               /dev/sdb1
      The superblock could not be read or does not describe a valid 
ext2/ext3/ext4 filesystem (and not swap or ufs or something else), then 
the superblock is corrupt, and you might try running e2fsck with an
alternate superblock:
  e2fsck -b 8193 <device>
or
  e2fsck -b 32768 <device>

Can I install netplan even if /dev/sdb1 might contain a corrupted superblock?

8°update:

ubuntu@ubuntu:$ sudo fsck -f /dev/sda2
fsck fromutil-linux 2.31.1
e2fsck 1.44.1 (24-Mar-2018)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/sda2: 309/65536 files (2.9% non-contiguous), 48744/262144 blocks

ubuntu@ubuntu:$ sudo fsck -f /dev/sdb2
fsck from util-linux 2.31.1

9° update: After modifying /etc/netplan/01-network-manager-all.yaml :

ubuntu@ubuntu:/etc/netplan$ sudo netplan --debug generate
DEBUG:command generate: running ['/lib/netplan/generate']
** (generate:4715): DEBUG: 15:57:43.284: Processing input file 
                    /etc/netplan/01-network-manager-all.yaml..
** (generate:4715): DEBUG: 15:57:43.285: starting new processing pass
                    to 1
** (generate:4715): DEBUG: 15:57:43.285: Configuration is valid
** (generate:4715): DEBUG: 15:57:43.285: Generating output files..
** (generate:4715): DEBUG: 15:57:43.285: NetworkManager: definition 
                    enp3s0 is not for us (backend 1)
networking network-monitoring 18.04

2 Answers

  1. Best Answer

    Your /etc/network/interfaces file should be:

    auto lo
iface lo inet loopback

    Your /etc/netplan/*.yaml file should be:

    network:
  version: 2
  renderer: networkd
  ethernets:
    enp3s0:
      addresses: [192.168.1.7/24]
      gateway4: 192.168.1.1
      nameservers:
        addresses: [8.8.8.8,8.8.4.4]

    and then you should execute:

    sudo netplan generate # generate config files

    sudo netplan apply # apply config

    reboot # reboot computer

    Update #1:

    Something is really strange with your computer...

    • the sudo lshw -C network command isn't giving a complete answer

    • unless it's a manual typo(s), the /etc/netplan directory and file contents are weird

    • netplan doesn't seem to be installed

    You'd better check your file system before we reinstall netplan...

    • boot to a Ubuntu Live DVD/USB
    • open a terminal window by pressing Ctrl+Alt+T
    • type sudo fdisk -l
    • identify the /dev/sdXX device name for your "Linux Filesystem"
    • type sudo fsck -f /dev/sdXX, replacing sdXX with the number you found earlier
    • repeat the fsck command if there were errors
    • type reboot

    Now edit your .yaml file and proceed with my original answer.

    Update #2:

    Rather than trying to patch together a botched server, I'd recommend just reinstalling the server at this point.

    • 5

  2. Sounds similar to another post regarding a sudden unexpected network failure after everything was working fine for a long time.

    Too often, the system updates automatically and the new updates are "allergic" to your existing chipsets (just made up the word "allergic" for bugs).

    You may want to do the following to find your chipset

    • lspci | grep Ethernet

    Then you may have to resort to a USB drive and SneakerNet to search for the latest driver for your chipset using another computer or mobile device. I also have a USB ethernet dongle that often saves me from SneakerNet in such situations by getting me back online so I can work and also download drivers and utilities needed to get the onboard ethernet chipset working again.

    Hope it helps and good luck.

    • 0