Deploying a robust IKEv2 VPN on AWS gives you the flexibility, control, and privacy of a self-hosted solution while leveraging AWS’s scalable infrastructure. This guide walks you through a secure, production-ready deployment using an EC2 instance running strongSwan (a widely used IKEv2/IPsec implementation). The steps below cover VPC and security configuration, certificate generation, strongSwan configuration for both certificate-based and EAP authentication, firewall and NAT setup, client configuration notes, and troubleshooting tips.

Why IKEv2 on AWS?

IKEv2 is preferred in modern VPN deployments because it supports fast rekeying, Mobility and Multihoming Protocol (MOBIKE) for seamless roaming, robust cryptographic suites (IKEv2 + IPsec), and native client support across major platforms. Hosting on AWS provides predictable performance, Elastic IPs for stable endpoints, and the ability to scale the underlying compute resources as needed.

High-level architecture

  • VPC with a public subnet and route to an Internet Gateway.
  • EC2 instance (Ubuntu LTS or Amazon Linux 2) with an Elastic IP assigned.
  • Security Group allowing UDP 500 and 4500 and ESP (IP protocol 50) from trusted clients.
  • strongSwan on EC2, configured for IKEv2 with either certificate-based authentication or EAP(MSCHAPv2).
  • IP forwarding + NAT (MASQUERADE) to allow VPN clients to reach the Internet through the EC2 instance.

Prerequisites

  • AWS account and permissions to create VPCs, EC2 instances, Elastic IPs, Security Groups, and Internet Gateways.
  • Basic Linux command line skills and familiarity with OpenSSL/PKI concepts.
  • Recommended instance: t3.small or larger (depending on expected throughput), with a public IP (Elastic IP recommended).

Step 1 — Network and EC2 setup

1. Create or choose a VPC and a public subnet. Attach an Internet Gateway and ensure the subnet’s route table routes 0.0.0.0/0 to the IGW.

2. Launch an EC2 instance in the public subnet. Choose Ubuntu 22.04 LTS or Amazon Linux 2. Assign an Elastic IP (EIP) to the instance so the server keeps the same public IP if stopped/started.

3. Create a Security Group for the VPN instance with the following inbound rules:

  • UDP 500 (IKE)
  • UDP 4500 (NAT-T)
  • Protocol 50 (ESP) — AWS Security Groups do not support ESP directly; to allow ESP, ensure no Network ACL blocks protocol 50. For Security Group, allow all traffic from trusted client IPs or allow all outbound and specific inbound UDP ports. Use NACLs carefully.
  • SSH (TCP 22) from your admin IP only

Step 2 — Install strongSwan and dependencies

SSH into the instance and install strongSwan. On Ubuntu:

sudo apt update && sudo apt install -y strongswan strongswan-pki libcharon-extra-plugins

On Amazon Linux 2:

sudo yum install -y epel-release && sudo yum install -y strongswan

The libcharon-extra-plugins package provides several authentication and EAP plugins.

Step 3 — PKI: Build a CA and server/client certificates

Using strongSwan’s pki tool simplifies certificate creation. Below are condensed commands for a CA, a server cert, and a client cert (certificate-based authentication). Adjust names and lifetimes as needed.

Generate a CA key and cert:

sudo mkdir -p /etc/swanpki && cd /etc/swanpki

sudo ipsec pki --gen --type rsa --size 4096 --outform pem > caKey.pem

sudo ipsec pki --self --ca --lifetime 3650 --in caKey.pem --type rsa --dn "CN=IKEv2-CA" --outform pem > caCert.pem

Generate server key and CSR, then sign with CA:

sudo ipsec pki --gen --type rsa --size 4096 --outform pem > serverKey.pem

sudo ipsec pki --pub --in serverKey.pem --type rsa | sudo ipsec pki --issue --lifetime 1825 --cacert caCert.pem --cakey caKey.pem --dn "CN=server.example.com" --san="server.example.com" --outform pem > serverCert.pem

Copy serverKey.pem and serverCert.pem to /etc/ipsec.d/private and /etc/ipsec.d/certs respectively, and caCert.pem to /etc/ipsec.d/cacerts.

sudo cp serverKey.pem /etc/ipsec.d/private/serverKey.pem

sudo cp serverCert.pem /etc/ipsec.d/certs/serverCert.pem

sudo cp caCert.pem /etc/ipsec.d/cacerts/caCert.pem

Client certificates

For certificate-based clients, generate a key and certificate, then export to .p12 for use on Windows/macOS:

sudo ipsec pki --gen --type rsa --size 4096 --outform pem > clientKey.pem

sudo ipsec pki --pub --in clientKey.pem --type rsa | sudo ipsec pki --issue --lifetime 1825 --cacert caCert.pem --cakey caKey.pem --dn "CN=client@example.com" --outform pem > clientCert.pem

Export to PKCS#12:

openssl pkcs12 -export -inkey clientKey.pem -in clientCert.pem -name "client" -certfile caCert.pem -out client.p12

