This guide walks you through deploying a secure SSTP (Secure Socket Tunneling Protocol) VPN server on AWS, using TLS/SSL certificates to provide encrypted connectivity over TCP port 443. It is aimed at site operators, enterprise IT teams, and developers who require a resilient, secure VPN with a dedicated IP on AWS. The approach uses an Ubuntu EC2 instance running an open-source SSTP server, Let’s Encrypt certificates, and AWS networking best practices.

Why SSTP on AWS?

SSTP encapsulates PPP frames inside an SSL/TLS channel over TCP port 443, making it highly suitable for traversing restrictive networks and firewalls. Windows clients have native SSTP support, and many third-party clients support it as well. Deploying SSTP on AWS gives you control over the server, a static public IP (Elastic IP), and integration with other AWS services.

Overview and prerequisites

High-level steps covered:

  • Provision EC2 instance and network resources (Elastic IP, Security Group).
  • Install and configure SSTP server (linux-sstp / sstp-server).
  • Obtain and configure TLS certificates from Let’s Encrypt.
  • Set up IP forwarding, NAT, and firewall rules.
  • Configure Windows clients and verify connectivity.

Prerequisites:

  • An AWS account with permissions to create EC2 instances, Elastic IPs, Security Groups, and modify route tables.
  • A domain name you control (for TLS certificate and easier client setup).
  • Basic Linux administration skills and familiarity with AWS console/CLI.

Step 1 — Provision the EC2 instance and networking

1. Create an EC2 instance:

  • AMI: Ubuntu LTS (e.g., 22.04).
  • Instance type: t3.small or larger (VPN encryption is CPU-bound).
  • Storage: 8–20 GB, depending on logging needs.
  • Key pair: choose an SSH key for administration.

2. Allocate an Elastic IP (EIP) and associate it with the EC2 instance so you have a stable public IP.

3. Security Group (essential ports):

  • TCP 22 — SSH (limit to trusted IPs)
  • TCP 443 — SSTP (allow from 0.0.0.0/0 or restrict to known clients)
  • ICMP (optional) — for ping/diagnostics
  • UDP port for administrative services only if required

4. Disable source/destination checks on the EC2 instance only if you plan to route traffic through it for other AWS subnets. For a simple internet-bound VPN this is not necessary.

Step 2 — Install SSTP server on Ubuntu

We’ll use sstp-server (aka linux-sstp) which implements SSTP on Linux. Connect to your EC2 via SSH and run:

sudo apt update && sudo apt upgrade -y

Install dependencies and the sstp server:

sudo apt install -y ppp git build-essential libssl-dev libreadline-dev

Clone and build the sstp-server (example project; ensure to use maintained fork):

git clone https://github.com/rofl0r/sstp-server.git
cd sstp-server
make && sudo make install

Note: project names and repos vary — if you prefer a packaged alternative, look for a maintained distro package or use a VPN stack like SoftEther which also supports SSTP.

PPP and authentication configuration

Configure PPP and users. Edit /etc/ppp/options.sstp or similar based on the server’s instruction. A minimal example:

noauth
nobsdcomp
nodefaultroute
mtu 1300
mru 1300
proxyarp

Create user credentials for PAP/CHAP authentication in /etc/ppp/chap-secrets (format: client server secret IPs):

# username server password IPs
vpnuser strongpassword

Restrict file permissions:

sudo chmod 600 /etc/ppp/chap-secrets

Step 3 — Obtain TLS/SSL certificate with Let’s Encrypt

SSTP requires an SSL certificate whose CN or SAN matches your domain. Use Certbot and the standalone plugin (stopping any process that listens on 80/443 temporarily) or DNS validation if you cannot stop services.

Install Certbot:

sudo apt install -y certbot

Example using standalone mode (ensure port 80 or 443 is free during issuance):

sudo systemctl stop nginx # if running
sudo certbot certonly --standalone -d vpn.example.com

Certbot will place certs in /etc/letsencrypt/live/vpn.example.com/ as fullchain.pem and privkey.pem.

Set proper permissions:

sudo chmod 640 /etc/letsencrypt/live/vpn.example.com/privkey.pem
sudo chown root:root /etc/letsencrypt/live/vpn.example.com/*

Automate renewal with cron or systemd timer — Certbot already installs a timer on many distributions. Ensure any service that needs the new cert re-reads it or is reloaded post-renewal.

