Node1, node2 install package: (new mariadb package from own repository)

 apt-get install mariadb-server rsync mariadb-client

Master node:

nano /etc/mysql/mariadb.conf.d/60-galera.cnf

[galera]
# Mandatory settings
# Server Configuration
log_error                = mariadbd.err
innodb_buffer_pool_size  = 1G

wsrep_on                 = ON
wsrep_cluster_name       = "TEST Galera Cluster"
wsrep_provider           = /usr/lib/libgalera_smm.so
wsrep_cluster_address    = gcomm://192.168.3.201,192.168.3.202
binlog_format            = ROW
default_storage_engine   = InnoDB
innodb_autoinc_lock_mode = 2

# Allow server to accept connections on all interfaces.
bind-address = 0.0.0.0

# Optional settings
wsrep_slave_threads = 1
innodb_flush_log_at_trx_commit = 0
wsrep_node_name="db1"
wsrep_node_address="192.168.3.201"

sudo systemctl stop mariadb
sudo galera_new_cluster

Test galera:

mysql -u root -p -e "show status like 'wsrep_cluster_size'"

OUTPUT:

+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 1     |
+--------------------+-------+

NODE2:

nano /etc/mysql/mariadb.conf.d/60-galera.cnf

[galera]
# Mandatory settings
# Server Configuration
log_error                = mariadbd.err
innodb_buffer_pool_size  = 1G

wsrep_on                 = ON
wsrep_cluster_name       = "TEST Galera Cluster"
wsrep_provider           = /usr/lib/libgalera_smm.so
wsrep_cluster_address    = gcomm://192.168.3.201,192.168.3.202
binlog_format            = ROW
default_storage_engine   = InnoDB
innodb_autoinc_lock_mode = 2

# Allow server to accept connections on all interfaces.
bind-address = 0.0.0.0

# Optional settings
wsrep_slave_threads = 1
innodb_flush_log_at_trx_commit = 0
wsrep_node_name="db1"
wsrep_node_address="192.168.3.201"

sudo systemctl restart mariadb

test:

mysql -u root -p -e "show status like 'wsrep_cluster_size'"

OUTPUT:

+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 2     |
+--------------------+-------+