Advanced SoftEther VPN Security Best Practices Print

Hello there! I’m Corels from Emmanuel Corels Creatives, and today we’re focusing on securing your SoftEther VPN Server with advanced best practices. In this guide, we’ll cover certificate management, robust firewall configurations, and additional security measures to ensure that your VPN environment remains resilient against threats. Let’s dive in and strengthen your VPN’s security step by step.

1. Strengthening Certificate Security

Certificates are the backbone of VPN security, ensuring encrypted communication and verifying server identity. Here are some key steps to bolster your certificate management:

• Generate a Robust Certificate:
  Use vpncmd to create a new certificate with a strong key size. For example:

  CertificateCreate ovpn-secure-cert /COMMONNAME:"vpn.yourdomain.com" /KEYSIZE:2048
  

  • COMMONNAME: Use your fully qualified domain name (FQDN) so clients can verify the server identity.
  • KEYSIZE: A 2048-bit key is standard; if you need extra security and your hardware permits, consider 4096 bits.

• Sign Your Certificate:
  Once generated, sign it with a set lifetime to ensure it remains valid:

  CertificateSign ovpn-secure-cert /LIFETIME:365
  

  This creates a certificate valid for one year. Renew and re-sign as needed.

• Export for Clients (When Needed):
  Export the certificate and private key to distribute to clients securely:

  CertificateExport ovpn-secure-cert /EXPORTPASS:"YourExportPass"
  

  Always keep your export passphrase secure and share exported files only over trusted channels.

2. Enforcing Strong VPN Protocol Settings

SoftEther VPN supports multiple protocols; for robust security, consider enabling protocols that leverage strong encryption. Here’s how to reinforce security in your OpenVPN or L2TP/IPsec setups:

• OpenVPN Settings:
  When enabling OpenVPN, ensure the server uses strong ciphers and authentication methods. For example, in vpncmd:

  OpenVpnEnable
  

  When prompted, select TCP (if your environment requires it) and choose options like:

  • Cipher: AES-256-CBC
  • Authentication: SHA256 (if supported) or SHA1 as a minimum.
    Match these settings in your client configuration file.

• L2TP/IPsec Settings:
  Ensure that IPsec is enabled with a strong pre-shared key. When configuring the L2TP server, use:

  L2tpEnable
  

  And set the IPsec secret to a robust value:

  MyStrongIPsecSecret!
  

  Consistency is key—ensure that the shared secret is identical on both server and client sides.

3. Implementing Robust Firewall Policies

Proper firewall configurations are critical to protect your SoftEther VPN Server from unauthorized access and attacks. Consider these practices:

• Allow Only Essential Ports:
  Limit incoming connections to those ports necessary for your VPN protocols. For instance, if using OpenVPN on TCP port 1194:

  /ip firewall filter add chain=input protocol=tcp dst-port=1194 action=accept comment="Allow OpenVPN"
  

• Block Unsolicited Traffic:
  Place a default “drop” rule after your allow rules to block any unsolicited traffic:

  /ip firewall filter add chain=input action=drop comment="Drop all other traffic"
  

• Restrict Management Access:
  Limit access to your SoftEther management interface (whether via vpncmd or GUI) by allowing only trusted IP addresses:

  /ip firewall filter add chain=input protocol=tcp dst-port=5555 src-address=192.168.1.50 action=accept comment="Allow management from trusted host"
  /ip firewall filter add chain=input protocol=tcp dst-port=5555 action=drop comment="Block management access from others"
  

  Adjust the IP range as needed.

• Enable Logging on Critical Rules:
  For key firewall rules, enable logging to monitor unauthorized access attempts:

  /ip firewall filter add chain=input protocol=tcp dst-port=1194 action=accept log=yes log-prefix="VPN-Access: " comment="Allow and log OpenVPN"
  

4. Regular Monitoring and Maintenance

Security is not a one-time setup; continuous monitoring is vital:

• Monitor Logs:
  Regularly check logs using:

  /log print
  

  This helps you spot unusual activity such as repeated failed login attempts or unexpected traffic.

• Update Software Promptly:
  Keep your SoftEther VPN Server and underlying operating system updated to protect against known vulnerabilities.

• Automate Routine Checks:
  Use scripts to automatically verify that critical services (like VPN sessions and firewall rules) are running as expected. For example, a script to monitor active VPN sessions can alert you if connections drop unexpectedly.

Final Thoughts

By following these advanced security best practices, you’re reinforcing the integrity of your SoftEther VPN Server. Effective certificate management, strong protocol settings, robust firewall rules, and proactive monitoring together create a secure environment that protects your network from unauthorized access and potential threats.

Take the time to test these configurations and adjust them to suit your specific requirements. If you have any questions or need further assistance, feel free to reach out. Here’s to a secure and resilient VPN setup!

Explained with clarity by
Corels – Admin, Emmanuel Corels Creatives