The 2025 Ultimate VPN Guide: From Traditional VPNs to Zero Trust Network Access

Introduction

Five years have passed since our 2020 article, and VPN technology has evolved significantly. This guide provides a clear and easy-to-understand explanation of the latest trends in VPN technology and more secure, efficient network access methods, even for beginners.

The State of VPN Technology in 2025

Key Changes

1. End of Support for CentOS 7 (June 30, 2024)
   • Migration to Rocky Linux, AlmaLinux, or Ubuntu LTS is recommended.
2. Rise of New VPN Protocols
   • Widespread adoption of WireGuard (4x faster than OpenVPN).
   • Emergence of QUIC-based VPNs.
3. Standardization of Zero Trust Architecture
   • A shift away from traditional perimeter-based security.
   • Emphasis on continuous authentication and the principle of least privilege.

Installing and Configuring the Latest Version of SoftEther VPN

System Requirements (2025 Recommendations)

• OS: Rocky Linux 9, AlmaLinux 9, Ubuntu 24.04 LTS
• CPU: 64-bit processor (ARM64 compatible)
• Memory: 2GB or more
• Storage: 20GB or more

Setup Guide for Rocky Linux 9 / AlmaLinux 9

1. System Preparation

# Update the system
sudo dnf update -y

# Install necessary packages
sudo dnf groupinstall "Development Tools" -y
sudo dnf install wget curl gcc make cmake git \
    openssl-devel readline-devel ncurses-devel \
    zlib-devel libsodium-devel -y

# Temporarily disable SELinux (configure properly in a production environment)
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing/SELINUX=permissive/' /etc/selinux/config

# Configure Firewalld
sudo firewall-cmd --permanent --add-port=443/tcp
sudo firewall-cmd --permanent --add-port=5555/tcp
sudo firewall-cmd --permanent --add-port=1194/udp
sudo firewall-cmd --permanent --add-service=ipsec
sudo firewall-cmd --permanent --add-port=500/udp
sudo firewall-cmd --permanent --add-port=4500/udp
sudo firewall-cmd --permanent --add-port=1701/udp
sudo firewall-cmd --reload

2. Install SoftEther VPN Server v4.44

# Move to the temporary directory
cd /tmp

# Download the latest version (April 2025 release)
wget https://github.com/SoftEtherVPN/SoftEtherVPN_Stable/releases/download/v4.44-9807-rtm/softether-vpnserver-v4.44-9807-rtm-2025.04.16-linux-x64-64bit.tar.gz

# Extract the archive
tar xzf softether-vpnserver-v4.44-9807-rtm-2025.04.16-linux-x64-64bit.tar.gz

# Build
cd vpnserver
make

# Install
cd ..
sudo mv vpnserver /usr/local/
cd /usr/local/vpnserver
sudo chmod 600 *
sudo chmod 700 vpnserver vpncmd

3. Configure Systemd Service (Improved Version)

sudo cat > /etc/systemd/system/softether-vpnserver.service << 'EOF'
[Unit]
Description=SoftEther VPN Server v4.44
After=network-online.target
Wants=network-online.target

[Service]
Type=forking
ExecStart=/usr/local/vpnserver/vpnserver start
ExecStop=/usr/local/vpnserver/vpnserver stop
ExecReload=/bin/kill -HUP $MAINPID
Restart=on-failure
RestartSec=3s

# Security Hardening
PrivateTmp=yes
ProtectSystem=full
ProtectHome=yes
NoNewPrivileges=yes
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF

# Enable and start the service
sudo systemctl daemon-reload
sudo systemctl enable softether-vpnserver
sudo systemctl start softether-vpnserver

4. Initial Configuration (Command Line)

# Initial setup using vpncmd
sudo /usr/local/vpnserver/vpncmd

# Follow the interactive prompts for configuration
# 1. Set administrator password
ServerPasswordSet

# 2. Create a Virtual Hub
HubCreate MyVPN /PASSWORD:YourHubPassword

# 3. Create a user
Hub MyVPN
UserCreate testuser /GROUP:none /REALNAME:none /NOTE:none
UserPasswordSet testuser /PASSWORD:UserPassword123

