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
vim /etc/pivpn/openvpn/setupVars.conf
PLAT=Raspbian
OSCN=buster
USING_UFW=0
pivpnforceipv6route=1
IPv4dev=wlan0
dhcpReserv=1
IPv4addr=10.19.83.103/24
IPv4gw=10.19.83.1
install_user=pi
install_home=/home/pi
VPN=openvpn
pivpnPROTO=udp
pivpnPORT=1194
pivpnDNS1=10.19.83.1
pivpnDNS2=10.19.83.100
pivpnSEARCHDOMAIN=dev.shahed.biz
pivpnHOST=vpn.shahed.biz
TWO_POINT_FOUR=0
pivpnENCRYPT=2048
USE_PREDEFINED_DH_PARAM=0
INPUT_CHAIN_EDITED=0
FORWARD_CHAIN_EDITED=0
INPUT_CHAIN_EDITEDv6=
FORWARD_CHAIN_EDITEDv6=
pivpnDEV=tun0
pivpnNET=10.20.30.0
subnetClass=24
pivpnenableipv6=0
ALLOWED_IPS=""
UNATTUPG=1
INSTALLED_PACKAGES=()
HELP_SHOWN=1
Server
vim /etc/openvpn/server.conf
: <<'END_COMMENT'
dev tun
proto udp
port 1194
ca /etc/openvpn/easy-rsa/pki/ca.crt
cert /etc/openvpn/easy-rsa/pki/issued/pi03_cd0b38fd-1194-4fc2-b8e8-284b04ad0d02.crt
key /etc/openvpn/easy-rsa/pki/private/pi03_cd0b38fd-1194-4fc2-b8e8-284b04ad0d02.key
dh /etc/openvpn/easy-rsa/pki/dh2048.pem
topology subnet
server 10.20.30.0 255.255.255.0
# Set your primary domain name server address for clients
push "dhcp-option DOMAIN dev.shahed.biz"
push "dhcp-option DNS 10.19.83.1"
push "dhcp-option DNS 10.19.83.100"
# Prevent DNS leaks on Windows
push "block-outside-dns"
# Override the Client default gateway by using 0.0.0.0/1 and
# 128.0.0.0/1 rather than 0.0.0.0/0. This has the benefit of
# overriding but not wiping out the original default gateway.
push "redirect-gateway def1 bypass-dhcp"
client-to-client
client-config-dir /etc/openvpn/ccd
keepalive 15 120
remote-cert-tls client
tls-version-min 1.2
tls-auth /etc/openvpn/easy-rsa/pki/ta.key 0
cipher AES-256-CBC
auth SHA256
user openvpn
group openvpn
persist-key
persist-tun
crl-verify /etc/openvpn/crl.pem
status /var/log/openvpn-status.log 20
status-version 3
syslog
verb 3
#DuplicateCNs allow access control on a less-granular, per user basis.
#Remove # if you will manage access by user instead of device.
#duplicate-cn
# Generated for use by PiVPN.io
END_COMMENT
openssl dhparam -out /etc/openvpn/easy-rsa/pki/dh1024.pem 1024
openssl dhparam -out /etc/openvpn/easy-rsa/pki/dh2048.pem 2048
sudo systemctl start openvpn@server.service
sudo systemctl status openvpn@server.service
Client
pivpn add -n shahed_note
: <<'EOC'
How many days should the certificate last? 1080
Enter the password for the client:
Enter the password again to verify:
--more-skipped--
========================================================
Done! shahed_note.ovpn successfully created!
shahed_note.ovpn was copied to:
/home/pi/ovpns
for easy transfer. Please use this profile only on one
device and create additional profiles for other devices.
