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Setting up a KVM host on Ubuntu 18.04 with bridged networking

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Since the launch of Ubuntu server 18.04, I’ve had a few people ask me how to setup bridged networking since the changeover to netplan for networking. The setup’s actually quite straight forwards once you know how. Start out by installing KVM and associated packages (I’m assuming you’re on a fresh Ubuntu 18.04 box):

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sudo apt install bridge-utils qemu-kvm libvirt-bin

You should now be able to access virsh, to test it just run the command to list the virtual machines on the host (this will of course output an empty list. We just want to make sure the command hasn’t failed before going further):

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virsh list --all

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<h2> Id    Name                           State</h2>

Now edit the netplan file for the networking configuration of the host system:

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sudo nano /etc/netplan/50-cloud-init.yaml

The configuration should be edited to look similar to this:

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network:
    ethernets:
        eno1:
            addresses: []
            dhcp4: true
            optional: true
    version: 2
    bridges:
        br0:
            interfaces: [eno1]
            dhcp4: true
            parameters:
                stp: false
                forward-delay: 0

We’re basically defining a single ethernet port (eno1) and assigning it to a bride. Note that you can check your ethernet port name using the ‘ip address’ command on the command line and it will return your network adapters and IP addresses. It should be resonably obvious which one is your ethernet adapter from the list!

It’s worth noting that in this setup, we’re allowing DHCP to allocate addresses to the machine. If this isn’t what you want, take a look at the netplan examples here: https://netplan.io/examples

You can apply these change using:

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sudo netplan apply

And check it’s working:

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ip address

or

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networkctl list

If you’ve gotten this far without a network issue, you should be able to create machines using your favorite tool. I use Virtual Machine Manager (https://virt-manager.org/) which provides a reasonable user interface as well as remote management via SSH.

Setting up a Bond and Bridge in Netplan on Ubuntu 18.04

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For some of my Ubuntu 18.04 servers, I need to run KVM virtual machines which require a bridge to the network so the machines get public LAN IP addresses and aren’t hidden behind NAT. With the server configuration for both my co-location and work server room the network interfaces are all bonded for fail-over. This means I need a bond to have a bridge ontop of it for the virtual machines to get public IP addresses, while still allowing for failover of the network connection in the event of a network failure.

There are some good examples of setting up netplan here: https://netplan.io/examples

They have a bridge example:

Netplan bridge example
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network:
  version: 2
  renderer: networkd
  bridges:
    br0:
      dhcp4: yes
      interfaces:
        - enp3s0

And a bond example:

Netplan bond example
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network:
  version: 2
  renderer: networkd
  bonds:
    bond0:
      dhcp4: yes
      interfaces:
        - enp3s0
        - enp4s0
      parameters:
        mode: active-backup
        primary: enp3s0

But there’s not a clear indication of how to amalgamate the two. Here’s what I’ve ended up with in ‘/etc/netplan/50-cloud-init.yaml’:

Netplan bridge and bond
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network:
    bridges:
        br0:
            addresses:
            - 192.168.10.30
            dhcp4: false
            gateway4: 192.168.10.1
            nameservers:
                addresses:
                - 192.168.10.1
                - 192.168.10.2
                search: []
            interfaces:
                - bond0
    bonds:
        bond0:
            interfaces:
            - eno1
            - eno2
            parameters:
                mode: active-backup
    ethernets:
        eno1:
            addresses: []
            dhcp4: false
            dhcp6: false
        eno2:
            addresses: []
            dhcp4: false
            dhcp6: false

Note that I’ve obviously defined static IP addresses, but this isn’t a requirement. Just set ‘dhcp4: true’ and remove the ‘address’, ‘gateway’ and ‘nameserver’ sections if you’re using DHCP.

Once the file’s got that setup in it, it’s possible to run ‘sudo netplan apply’ and you should be able to run ‘networkctl list’ to check the bridge and bond are setup.

Fail2ban does not enable some rules

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While setting up a webserver, I noticed that

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fail2ban-client status

 did not list all of the rules that I’d configured in

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jail.d

. Althought configuration files were added to the directory, the status wasn’t showing them listed, so it hadn’t activated the jails. Running

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service fail2ban restart

 didn’t add them either.