# 4. Enable SecureNAT
SecureNatEnable

# 5. Configure L2TP/IPSec
IPsecEnable /L2TP:yes /L2TPRAW:no /ETHERIP:no \
  /PSK:YourPreSharedKey123 /DEFAULTHUB:MyVPN

Setup Guide for Ubuntu 24.04 LTS

# Update and upgrade the system
sudo apt update && sudo apt upgrade -y

# Install necessary packages
sudo apt install -y build-essential wget curl gcc make \
    libreadline-dev libncurses-dev libssl-dev zlib1g-dev

# Download and install SoftEther VPN
cd /tmp
wget https://github.com/SoftEtherVPN/SoftEtherVPN_Stable/releases/download/v4.44-9807-rtm/softether-vpnserver-v4.44-9807-rtm-2025.04.16-linux-x64-64bit.tar.gz
tar xzf softether-vpnserver-*.tar.gz
cd vpnserver
make
cd ..
sudo mv vpnserver /usr/local/

# Set permissions
cd /usr/local/vpnserver
sudo chmod 600 *
sudo chmod +x vpnserver vpncmd

# Create Systemd service file (same content as for Rocky Linux)
# Configure UFW firewall
sudo ufw allow 443/tcp
sudo ufw allow 5555/tcp
sudo ufw allow 1194/udp
sudo ufw allow 500/udp
sudo ufw allow 4500/udp
sudo ufw allow 1701/udp

WireGuard – The Next-Generation VPN Protocol

WireGuard Features

• Extremely Fast: About 4 times faster than OpenVPN.
• Simple: A lean codebase of around 4,000 lines (compared to OpenVPN’s 600,000).
• Modern Cryptography: Uses ChaCha20, Poly1305, Curve25519, BLAKE2.
• Low Latency: Operates at the kernel level.

Installing and Configuring WireGuard

Rocky Linux 9 / AlmaLinux 9

# Install WireGuard
sudo dnf install -y wireguard-tools

# Generate keys
wg genkey | sudo tee /etc/wireguard/server_private.key
sudo chmod 600 /etc/wireguard/server_private.key
sudo cat /etc/wireguard/server_private.key | wg pubkey | sudo tee /etc/wireguard/server_public.key

# Create server configuration file
sudo cat > /etc/wireguard/wg0.conf << 'EOF'
[Interface]
Address = 10.0.0.1/24
ListenPort = 51820
PrivateKey = <SERVER_PRIVATE_KEY>
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

[Peer]
# Client 1
PublicKey = <CLIENT_1_PUBLIC_KEY>
AllowedIPs = 10.0.0.2/32

[Peer]
# Client 2
PublicKey = <CLIENT_2_PUBLIC_KEY>
AllowedIPs = 10.0.0.3/32
EOF

# Start WireGuard
sudo systemctl enable --now wg-quick@wg0

WireGuard vs. OpenVPN vs. SoftEther Performance Comparison (2025)

Migrating to Zero Trust Network Access (ZTNA)

Core Principles of Zero Trust

1. Never Trust, Always Verify
2. Principle of Least Privilege
3. Continuous Verification
4. Micro-segmentation

Simple ZTNA Implementation with Tailscale

Tailscale is a mesh VPN based on WireGuard that makes it easy to implement Zero Trust principles.

Installation and Configuration

# Install Tailscale (Rocky Linux 9)
curl -fsSL https://tailscale.com/install.sh | sh

# Start and authenticate
sudo systemctl enable --now tailscaled
sudo tailscale up

# Configure ACLs (Access Control Lists)
# Set up via the web UI at tailscale.com/admin

Example Tailscale ACL Policy

{
  "acls": [
    {
      "action": "accept",
      "src": ["group:developers"],
      "dst": ["tag:production:*"]
    },
    {
      "action": "accept",
      "src": ["group:admins"],
      "dst": ["*:*"]
    }
  ],
  "groups": {
    "group:developers": ["user1@example.com", "user2@example.com"],
    "group:admins": ["admin@example.com"]
  },
  "tagOwners": {
    "tag:production": ["group:admins"]
  }
}

Other ZTNA Solutions

1. Cloudflare Zero Trust
   • Cloud-based ZTNA.
   • Integration with WAF.
   • Free plan for up to 50 users.
2. Zscaler Private Access
   • Enterprise-focused.
   • Comprehensive SASE platform.
3. Pomerium
   • Open-source.
   • Identity-Aware Proxy.
   • Kubernetes-native.