========================================================
EOC
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ls -lah /home/pi/ovpns/*.ovpn
ls -lah /etc/openvpn/easy-rsa/pki/reqs/*.req
ls -lah /etc/openvpn/easy-rsa/pki/issued/*.crt
ls -lah /etc/openvpn/easy-rsa/pki/private/*.key
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stat -c '%a %n' /home/pi/ovpns/*.ovpn
chmod 644 /home/pi/ovpns/*.ovpn
chmod 640 /home/pi/ovpns/*.ovpn
stat -c '%a %n' /home/pi/ovpns/*.ovpn
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ln -s /home/pi/ovpns/shahed_note.ovpn\
/var/shahed/www/vpn.shahed.biz/docs/comn/ovpns/shahed_note.ovpn
https://vpn.shahed.biz/docs/comn/ovpns/
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Debug
mkdir /etc/openvpn/ccd
systemctl restart openvpn
tail -f /var/log/openvpn.log
sysctl -w net.ipv4.ip_forward=1
nc -uv 10.20.13.1 1194
nc -uv 10.19.83.103 1194
nc -uv 10.19.83.203 1194
nc -uv vpn.shahed.biz 1194
nc -uv vpn0.dev.shahed.biz 1194
Connect
NAT Route
vim /etc/sysctl.conf
# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1
sudo sysctl -p
net.ipv4.ip_forward = 1
ip route | grep default
default via 10.19.83.1 dev wlan0 proto dhcp src 10.19.83.103 metric 303
sudo vim /etc/ufw/before.rules
# rules should be added to one of these chains:
# ufw-before-input
# ufw-before-output
# ufw-before-forward
#
# Start OpenVPN Rules
# NAT table rules
*nat
:POSTROUTING ACCEPT [0:0]
# Allow traffic from OpenVPN client to wlan0
-A POSTROUTING -s 10.20.30.0/24 -o wlan0 -j MASQUERADE
COMMIT
# End OpenVPN Rules
# Don't delete these required lines, otherwise there will be errors
*filter
vim /etc/ufw/sysctl.conf
# Uncomment this to allow this host to route packets between interfaces
net/ipv4/ip_forward=1
net/ipv6/conf/default/forwarding=1
net/ipv6/conf/all/forwarding=1
sudo vim /etc/default/ufw
# Set the default forward policy to ACCEPT, DROP or REJECT. Please note that
# if you change this you will most likely want to adjust your rules
DEFAULT_FORWARD_POLICY="ACCEPT"
sudo vim /lib/systemd/system/ufw.service
[Unit]
Description=Uncomplicated firewall
Documentation=man:ufw(8)
DefaultDependencies=no
Before=network.target
After=netfilter-persistent.service
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/lib/ufw/ufw-init start quiet
ExecStop=/lib/ufw/ufw-init stop
[Install]
WantedBy=multi-user.target
sudo ufw allow http
sudo ufw allow OpenSSH
sudo ufw allow 1194/udp
systemctl status ufw
sudo ufw disable
sudo ufw enable
sudo systemctl start openvpn@server
sudo systemctl status openvpn@server
ip addr show tun0
:'
5: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 100
link/none
inet 10.20.30.1/24 brd 10.20.30.255 scope global tun0
valid_lft forever preferred_lft forever
inet6 fe80::ab3a:dcac:98ba:b7a/64 scope link stable-privacy
valid_lft forever preferred_lft forever
'
ufw status verbose
: <<'EOC'
Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), allow (routed)
New profiles: skip
To Action From
-- ------ ----
22/tcp ALLOW IN Anywhere
1194 ALLOW IN Anywhere
80/tcp ALLOW IN Anywhere
1194/udp ALLOW IN Anywhere
22/tcp (OpenSSH) ALLOW IN Anywhere
22/tcp (v6) ALLOW IN Anywhere (v6)
1194 (v6) ALLOW IN Anywhere (v6)
80/tcp (v6) ALLOW IN Anywhere (v6)
1194/udp (v6) ALLOW IN Anywhere (v6)
22/tcp (OpenSSH (v6)) ALLOW IN Anywhere (v6)
Anywhere on wlan0 ALLOW FWD Anywhere on tun0
10.19.83.0/24 ALLOW FWD 10.8.0.0/24
