Installation - Part B Error

I’m trying to install Free5GC from here
I’ve gone through Part A and all seemed to go well. On Part B I got an Error:

ens4: ERROR while getting interface flags: No such device

Screenshot attached. Is this a problem? How can I check whether part B worked?


You can use “ip a”
ubuntu@ubuntu-KVM:~$ ip a
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 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 52:54:00:ae:cd:e1 brd ff:ff:ff:ff:ff:ff
inet brd scope global noprefixroute ens3
valid_lft forever preferred_lft forever
inet6 fe80::21c9:d928:f2a9:c201/64 scope link noprefixroute
valid_lft forever preferred_lft forever

Hi Whiddett,

You are installing free5GC stage1, the latest one is stage 3.
In case you also want to use stage 1, the issue is that you don’t have ens4 interface in your server.
In the guide, ens3 is used to connect to eNB, ens4 is used to connect to internet. So please make sure you have 2 interfaces and put interface name mapping to your server’s interface name.


Hi. I’m a little confused. I was installing Stage 1: All in One, thinking this was the full Free5GC installation. What is the difference between Stage 1 and Stage 3? How can I tell which one I need?


You can view the roadmap to understand more about stages.
The stage 3 is the latest version.

And you should go to its source code for the latest update :

Hi. Thanks for your comment. Perhaps you can advise further. Our plan is to build a comms network using Free5GC for the core network and a small cell providing access to UE.
Perhaps I should be installed Stage 3 but on the install pages is says ‘There are no gNB and UE for standalone 5GC available in the market yet.’ Does this mean it is not possible to use and test Stage 3? Or which stage should I be trying to use?


" There are no gNB and UE for standalone 5GC available in the market yet", this sentence was written several months ago, and it was not updated. If there is gNB and UE 5G, you can use with free5gc.

You should use the latest one - stage 3.

I’ve installed ubuntu 18.04 but the kernal version is 4.15.0-123-generic. Please can you help me with instructions to install kernal 5.0.0-23-generic as required by stage 3 free5gc?

You may reference to the wiki

Thank you calee. That was a great help.

I’m now looking at installing Go. I notice the instructions say to run:


I’m wondering is this command should be different dependent upon the computer processor in use? I have an Intel core i7, not an AMD. Or is this command fine as it is?

I’ve continued working through the Stage 3 installation assuming the amd64 command mentioned above is fine. At step ‘A 4 Network Setting’ I’ve run into a problem. When entering the command:
sudo iptables -t nat -A POSTROUTING -o <dn_interface> -j MASQUERADE
I get:
-bash: dn_interface: No such file or directory
Any ideas what is wrong or how to fix this please?

please replace <dn_interface> by your interface’s name
ex: sudo iptables -t nat -A POSTROUTING -o ens3 -j MASQUERADE


Thanks. How do I know my interface name?

Hi ahntrung87vn. Thanks for your help so far. I believe that I have now successfully installed Free5GC Stage 3. For the dn_interface I entered ens3 as you suggested and that didn’t give me any errors. However, I’ve not run the ‘ip a’ command which, if I understand correctly, displays my network interfaces. The items listed are: lo, enp0s3, enp0s8, emp0s9.
Does this mean I should have entered enp0s3 instead of ens3?

In ‘Run’ section B, the instructions ask for the following items: IKEBindAddress, IPSecInterfaceMark, IPSecInterfaceAddress/CIDRPrefix
What should I use in place of these items?


Hi whiddett,

Yes, you should enter enp0s3 or enp0s8 or enp0s9 that can access to internet. (dn_interface is data network interface)

According to Part B. I have not used N3IWF, so I have not configured it yet.

Thanks. Is it possible to avoid N3IWF config by choosing the all-in-one option?

Any idea on that please?

If you don’t use N3IWF, just ignore it part B. N3IWF is used for wifi AP that uses unlicensed spectrum to connect to it. All in one is a old stage, so please don’t use it.

Thank you.
When I try to run the core network I enter the command:

Some output appears on the screen without any apparent errors. However, the console does not return to a command prompt so I cannot enter commands to start carrying out testing. What should I do?

Hi Whiddett,

When running ./, it just starts all 5G core component and show logs, there will not be a command prompt. You have to open another session to execute test script.