Install Netopeer2 on Ubuntu 20.04 

sudo apt-get update
sudo apt-get install git cmake build-essential bison flex libpcre3-dev libev-dev libavl-dev libprotobuf-c-dev protobuf-c-compiler swig python-dev lua5.2 pkg-config libpcre++-dev openssl libssl-dev libcrypto++-dev zlib1g-dev

* Install libssh 0.8.6 since the system installed libssh0.9.3 won't work with Netopeer2

Install libssh 0.8.6
wget https://git.libssh.org/projects/libssh.git/snapshot/libssh-0.8.6.tar.gz
tar -xf libssh-0.8.6.tar.gz
rm libssh-0.8.6.tar.gz
cd libssh-0.8.6
mkdir build && cd build
cmake ..
make
sudo make install

On Ubuntu, become root:

sudo -i

mkdir NetConfServer
cd NetConfServer

1 Install libyang
git clone https://github.com/CESNET/libyang.git
cd libyang
mkdir build && cd build && cmake .. && make && make install

2 Install sysrepo
cd ..
git clone https://github.com/sysrepo/sysrepo.git
cd sysrepo
mkdir build && cd build && cmake .. && make && make install

3 Install libnetconf2
cd ..
git clone https://github.com/CESNET/libnetconf2.git
cd libnetconf2
mkdir build && cd build && cmake .. && make && make install


4 Install Netopeer2
cd ..
git clone https://github.com/CESNET/netopeer2.git
cd netopeer2
mkdir build && cd build && cmake .. && make && make install


To ensure that all libraries that have been installed are now available, execute:

ldconfig


Testing
The simplest check to see if netopeer2-server installed correctly is to run it with the -h (help) option:

$ netopeer2-server -h
Usage: netopeer2-server [-dhV] [-v level] [-c category]
-d debug mode (do not daemonize and print
verbose messages to stderr instead of syslog)
-h display help
-V show program version
-v level verbose output level:
0 - errors
1 - errors and warnings
2 - errors, warnings and verbose messages
-c category[,category]* verbose debug level, print only these debug message categories
categories: DICT, YANG, YIN, XPATH, DIFF, MSG, EDIT_CONFIG, SSH, SYSREPO

You should confirm that sysrepo is installed and runnable:

$ sysrepoctl -l
Sysrepo schema directory: /etc/sysrepo/yang/
Sysrepo data directory: /etc/sysrepo/data/
(Do not alter contents of these directories manually)
List of Module Names

Start netopeer processes:

$ sudo netopeer2-server

You may want to start netopeer2-server in debug mode:

$ sudo netopeer2-server -d -v3


$ netopeer2-cli
> connect
Interactive SSH Authentication
Type your password:
Password:
>
Shell
and also check the running configuration:

> get-config --source running

Connect to netopeer server from NETCONFc

Start NETCONFc, click the 'Connect SSH' toolbar button, enter server’s host name or IP address, port number, user name and password. By default you should be able to use any SSH user configured in your Ubunto box to connect to it. Later you can enable NACM settings to restrict access.

Then click the button “Connect” on the session creation dialog. You should be connected to the server. If error happens, check if the server is running on the specified address and port. Also make sure the correct user name and password are used. See more in troubleshooting section.

For details on how to create a session from NETCONFc and browse default modules on netopeer server, see NETCONFc's menu Help->Help Topics ->First steps with NETCONFc