Containerized VPN Deployment

Deploying SoftEther VPN with Docker

Deployment with Docker Compose

# docker-compose.yml
version: '3.8'

services:
  softether-vpn:
    image: softethervpn/vpnserver:stable
    container_name: softether-vpn-server
    cap_add:
      - NET_ADMIN
    restart: unless-stopped
    ports:
      - "443:443/tcp"      # HTTPS/Management
      - "992:992/tcp"      # Alternative HTTPS
      - "5555:5555/tcp"    # SoftEther Protocol
      - "1194:1194/udp"    # OpenVPN
      - "500:500/udp"      # IPSec IKE
      - "4500:4500/udp"    # IPSec NAT-T
      - "1701:1701/udp"    # L2TP
    volumes:
      - ./vpn_server.config:/usr/vpnserver/vpn_server.config
      - ./server_log:/var/log/vpnserver
    environment:
      - SPW=ServerPassword123  # Server Admin Password
      - HPW=HubPassword123     # Hub Admin Password
      - PSK=PreSharedKey123    # L2TP/IPSec Pre-Shared Key

Startup Commands

# Start with Docker Compose
docker-compose up -d

# Check logs
docker-compose logs -f

# Execute admin commands
docker exec -it softether-vpn-server vpncmd

Deployment on Kubernetes

# softether-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: softether-vpn
  namespace: vpn
spec:
  replicas: 1
  selector:
    matchLabels:
      app: softether-vpn
  template:
    metadata:
      labels:
        app: softether-vpn
    spec:
      containers:
      - name: softether
        image: softethervpn/vpnserver:stable
        securityContext:
          capabilities:
            add:
            - NET_ADMIN
        ports:
        - containerPort: 443
          protocol: TCP
        - containerPort: 1194
          protocol: UDP
        - containerPort: 500
          protocol: UDP
        - containerPort: 4500
          protocol: UDP
        volumeMounts:
        - name: config
          mountPath: /usr/vpnserver/vpn_server.config
          subPath: vpn_server.config
        - name: logs
          mountPath: /var/log/vpnserver
      volumes:
      - name: config
        configMap:
          name: softether-config
      - name: logs
        emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
  name: softether-vpn-service
  namespace: vpn
spec:
  type: LoadBalancer
  selector:
    app: softether-vpn
  ports:
  - name: https
    port: 443
    targetPort: 443
    protocol: TCP
  - name: openvpn
    port: 1194
    targetPort: 1194
    protocol: UDP
  - name: ipsec-ike
    port: 500
    targetPort: 500
    protocol: UDP
  - name: ipsec-nat
    port: 4500
    targetPort: 4500
    protocol: UDP

Security Hardening Best Practices

1. Implement Multi-Factor Authentication (MFA)

# Integrate with a RADIUS authentication server
# Install FreeRADIUS
sudo dnf install -y freeradius freeradius-utils

# Configure Google Authenticator PAM module
sudo dnf install -y google-authenticator

2. Set Up Certificate-Based Authentication

# Create a CA certificate
openssl genrsa -out ca.key 4096
openssl req -new -x509 -days 3650 -key ca.key -out ca.crt

# Create a server certificate
openssl genrsa -out server.key 4096
openssl req -new -key server.key -out server.csr
openssl x509 -req -days 365 -in server.csr -CA ca.crt -CAkey ca.key -set_serial 01 -out server.crt

# Create a client certificate
openssl genrsa -out client.key 4096
openssl req -new -key client.key -out client.csr
openssl x509 -req -days 365 -in client.csr -CA ca.crt -CAkey ca.key -set_serial 02 -out client.crt

3. Log Monitoring and Alerting

# Configure Fail2ban (for brute-force attack protection)
sudo dnf install -y fail2ban
 
# Create a filter for SoftEther VPN
sudo tee /etc/fail2ban/filter.d/softether.conf > /dev/null <<'EOF'
[Definition]
failregex = ^.*Connection ".*" from <HOST>:[0-9]+ failed.*$
            ^.*User authentication failed.*from <HOST>.*$
ignoreregex =
EOF
 
