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Creating a free5GC VM and Setting up Network

In this demo we will exercise:

  • Cloning an existing VM, and install free5GC on it
  • Setting up the networking for the free5GC VM

Tips

Refer to video Clone VM and Change IP.

1. Check up an existing VM for Cloning

Launch VirtualBox, and make sure the Ubuntu VM (ubuntu) we created before can boot up, then:

  • Log in into the VM using SSH from the host machine, and check if the VM has internet access
  • Make sure you have done sudo apt update and sudo apt upgrade (or you can do it again)
  • Shutdown the VM. You can:
  • use command sudo shutdown -P now, or
  • click the “Close Window” of the Ubuntu VM terminal and choose the middle option (better not force to turn off the machine power)
  • later if you just want to reboot, enter sudo shutdown -r now

2. Create a free5GC VM

First let’s clone a new VM:

  • Select an existing VM (ubuntu) and click the buttons on the right: / Snapshopts / Clone.
  • Name the new VM free5gc.
  • The MAC address rule: Create new MAC addresses for all network cards.
  • Choose the Link cloning option (or you can also choose to complete clone the VM if you like).

After the new VM is created:

  • Start up the new free5gc VM, and use the same username and password to log in.
  • In the Ubuntu terminal, issue ping and ifconfig again to make sure it has internet access, and also make note of the IP address of the Host-only network interface.
    • for example the IP could still be 192.168.56.101, and the interface name is enp0s8.
  • Log in into free5gc VM using SSH, and make sure all things working properly.

3. Change hostname

The cloned free5gc VM still has host name ubuntu (or the name you gave it in the original VM). Let’s rename the VM to free5gc. You can do this by editing the file /etc/hostname (using vi or nano):

sudo nano /etc/hostname
# or 
sudo vi /etc/hostname

In the file, change ubuntu into free5gc. If you are using nano ，you can press Ctrl-O to save the file, then Ctrl-X to exit.

Let’s also change the file /etc/hosts by replacing the ubuntu inside into free5gc:

sudo nano /etc/hosts

New content of the file /etc/hosts looks like this:

127.0.0.1 localhost
127.0.1.1 free5gc
...

The changes will take effect after next reboot.

4. Setting Static IP Address

The Host-only network interface, by default, gets its IP address through DHCP. The cloned free5gc VM seems to have trouble obtaining new IP address. We can change the host-only interface to use static IP address instead, which can save a lot of trouble later.

Here let’s fix the static IP address as 192.168.56.101:

$ cd /etc/netplan
$ ls
00-installer-config.yaml
$ cat 00-installer-config.yaml

The original content of the file 00-installer-config.yaml looks like:
# This is the network config written by 'subiquity'
network:
  ethernets:
    enp0s3:
      dhcp4: true
    enp0s8:
      dhcp4: true
  version: 2

meaning the VM has two network interfaces. Using ifconfig we know that enp0s8 is the name of the Host-only network interface. We can edit the file:
sudo nano 00-installer-config.yaml

and change it into:
# This is the network config written by 'subiquity'
network:
  ethernets:
    enp0s3:
      dhcp4: true
    enp0s8:
      dhcp4: no
      addresses: [192.168.56.101/24]
  version: 2

First check if the new content is correct:
sudo netplan try

Press enter to exit, if successful. The apply tne new interface setting:
sudo netplan apply

Run ifconfig to see if the network setting has been changed correctly:
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.0.2.15  netmask 255.255.255.0  broadcast 10.0.2.255
        inet6 fe80::a00:27ff:fec4:254f  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:c4:25:4f  txqueuelen 1000  (Ethernet)
        RX packets 2  bytes 1180 (1.1 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 18  bytes 1894 (1.8 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.56.101  netmask 255.255.255.0  broadcast 192.168.56.255
        inet6 fe80::a00:27ff:fe7e:ada6  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:7e:ad:a6  txqueuelen 1000  (Ethernet)
        RX packets 8420  bytes 531867 (531.8 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 10887  bytes 823487 (823.4 KB)
        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 6621  bytes 596035 (596.0 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 6621  bytes 596035 (596.0 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

We can also check the routing table, just to have a grasp of what is going on regarding the network setting:
$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.0.2.2        0.0.0.0         UG    100    0        0 enp0s3
10.0.2.0        0.0.0.0         255.255.255.0   U     0      0        0 enp0s3
10.0.2.2        0.0.0.0         255.255.255.255 UH    100    0        0 enp0s3
192.168.56.0    0.0.0.0         255.255.255.0   U     0      0        0 enp0s8

For the display above, we learn that the Host-only network 192.168.56.0/24 does not have internet access by itself (even though we can access it using SSH from the host machine). Internet access is through the NAT network 10.0.2.0/24, with the gateway being 10.0.2.2 (provided by VirtualBox).
Now we can SSH into free5gc VM using 192.168.56.101:

ssh 192.168.56.101 -l ubuntu

This is also how we interact with free5gc VM from now on.