Step 4 — Configure SSTP to use the certificate

Configure the SSTP daemon to use the certificate files. Depending on server implementation, you will reference:

  • /etc/letsencrypt/live/vpn.example.com/fullchain.pem
  • /etc/letsencrypt/live/vpn.example.com/privkey.pem

Example sstp-server config snippet (adjust to your server’s format):

tls_cert = /etc/letsencrypt/live/vpn.example.com/fullchain.pem
tls_key = /etc/letsencrypt/live/vpn.example.com/privkey.pem

Restart or enable the sstp service:

sudo systemctl daemon-reload
sudo systemctl enable sstp-server
sudo systemctl start sstp-server
sudo systemctl status sstp-server

Step 5 — IP forwarding and NAT

Enable IP forwarding so connected clients can reach the internet through the EC2 instance:

sudo sysctl -w net.ipv4.ip_forward=1

Make it persistent by editing /etc/sysctl.conf and setting net.ipv4.ip_forward=1.

Configure iptables (or nftables) to masquerade outbound traffic:

sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -i ppp+ -o eth0 -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o ppp+ -m state --state RELATED,ESTABLISHED -j ACCEPT

Persist iptables rules using a tool like iptables-persistent:

sudo apt install -y iptables-persistent
sudo netfilter-persistent save

Step 6 — AWS security hardening and logging

Security Group best practices:

  • Restrict SSH (22) to known admin IPs only.
  • Consider restricting TCP 443 to known client IP ranges if possible.
  • Enable VPC Flow Logs for the subnet to monitor traffic patterns.

OS hardening:

  • Apply automatic security updates (e.g., unattended-upgrades).
  • Use fail2ban to protect SSH and other services.
  • Store backups of configuration and keys in a secure location (S3 with encryption).

Step 7 — Configure Windows client

On Windows 10/11:

  • Settings → Network & Internet → VPN → Add a VPN connection.
  • VPN provider: Windows (built-in).
  • Connection name: Your label.
  • Server name or address: vpn.example.com (or Elastic IP).
  • VPN type: Secure Socket Tunneling Protocol (SSTP).
  • Type of sign-in info: Username and password.

After creating the connection, connect and check IP with an external service (e.g., whatismyip) to verify NAT and routing. If you see the EIP of the EC2 instance, NAT is working.

Troubleshooting and diagnostics

Common checks:

  • Service logs: check /var/log/syslog, /var/log/sstp-server.log, and PPP logs.
  • Certificate errors: ensure fullchain (certificate + intermediate) is used; Windows will refuse invalid chains.
  • Connectivity: verify port 443 is reachable from client (telnet/vs curl).
  • MTU issues: if some traffic is unreliable, reduce PPP MTU/MRU (e.g., 1300).
  • IP forwarding: confirm sysctl net.ipv4.ip_forward returns 1 and iptables MASQUERADE is present.

Maintenance, scaling and high availability

Scaling considerations:

  • For larger user bases, choose an instance type with higher CPU and network performance and scale horizontally using AWS Auto Scaling behind a Network Load Balancer (NLB) with TCP passthrough. SSTP uses TLS session affinity; ensure sticky sessions if using multiple backends.
  • Use Amazon Route 53 health checks and failover routing for DNS-based high availability.
  • Consider integrating with LDAP/Active Directory or RADIUS for centralized authentication instead of local chap-secrets.

Certificate renewal in load-balanced setups: centralize cert issuance or use ACM with NLB (note: ACM certs can be used with AWS Load Balancers but not directly with in-VM services unless you terminate TLS at the LB).

Security considerations

Recommendations:

  • Prefer certificate-based client authentication or multi-factor authentication for higher security.
  • Monitor logs for failed authentication attempts and unusual traffic patterns.
  • Rotate service keys and strong shared secrets regularly.
  • Keep the OS and sstp-server packages up-to-date.

Deploying an SSTP VPN on AWS with properly issued TLS certificates gives you a robust, firewall-friendly VPN solution that integrates well with Windows clients and many third-party clients. The approach in this guide emphasizes secure certificate usage, correct network configuration (IP forwarding & NAT), and AWS-specific practices like Elastic IPs and properly scoped Security Groups. For production environments with many users, consider central authentication (RADIUS/LDAP), autoscaling considerations, and terminating TLS at a managed load balancer when appropriate to simplify certificate management.

For additional resources and managed dedicated-IP VPN options, visit Dedicated-IP-VPN at https://dedicated-ip-vpn.com/