# Configure the jail
sudo tee /etc/fail2ban/jail.d/softether.conf > /dev/null <<'EOF'
[softether]
enabled = true
port = 443,992,5555,1194
protocol = tcp
filter = softether
logpath = /usr/local/vpnserver/security_log/*.log
maxretry = 5
findtime = 600
bantime = 3600
EOF
 
sudo systemctl enable --now fail2ban

4. Network Segmentation

# Access control per Virtual Hub
# Example configuration with vpncmd
Hub MyVPN
AccessAdd pass 192.168.1.0/255.255.255.0 / /PRIORITY:100
AccessAdd deny 192.168.100.0/255.255.255.0 / /PRIORITY:90

5. Regular Security Audits

# Port scan with Nmap
nmap -sV -p- your-vpn-server.com

# Vulnerability scan with Lynis
lynis audit system

# Comprehensive security assessment with OpenVAS
# (Requires separate installation)

Client Configuration Guide (2025 Edition)

Windows 11 Setup

1. Download the Latest SoftEther VPN Client
   • Download v4.44 Build 9807 from the official website.
   • Confirmed to be compatible with Windows 11.
2. New Feature: Windows Hello Authentication
   • Connect using biometric authentication (fingerprint/face recognition).
   • Setup:1. Create a VPN connection setting. 2. In the "Authentication" tab, select "Windows Hello". 3. Complete the Windows Hello setup.

macOS Sonoma/Ventura Setup

# Install with Homebrew (recommended)
brew install softethervpn

# Or, use the native L2TP/IPSec connection
# System Settings > Network > VPN > Add VPN Configuration
# - Type: L2TP over IPSec
# - Server Address: your-server.com
# - Account Name: HubName\\Username
# - Password: YourPassword
# - Shared Secret: PreSharedKey

iOS 17 / iPadOS 17 Setup

1. Open the Settings app.
2. Go to “General” -> “VPN & Device Management” -> “VPN”.
3. Tap “Add VPN Configuration…”.
4. Enter the following:
   • Type: L2TP
   • Description: Any name
   • Server: Server IP or domain
   • Account: HubName\Username
   • Password: (save it)
   • Secret: Pre-Shared Key

Android 14 Setup

1. Go to Settings -> Network & internet -> VPN.
2. Tap “+” to create a new profile.
3. Configure the following:
   • Name: Any name
   • Type: L2TP/IPSec PSK
   • Server address: your-server.com
   • IPSec pre-shared key: YourPSK
   • Username: HubName\Username
   • Password: YourPassword
   • Forwarding routes: 0.0.0.0/0 (for all traffic)

Troubleshooting

Common Issues and Solutions

1. Cannot Connect

# Check ports
sudo ss -tunlp | grep vpnserver

# Check firewall
sudo firewall-cmd --list-all

# Check SELinux (Rocky Linux/AlmaLinux)
sudo ausearch -m avc -ts recent

# Check logs
sudo tail -f /usr/local/vpnserver/security_log/$(date +%Y%m%d).log

2. Slow Speed

# Optimize MTU size
sudo ip link set dev vpn_vpn mtu 1400

# TCP optimization
sudo sysctl -w net.core.rmem_max=134217728
sudo sysctl -w net.core.wmem_max=134217728
sudo sysctl -w net.ipv4.tcp_rmem="4096 87380 134217728"
sudo sysctl -w net.ipv4.tcp_wmem="4096 65536 134217728"

3. DNS Resolution Issues

# Configure SecureNAT DNS settings
Hub MyVPN
SecureNatHostSet /MAC:none /IP:192.168.30.1 /MASK:255.255.255.0
DhcpSet /START:192.168.30.10 /END:192.168.30.200 /MASK:255.255.255.0 /EXPIRE:7200 /GW:192.168.30.1 /DNS:8.8.8.8 /DNS2:1.1.1.1

