Let’s say you have an old dedicated server without AES-NI and you need 200 devices connected to it, but they only route traffic for a web server and a file server on your private network, and about 50% will be actively using the connection, and 50% will be idling, at any given time. As in the previous example this will of course vary somewhat as some users are working on other tasks and alternate this with retrieving files and data through the VPN tunnel. Let’s say you want to make sure each active users will have 10Mbps available, and let’s again assume they actually have that bandwidth on their Internet connection.
100 active users times 10Mbps is 1000Mbps or 1Gbps. Most systems nowadays have this by default, even servers that are several years old. 1000Mbps time 40MHz is about 40000MHz or 40GHz. Older servers with a dual octa-core setup with 2.5GHz will be able to get you to those requirements. With 200 connected devices in this example you would need about 2GB of memory, a fairly low amount.
PiVPN
curl -L https://install.pivpn.io | bash
mkdir /etc/openvpn/ccd
systemctl restart openvpn
tail -f /var/log/openvpn.log
Knowledge
apt install ufw
apt install nmap
apt install telnet
ufw status
netstat -a
netstat -lpn
nmap localhost
nc -v 10.19.83.204 80
nc -uv localhost 1194
nc -v 10.19.83.204 1194
netstat -uap|grep openvpn
tail -f /var/log/openvpn.log
nano /etc/openvpn/server.conf
telnet localhost 1194
telnet nas0.dev.shahed.biz 80
telnet nas0.dev.shahed.biz 1194
rm -f /etc/openvpn/pki/reqs/dev.shahed.biz.req
apt purge openmediavault-openvpn
rm -rf /opt/EasyRSA-v3.0.6/
rm -rf /etc/openvpn/
sysctl -w net.ipv4.tcp_window_scaling=0
References