Anywhere (v6) on wlan0 ALLOW FWD Anywhere (v6) on tun0
EOC
ufw status numbered
ufw status
Ubuntu Client
sudo apt install apt-transport-https\
ca-certificates curl software-properties-common
curl -fsSL https://swupdate.openvpn.net/repos/openvpn-repo-pkg-key.pub\
| sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/openvpn-repo-pkg-keyring.gpg
cat << EOF | sudo tee /etc/apt/sources.list.d/openvpn3.list >/dev/null
# OpenVPN 3 client - Ubuntu 22.04 LTS
deb [arch=$(dpkg --print-architecture)]\
https://swupdate.openvpn.net/community/openvpn3/repos $(lsb_release -cs) main
EOF
sudo apt update && sudo apt list --upgradeable
sudo apt upgrade && sudo apt install openvpn3
openvpn3 version
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openvpn3 config-import\
--name vpn.chorke.org\
--config ~/ovpns/chorke_ceo.ovpn
openvpn3 configs-list
openvpn3 config-remove\
--config vpn.chorke.org
openvpn3 config-remove\
--config ~/ovpns/chorke_ceo.ovpn
openvpn3 config-remove --path\
/net/openvpn/v3/configuration/65c57d54xbd4fx40aex9819x47ba0803d7c5
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openvpn3 session-start\
--config vpn.chorke.org
openvpn3 session-start\
--config ~/ovpns/chorke_ceo.ovpn
openvpn3 sessions-list
openvpn3 session-manage\
--disconnect --config vpn.chorke.org
openvpn3 session-manage --disconnect --config\
~/ovpns/chorke_ceo.ovpn
openvpn3 session-manage --disconnect --path\
/net/openvpn/v3/sessions/dab84ba8s3678s41d5saa61sf1515ffa690c
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[Unit]
Description=vpn.chorke.org
After=network.target
[Service]
Type=simple
Restart=always
WorkingDirectory=/home/academia/ovpns
ExecStart=/usr/sbin/openvpn --config vpn.chorke.org
[Install]
WantedBy=multi-user.target
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Linux Service
cat << EOF | sudo tee /etc/systemd/system/academia-vpn-dev.service >>/dev/null
[Unit]
Description=Academia OpenVPN Dev Client
After=network.target
[Service]
Restart=always
Type=simple
WorkingDirectory=/home/shahed/ovpns
ExecStart=/usr/sbin/openvpn --config academia-vpn-dev.ovpn
[Install]
WantedBy=multi-user.target
EOF
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sudo systemctl daemon-reload
sudo systemctl enable --now academia-vpn-dev
systemctl status academia-vpn-dev
sudo systemctl disable --now academia-vpn-dev
systemctl status academia-vpn-dev
sudo systemctl restart academia-vpn-dev
systemctl status academia-vpn-dev
sudo systemctl stop academia-vpn-dev
systemctl status academia-vpn-dev
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Knowledge
ufw status
netstat -a
netstat -lpn
pivpn add
pivpn list
pivpn revoke
pivpn -u # uninstall
apt install ufw
apt install nmap
apt install telnet
apt list --installed
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netstat -uap|grep openvpn
tail -f /var/log/openvpn.log
nano /etc/openvpn/server.conf
nmap -sT vpn0.dev.shahed.biz
nmap -sU vpn0.dev.shahed.biz
nc -uv 10.20.13.1 1194
nc -uv 10.19.83.103 1194
nc -uv 10.19.83.203 1194
nc -uv vpn.shahed.biz 1194
nc -uv vpn0.dev.shahed.biz 1194
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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.ip_forward=1
sysctl -w net.ipv4.tcp_window_scaling=0
route add -net 10.20.30.0/24 gw 10.19.83.1 metric 1
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References