WireGuard & VPN Architecture — Protocol Internals, Noise_IK, Kernel vs Userspace, Site-to-Site Routing

Ringkasan

WireGuard adalah protokol VPN modern yang dirancang dengan prinsip minimalis: hanya ~4.000 baris kode vs OpenVPN ~600.000 baris. Keamanannya berasal dari kriptografi modern (Noise_IK, Curve25519, BLAKE2, ChaCha20Poly1305) dan attack surface yang diminimalkan. Catatan ini membahas protocol internals, handshake flow, kernel vs userspace implementation, routing & allowed-ips, multi-hop, serta perbandingan performa dengan OpenVPN/IPsec.

Domain Terkait: networking-fundamentals-tcpip-bgp (fondasi network) → linux-hardening-cis (hardening) → homelab-security-architecture-synthesis (infrastruktur) → dns-fundamentals-bind9 (DNS) → podman-networking-ufw (firewall) → tls-ssl-deepdive (perbandingan crypto)

1. Filosofi Desain WireGuard

WireGuard (Jason A. Donenfeld, 2015-2020) hadir karena frustrasi dengan VPN existing:

Aspek	OpenVPN	IPsec	WireGuard
Kode	~600.000 baris	~400.000 baris	~4.000 baris
Crypto	OpenSSL (ribuan opsi)	Complex IKE	Noise_IK (fixed)
Handshake	TLS + auth	IKEv1/v2 (6-9 msg)	1-RTT (3 msg)
Key rotation	Manual	Complex	Automatic (perfect forward secrecy)
Roaming	❌	❌	✅ Native
Kernel integration	Via tun	Via tun/ipsec	✅ In-kernel (wg)

Prinsip: Setiap opsi adalah attack surface. Tidak ada pilihan cipher, algoritma, atau mode — semuanya fixed.

2. Cryptographic Primitives — Noise_IK

WireGuard menggunakan protokol Noise_IK (Noise Protocol Framework — initiator/pre-known static key). Satu pattern: Noise_IK_25519_ChaChaPoly_BLAKE2s.

Primitive	Fungsi	Alasan
Curve25519	Key exchange (ECDH)	Side-channel resistant, konstanta-time
ChaCha20Poly1305	AEAD encryption	Cepat di CPU tanpa AES-NI
BLAKE2s	Hashing	Hash cepat, built-in keying
HKDF (BLAKE2s)	Key derivation	Extract-expand dari DH result

Mengapa ChaCha20 bukan AES? ChaCha20 adalah ARX cipher (add-rotate-xor) yang tidak butuh hardware AES-NI. Performa konsisten di semua CPU, termasuk ARM dan embedded.

Pre-shared Keys (PSK) Opsional

[Interface]
PrivateKey = base64
ListenPort = 51820
 
[Peer]
PublicKey = base64
PresharedKey = base64  # Opsional — anti-quantum layer
AllowedIPs = 10.0.0.0/24

PSK menambahkan lapisan symmetric encryption di luar Curve25519. Berguna sebagai defense terhadap quantum computer (Grover’s algorithm).

3. Handshake Flow

WireGuard menggunakan 1-RTT handshake (3 messages):

Initiator (Client)            Responder (Server)
      │                              │
      │  Msg 1: Initiation           │
      │  - Static public key (encrypted) │
      │  - Ephemeral public key       │
      │  - Timestamp (anti-replay)    │
      ├─────────────────────────────▶│
      │                              │
      │  Msg 2: Response             │
      │  - Static public key (encrypted) │
      │  - Ephemeral public key       │
      │  - Encrypted empty transport  │
      │◄─────────────────────────────┤
      │                              │
      │  Msg 3: Cookie (if needed)   │
      │  - Anti-DoS cookie           │
      ├─────────────────────────────▶│
      │                              │
      │  ←─── Session established ──→│
      │  Transport key derived       │
      │  (Perfect Forward Secrecy)   │

Key Derivation (KDF Chain)

static_static = DH(init_static, resp_static)      # Long-term auth
ephemeral_remote = DH(init_ephemeral, resp_static) # ECDH
static_remote = DH(init_static, resp_ephemeral)    # ECDH
ephemeral_ephemeral = DH(init_ephemeral, resp_ephemeral) # PFS

# Mix via HKDF chain → session key

Re-keying

Setiap 120 detik atau setelah 2^64 paket, WireGuard melakukan re-handshake otomatis. Ini memberikan Perfect Forward Secrecy: jika kunci jangka panjang bocor, session key tidak bisa di-decrypt.

4. Data Plane Encryption

Setelah handshake, data di-enkripsi dengan ChaCha20Poly1305:

┌─────────────────────────────────────────────┐
│                 WireGuard Packet             │
├────────────┬──────────┬──────────┬───────────┤
│ Type (4B)  │ Reserved │ Session │ Counter   │
│            │ (4B)     │  ID (8B) │ (8B)      │
├────────────┴──────────┴──────────┴───────────┤
│ Encrypted Payload (ChaCha20Poly1305 AEAD)     │
│  - Inner IP packet                           │
│  - Padding (opsional)                        │
├──────────────────────────────────────────────┤
│ Poly1305 MAC tag (16B)                       │
└──────────────────────────────────────────────┘

Counter-based: Setiap packet punya counter monotonic → mencegah replay attack. Counter di-reset saat re-key.

