While SSTP (Secure Socket Tunneling Protocol) is tightly integrated with Windows, OpenVPN's cross-platform design offers greater flexibility. OpenVPN operates at Layer 3 (tunneling IP packets) while SSTP works at Layer 5 (encapsulating PPP frames). This fundamental difference impacts deployment scenarios:

# OpenVPN server configuration example (UDP-based)
proto udp
port 1194
dev tun
tls-server
dh dh2048.pem
ca ca.crt
cert server.crt
key server.key
cipher AES-256-CBC
auth SHA256

Though both protocols can traverse firewalls, OpenVPN provides multiple options:

• Can run on any port (including 443/TCP to mimic HTTPS)
• Supports both UDP (better performance) and TCP (firewall-friendly)
• Offers obfuscation techniques through plugins like obfsproxy

OpenVPN uses OpenSSL for cryptography, while SSTP relies on Microsoft's implementation. Key differences:

// SSTP connection establishment (Windows PowerShell)
Add-VpnConnection -Name "CorporateVPN" -ServerAddress "vpn.example.com" 
-TunnelType "Sstp" -EncryptionLevel "Required" -SplitTunneling $true

OpenVPN supports more cipher options and perfect forward secrecy (PFS) by default through ephemeral key exchange.

For Windows-only environments, OpenVPN still offers advantages:

• Centralized management through configuration files
• Better logging and monitoring capabilities
• Client verification through certificates + multi-factor authentication
• Support for load balancing across multiple servers

In our tests with Windows 10 clients (100Mbps connection):

While SSTP (Secure Socket Tunneling Protocol) is tightly integrated with Windows via its HTTPS-based tunneling, OpenVPN offers cross-platform compatibility through its custom TLS implementation. Consider this PowerShell snippet to check SSTP availability:

Get-WindowsFeature -Name Routing | Where-Object {$_.Name -match "SSTP"}

OpenVPN's configuration flexibility becomes evident when implementing custom encryption:

# OpenVPN config snippet showing AES-256-GCM + TLS 1.3
cipher AES-256-GCM
tls-version-min 1.3
tls-cipher TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384

Microsoft's SSTP implementation relies on Windows' certificate store and SSPI, while OpenVPN maintains its own cryptographic stack:

// SSTP authentication flow (simplified)
using System.Net.Security;
var sslStream = new SslStream(networkStream);
sslStream.AuthenticateAsClient(hostname);

OpenVPN's security advantage manifests in:

• Independent security audits (unlike proprietary SSTP)
• FIPS 140-2 validated modules via OpenSSL
• Support for modern algorithms (e.g., ChaCha20-Poly1305)

For Windows-only environments, SSTP offers simplicity:

# Enabling SSTP via Group Policy
Computer Configuration -> Policies -> Windows Settings -> Security Settings -> Network List Manager Policies

But OpenVPN scales better for hybrid environments:

# Sample OpenVPN client.ovpn for Windows
client
dev tun
proto tcp
remote vpn.example.com 443
resolv-retry infinite
auth-user-pass

Our tests on Windows Server 2022 showed:

While both protocols handle NAT well, OpenVPN offers more fallback options:

# OpenVPN TCP fallback configuration
remote vpn.example.com 1194
remote vpn.example.com 443
proto tcp
proto udp
remote-random

Compare with SSTP's single-port dependency:

netsh interface sstp set port 443