Performance Tuning

1. Kernel Parameter Optimization

# /etc/sysctl.d/99-vpn-performance.conf
cat > /etc/sysctl.d/99-vpn-performance.conf << 'EOF'
# Increase network buffer sizes
net.core.rmem_max = 134217728
net.core.wmem_max = 134217728
net.core.netdev_max_backlog = 5000
net.ipv4.tcp_rmem = 4096 87380 134217728
net.ipv4.tcp_wmem = 4096 65536 134217728

# TCP optimization
net.ipv4.tcp_congestion_control = bbr
net.core.default_qdisc = fq
net.ipv4.tcp_notsent_lowat = 16384

# Increase connection limits
net.ipv4.ip_local_port_range = 1024 65535
net.core.somaxconn = 65535
net.ipv4.tcp_max_syn_backlog = 65535

# Security settings
net.ipv4.tcp_syncookies = 1
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
EOF

sudo sysctl -p /etc/sysctl.d/99-vpn-performance.conf

2. CPU Affinity Settings

# Pin VPN process to specific CPU cores
sudo taskset -cp 0-3 $(pidof vpnserver)

Monitoring and Metrics

Monitoring with Prometheus

# docker-compose.monitoring.yml
version: '3.8'

services:
  prometheus:
    image: prom/prometheus:latest
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
      - prometheus_data:/prometheus
    ports:
      - "9090:9090"
    command:
      - '--config.file=/etc/prometheus/prometheus.yml'
      - '--storage.tsdb.path=/prometheus'

  grafana:
    image: grafana/grafana:latest
    ports:
      - "3000:3000"
    volumes:
      - grafana_data:/var/lib/grafana
    environment:
      - GF_SECURITY_ADMIN_PASSWORD=admin123

  node_exporter:
    image: prom/node-exporter:latest
    ports:
      - "9100:9100"
    volumes:
      - /proc:/host/proc:ro
      - /sys:/host/sys:ro
      - /:/rootfs:ro
    command:
      - '--path.procfs=/host/proc'
      - '--path.sysfs=/host/sys'
      - '--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)'

volumes:
  prometheus_data:
  grafana_data:

Conclusion and Future Outlook

VPN Selection Guide for 2025

1. Small-Scale / Personal Use
   • WireGuard: Fastest and simplest.
   • Tailscale: For Zero Trust and easy setup.
2. Medium-Sized Businesses
   • SoftEther VPN: For multi-protocol support and compatibility.
   • OpenVPN + FreeRADIUS: A standard, robust configuration.
3. Large Enterprises
   • ZTNA Products (e.g., Zscaler, Cloudflare).
   • Integrated SASE Solutions.

Future Technology Trends (2025-2027)

1. AI-Driven Security
   • Automated anomaly detection.
   • Adaptive access control.
2. Transition to Quantum-Resistant Cryptography
   • Support for Post-Quantum Cryptography (PQC).
   • Hybrid cryptographic schemes.
3. Integration with 5G/6G
   • Network slicing.
   • Collaboration with edge computing.

Recommended Migration Path

graph LR
    A[Traditional VPN] --> B[WireGuard/Modern VPN]
    B --> C[ZTNA Adoption]
    C --> D[Full Zero Trust]
    
    A2[2020-2023] --> B2[2024-2025]
    B2 --> C2[2025-2026]
    C2 --> D2[2027+]

References and Resources

Official Documentation

• SoftEther VPN Project
• WireGuard Documentation
• NIST Zero Trust Architecture SP 800-207
• Tailscale Documentation

Community and Support

• SoftEther VPN User Forum
• r/VPN (Reddit)
• Stack Overflow – VPN Tags

Security Information

• CVE Database
• JPCERT/CC
• IPA Security Center

Final Words

VPN technology has evolved from a simple remote access tool into an integral part of a comprehensive security architecture. As of 2025, the transition from traditional VPNs to Zero Trust Network Access is accelerating, making it crucial to select the right technology based on your organization’s size and requirements.

We hope this guide helps you build a secure and efficient network environment.

Update History

• September 2025: First edition created.
• Added support for SoftEther VPN v4.44.
• Added explanation of Zero Trust Architecture.
• Detailed containerization methods.

Author’s Note: The content of this article is based on information available as of September 2025. Security technologies are constantly evolving, so we recommend checking for the latest information when implementing these solutions.