After spending some time researching, some people suggest changing the backend used in fail2ban from auto to polling in jail.conf. Since you shouldn’t edit jail.conf on a debian based system, I tried creating a new file 

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nano /etc/fail2ban/jail.local

 and adding the line

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backend = polling

. This actually prevented the fail2ban service from starting for me. The errors in

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systemctl status fail2ban.service

didn’t show anything useful as to the cause of the error. In the end I reverted this change.

running

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fail2ban-client reload

 did present error messages detailing which rule couldn’t be activated:

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ERROR No file(s) found for glob /var/log/apache2/*.log
ERROR Failed during configuration: Have not found any log file for apache-xmlrpc jail

This then meant I was able to investigate the

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jail.d

 config file with the rule indicated as causing the problem and correct the log file path.

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fail2ban-client status

 then shows the correct jails running.

mount disk image created with dd using ubuntu

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If you’ve cloned a whole drive using dd and you need to access one of the partitions on it here are some steps to follow in order to gain access:

Find the partition start sectors using fdisk -b512 -l. Note that you’re explicitly setting the sector size to 512 bytes and you’ll need to change your command to match your own image file.

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fdisk -b512 -l backup_sata.img

You should get output similar to this (note I’ve truncated it to only show the appropriate output):

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Device         Boot     Start       End   Sectors   Size Id Type
backup_sata.img1 *         2048    206847    204800   100M  7 HPFS/NTFS/exFAT
backup_sata.img2         206848 237185023 236978176   113G  7 HPFS/NTFS/exFAT
backup_sata.img3      237185024 588070911 350885888 167.3G  f W95 Ext'd (LBA)
backup_sata.img4      588070912 625137663  37066752  17.7G 27 Hidden NTFS WinRE
backup_sata.img5      237187072 588070911 350883840 167.3G  7 HPFS/NTFS/exFAT

Normally sector are 512 bytes, so you can calculate the offset you need in the next command with:

start * 512 = offset

So if you want to mount backup_sata.img5 (partition 5 of the backup image) you’d run 237187072×512=121439780864:

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mount -o ro,loop,offset=121439780864 backup_sata.img /backup_sata

Remember to have created /backup_sata or whatever directory you’re mounting to first!

Linux Mint Docker “Error loading docker apparmor profile”

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I’ve recently been experimenting with Docker containers, but found there’s an error with installing it on Linux Mint:

Docker Error on Linux Mint
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2015/07/30 14:00:53 WARNING: Your kernel does not support cgroup swap limit.
Error loading docker apparmor profile: exec: "/sbin/apparmor_parser": stat /sbin/apparmor_parser: no such file or directory ()

It’s quite easy to solve, you just have to install app-armour:

Install apparmor
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sudo apt-get install apparmor

Then start the docker demon from the terminal to make sure it’s loading okay:

Start docker deamon
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sudo docker -d

You should see something similar to the following:

Docker starting
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2015/07/30 14:07:14 docker daemon: 1.0.1 990021a; execdriver: native; graphdriver:
[67068605] +job serveapi(unix:///var/run/docker.sock)
[67068605] +job initserver()
[67068605.initserver()] Creating server
2015/07/30 14:07:14 Listening for HTTP on unix (/var/run/docker.sock)
[67068605] +job init_networkdriver()
[67068605] -job init_networkdriver() = OK (0)
2015/07/30 14:07:14 WARNING: Your kernel does not support cgroup swap limit.
2015/07/30 14:07:14 Local (127.0.0.1) DNS resolver found in resolv.conf and containers can't use it. Using default external servers : [8.8.8.8 8.8.4.4]
Loading containers: : done.
[67068605.initserver()] Creating pidfile
[67068605.initserver()] Setting up signal traps
[67068605] -job initserver() = OK (0)
[67068605] +job acceptconnections()
[67068605] -job acceptconnections() = OK (0)

 

Once it loads this far, you can use ctrl + c to exit and start the service. If you have any further errors you’ll need to investigate further. Then start the service using:

Start docker service
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sudo service docker.io start