Step 4 — strongSwan server configuration

You can use ipsec.conf/ipsec.secrets (classic) or swanctl.conf (recommended for newer strongSwan). Here’s a sample minimal ipsec.conf for IKEv2 using certificate-based authentication:

sudo tee /etc/ipsec.conf > /dev/null <<'EOF'
config setup
charondebug="ike 1, knl 1, cfg 0"

conn ikev2-vpn
auto=add
compress=no
type=tunnel
keyexchange=ikev2
fragmentation=yes
forceencaps=yes
dpdaction=clear
dpddelay=300s
rekey=no
left=%any
leftcert=serverCert.pem
leftsendcert=always
leftid=@server.example.com
leftsubnet=0.0.0.0/0
right=%any
rightid=%any
rightauth=eap-mschapv2
rightsourceip=10.10.10.0/24
rightsendcert=never
eap_identity=%identity
EOF

For EAP (username/password) replace serverCert usage by keeping leftcert for server and set rightauth=eap-mschapv2. Define users in /etc/ipsec.secrets:

sudo tee -a /etc/ipsec.secrets > /dev/null <<'EOF'
: RSA "serverKey.pem"
username : EAP "StrongPasswordHere"
EOF

For certificate authentication, clients present their certs; for EAP, clients use username/password and server uses server certificate.

Step 5 — Kernel networking and NAT

Enable IP forwarding:

sudo sysctl -w net.ipv4.ip_forward=1

Persist it under /etc/sysctl.conf:

sudo sed -i '/net.ipv4.ip_forward/d' /etc/sysctl.conf && echo 'net.ipv4.ip_forward=1' | sudo tee -a /etc/sysctl.conf

Configure NAT so VPN clients can access the Internet through the EC2 public IP. Using iptables (classic example):

sudo iptables -t nat -A POSTROUTING -s 10.10.10.0/24 -o eth0 -j MASQUERADE

Save the iptables rules (Ubuntu):

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

Step 6 — Start and test strongSwan

Start or restart strongSwan:

sudo systemctl enable strongswan

sudo systemctl restart strongswan

Check status and logs:

sudo ipsec statusall

sudo journalctl -u strongswan -f

On the client, import the CA certificate (for cert validation) and either import the client .p12 or configure username/password. Connect using the server Elastic IP or DNS name which matches the server certificate’s CN or SAN.

Client configuration notes

  • Windows 10/11: Use the built-in IKEv2; for EAP-MSCHAPv2 use the user credentials. For certificate authentication import the .p12 and select certificate on the VPN connection.
  • macOS/iOS: Native IKEv2 support; import CA and client certificates, then add a new IKEv2 connection in System Preferences (macOS) or Settings → General → VPN (iOS).
  • Linux: strongSwan’s swanctl or NetworkManager’s strongSwan plugin can be used; for the command line, use ipsec up ikev2-vpn after proper config.
  • Split tunneling vs full tunnel: Configure leftsubnet/rightsubnet appropriately. The sample above uses a full tunnel for clients (0.0.0.0/0). Use route-based rules or client OS settings for split routing.

Security hardening and best practices

  • Use strong ciphers (AES-GCM, CHACHA20-POLY1305, SHA-2) and prefer modern IKEv2 proposals. Configure ike and esp proposals explicitly in ipsec.conf or swanctl.conf.
  • Limit Security Group inbound sources to expected client IP ranges when possible.
  • Enable logging with a reasonable level for debugging, but avoid verbose logs in production that may include sensitive data.
  • Rotate server and client certificates periodically and maintain a CRL or OCSP if revocation is required.
  • Use AWS monitoring (CloudWatch) and VPC Flow Logs to observe traffic patterns and detect anomalies.

Troubleshooting

If a client fails to connect, check the following in order:

  • Security Group and NACL settings — ensure UDP 500/4500 are allowed and NACLs do not block ESP or UDP replies.
  • strongSwan logs: sudo journalctl -u strongswan -e or ipsec statusall.
  • Confirm server certificates are in the correct /etc/ipsec.d/ locations and file permissions allow strongSwan to read them.
  • Use tcpdump to inspect packets (watch for IKE exchanges and NAT-T traffic): sudo tcpdump -n -i any port 500 or port 4500 or proto 50.
  • Check IP forwarding and iptables NAT rules are applied. Use sudo iptables -t nat -L -n -v to list NAT rules.

Scaling and availability considerations

For higher availability or to support many clients, consider:

  • Using an Auto Scaling Group with a shared backend for client state (IKEv2 tends to be stateful, so a single instance may be simpler for small deployments).
  • Fronting strongSwan with AWS Network Load Balancer (NLB) for UDP 500/4500. Note: handling ESP (protocol 50) across multiple instances is non-trivial because ESP is stateful. Many setups rely on a single gateway or route clients to specific endpoints via DNS or different EIPs.
  • Monitoring instance CPU, network throughput, and scaling instance type as needed.

With these steps you’ll have a secure IKEv2 VPN endpoint running on AWS. The combination of strongSwan and AWS components gives you a flexible, auditable, and performant VPN service suitable for developers, site administrators, and enterprise remote access.

For additional resources and step-by-step downloadable configs, visit Dedicated-IP-VPN at https://dedicated-ip-vpn.com/.