Konfigurasi openvpn server di Linux Debian

- March 13, 2026

Konfigurasi openvpn server di Linux Debian dapat mengikuti langkah berikut:

# apt update && apt install openvpn

# sed -i 's/#AUTOSTART="all"/AUTOSTART="all"/' /etc/default/openvpn

# cd /etc/openvpn/
# /usr/share/easy-rsa/easyrsa init-pki
# cp -a /usr/share/easy-rsa/vars.example /etc/openvpn/pki/vars
# vi /etc/openvpn/pki/vars

# In how many days should the root CA key expire?
set_var EASYRSA_CA_EXPIRE       3650

# In how many days should certificates expire?
set_var EASYRSA_CERT_EXPIRE     1825

# How many days until the Certificate Revokation List will expire.
#
# IMPORTANT: When the CRL expires, an OpenVPN Server which uses a
# CRL will reject ALL new connections, until the CRL is replaced.
#
set_var EASYRSA_CRL_DAYS        1095

# Choose a size in bits for your keypairs. The recommended value is 2048.
# Using 2048-bit keys is considered more than sufficient for many years into
# the future. Larger keysizes will slow down TLS negotiation and make key/DH
# param generation take much longer. Values up to 4096 should be accepted by
# most software. Only used when the crypto alg is rsa, see below.
set_var EASYRSA_KEY_SIZE        4096

# /usr/share/easy-rsa/easyrsa build-ca nopass

# /usr/share/easy-rsa/easyrsa build-server-full server nopass

# /usr/share/easy-rsa/easyrsa gen-dh

# /usr/share/easy-rsa/easyrsa build-client-full client01 nopass

# /usr/share/easy-rsa/easyrsa gen-dh

# for i in $(seq -w 1 10);do /usr/share/easy-rsa/easyrsa build-client-full client"$i" nopass; done

port 1194
proto udp
dev tun

ca /etc/openvpn/pki/ca.crt
cert /etc/openvpn/pki/issued/server.crt
key /etc/openvpn/pki/private/server.key # the server.key private key must be kept secret
dh /etc/openvpn/pki/dh.pem

# internal tun0 connection IP
server 10.10.25.0 255.255.255.0

ifconfig-pool-persist ipp.txt

keepalive 10 120

# Compression - must now be turned off for security reasonfor security reasons.
# Use compress stub-v2 if needed in place
#comp-lzo

persist-key
persist-tun

# parameters to be adjusted according to your network configuration
#push "dhcp-option DNS 172.18.0.250"
push "dhcp-option DOMAIN std.local"
push "route 172.18.0.0 255.255.252.0"
#push "redirect-gateway autolocal"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
#push "route 10.10.25.0 255.255.255.0"
#push "redirect-gateway def1"
#push "redirect-gateway local def1 bypass-dhcp"
#push "redirect-gateway def1 bypass-dhcp"
push "redirect-gateway local def1 bypass-dhcp"
status /var/log/openvpn-status.log
push "block-outside-dns"

# verbose mode
verb 3

# systemctl edit openvpn@server.service

tambahkan baris berikut ke file /etc/nftables.conf

#!/usr/sbin/nft -f

flush ruleset

table inet filter {
        chain input {
                type filter hook input priority 0;
        }
        chain forward {
                type filter hook forward priority 0;
        }
        chain output {
                type filter hook output priority 0;
        }
}
table ip NAT {
        chain my_masquerade {
                type nat hook postrouting priority 100; policy accept;
                ip saddr { 10.10.25.0/24 } oifname "enp3s0" masquerade comment "outgoing NAT"
        }
}

Selanjutnya aktipkan nftables.service

# systemctl enable nftables.service

Tambahkan forward=1 di file /etc/sysctl.d/99-ipforward.conf

net.ipv4.ip_forward=1

selanjutkan aktipkan ip forward diatas dengan perintah dibawah

# sysctl -p /etc/sysctl.d/99-ipforward.conf

aktipkan juga openvpn@server.service dan restart

# systemctl enable --now openvpn@server.service

# systemctl restart openvpn@server.service

cek apakah tun sudah aktip

#ip addr sh

hasilnya seperti dibawah

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute
       valid_lft forever preferred_lft forever
2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 9c:5c:8e:02:51:8c brd ff:ff:ff:ff:ff:ff
    altname enx9c5c8e02518c
    inet 172.18.0.250/22 brd 172.18.3.255 scope global dynamic noprefixroute enp3s0
       valid_lft 565sec preferred_lft 490sec
    inet6 fe80::7dc:1797:b9c7:57dd/64 scope link
       valid_lft forever preferred_lft forever
3: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 500
    link/none
    inet 10.10.25.1 peer 10.10.25.2/32 scope global tun0
       valid_lft forever preferred_lft forever
    inet6 fe80::4d30:520e:22bb:ff94/64 scope link stable-privacy proto kernel_ll
       valid_lft forever preferred_lft forever
4: ztppizrecu: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 2800 qdisc fq_codel state UNKNOWN group default qlen 1000
    link/ether 4a:f2:6e:f3:c5:17 brd ff:ff:ff:ff:ff:ff
    inet 10.10.11.250/24 brd 10.10.11.255 scope global ztppizrecu
       valid_lft forever preferred_lft forever
    inet6 fe80::48f2:6eff:fef3:c517/64 scope link proto kernel_ll
       valid_lft forever preferred_lft forever

copy semua file yang diperlukan untuk koneksi dari client ke server openvpn

 cp /etc/openvpn/pki/ca.crt /root/
 cp /etc/openvpn/pki/issued/client01.crt /root/
 cp /etc/openvpn/pki/private/client01.key /root/

buatkan file koneksi dari client

vi /root/client01.ovpn

isikan file seperti dibawah, sesuaikan dengan keperluan.

client

dev tun

proto udp

remote OPENVPN_IP 1194

resolv-retry infinite
nobind
persist-key
persist-tun

ca ca.crt
cert client01.crt
key client01.key

# disabled for security, use compress stub-v2 if needed in place
#comp-lzo

verb 3

Buka Windows explorer dan tempatkan file diatas ke folder C:\Users\tampu\OpenVPN\config