Install forticlient in linux. Replace HOST, PORT, USER and PASS.

install_forticlientsslvpn_linux

sudo apt-get install expect
wget https://hadler.me/files/forticlient-sslvpn_4.4.2333-1_amd64.deb
sudo dpkg -i forticlient-sslvpn_4.4.2333-1_amd64.deb

/opt/forticlient-sslvpn/64bit/helper/setup


cat > sslvpn << EOF
#!/usr/bin/expect -f

set hostandport [lindex \$argv 0];
set user [lindex \$argv 1];
set pass [lindex \$argv 2];

set timeout -1

cd /opt/forticlient-sslvpn/64bit/
spawn ./forticlientsslvpn_cli --server \$hostandport --vpnuser \$user --keepalive

expect "Password for VPN:" {send -- "\$pass\r"}
expect "to this server? (Y/N)\r" {send -- "y\r"}

expect eof
EOF
chmod +x sslvpn
sudo mv sslvpn /usr/local/bin/

vpn-site-abc.service

# please try with Ubuntu.

[Unit]
Description=SSL VPN connection for the site ABC
Wants=network.target
After=network-online.target

[Service]
Restart=always
ExecStart=/usr/local/bin/sslvpn -d somehost:443 someuser somepw
ExecStop=/bin/kill $MAINPID
Type=simple
RestartSec=10
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=sslvpn-site-ABC

[Install]
WantedBy=multi-user.target default.target