5. Kernel vs Userspace Implementation

Kernel Module (`wg`)

Packet flow: Network → wg module → ChaCha20 (kernel crypto) → tun → userspace
                      ↓
                  Zero-copy di kernel
                      ↓
              Performa ~ linier dengan CPU

Keunggulan:

Latensi lebih rendah (skip context switch)
Throughput lebih tinggi (zero-copy)
Integrasi dengan network stack kernel

Instalasi:

# Kernel module sudah built-in di Linux 5.6+
modprobe wireguard
# Cek
lsmod | grep wireguard

Userspace (`boringtun` — Cloudflare)

Packet flow: Network → tun → userspace (boringtun) → ChaCha20 → userspace lagi

Keunggulan:

Cross-platform (Windows, macOS, BSD)
Update tanpa reboot
Sandboxing lebih mudah
Debug lebih mudah

Perbandingan performa:

Implementasi	Throughput (1Gbps)	Latensi (ms)	CPU Usage
Kernel (wg)	~940 Mbps	0.1-0.3	5-10%
boringtun	~850 Mbps	0.3-0.8	15-25%
OpenVPN (TLS)	~400 Mbps	1-3	30-50%

6. Routing & Allowed-IPs

WireGuard tidak menggunakan routing table tradisional — ia menggunakan AllowedIPs sebagai routing + ACL sekaligus.

[Peer]
PublicKey = peer1_publickey
AllowedIPs = 10.0.0.2/32, 192.168.1.0/24

Bagaimana AllowedIPs Bekerja

Terima: Packet dengan src IP dalam AllowedIPs diterima
Kirim: Packet dengan dst IP dalam AllowedIPs dikirim ke peer ini
Route otomatis: WireGuard menambahkan route ke table kernel

# Cek route yang dibuat WireGuard
ip route show dev wg0
# Output: 10.0.0.0/24 dev wg0 proto kernel scope link src 10.0.0.1

Full Tunnel vs Split Tunnel

# Full tunnel — semua traffic via VPN
AllowedIPs = 0.0.0.0/0, ::/0
 
# Split tunnel — hanya subnet tertentu
AllowedIPs = 10.0.0.0/8, 172.16.0.0/12

7. Multi-Hop & Site-to-Site

Multi-Hop (Bounce)

Client ⇄ Relay (VPS) ⇄ Office

Konfigurasi relay:

[Interface]
Address = 10.0.0.1/24
ListenPort = 51820
PrivateKey = relay_private
 
[Peer]
# Client
PublicKey = client_public
AllowedIPs = 10.0.0.2/32
 
[Peer]
# Office
PublicKey = office_public
AllowedIPs = 10.0.0.3/32, 192.168.1.0/24

Relay harus enable IP forwarding:

sysctl -w net.ipv4.ip_forward=1
sysctl -w net.ipv6.conf.all.forwarding=1

Site-to-Site

Site A (10.0.0.0/24) ⇄ VPS ⇄ Site B (10.0.1.0/24)

# Site A
[Peer]
PublicKey = site_b_public
AllowedIPs = 10.0.1.0/24, 10.0.0.0/24
Endpoint = site-b.example.com:51820

8. NAT Traversal & Roaming

Native Roaming

WireGuard mendeteksi perubahan source IP/port setiap kali packet diterima. Jika client pindah jaringan (WiFi → 4G), WireGuard tetap connect tanpa handshake ulang.

Client @ IP A ────▶ Server
     │
     │ (pindah WiFi)
     ▼
Client @ IP B ────▶ Server
     │               │
     │ Packet tiba   │ Server update endpoint
     │ dari IP baru  │ di memory
     ◀───────────────┤

Persistent Keepalive

Untuk NAT/firewall yang timeout:

[Peer]
PersistentKeepalive = 25  # detik

Nilai umum: 25 detik. Jangan terlalu kecil (< 10) — bisa dianggap DoS.

9. Performance Benchmark

VPN	1-Core Throughput	4-Core Throughput	Latency Add	CPU/Connection
WireGuard	940 Mbps	3.8 Gbps	+0.1 ms	1% / 1K conn
IPsec (AES-NI)	800 Mbps	3.2 Gbps	+0.3 ms	3% / 1K conn
OpenVPN (AES-256)	300 Mbps	800 Mbps	+1.5 ms	8% / 1K conn
OpenVPN (ChaCha20)	250 Mbps	700 Mbps	+2.0 ms	10% / 1K conn

WireGuard 3-10× lebih cepat dari OpenVPN untuk throughput tinggi.

10. MTU/MSS Considerations

WireGuard menambahkan 60-byte overhead per packet. Jika interface MTU = 1500:

Payload max = 1500 - 60 = 1440 bytes

Konfigurasi:

[Interface]
Address = 10.0.0.1/24
MTU = 1420  # Untuk ethernet tunnel

MTU calculator:

$MTU_{t u nn e l} = MTU_{l ink} - 80 (IPv6) atau - 60 (IPv4)$

Recomendasi tabel:

Link Type	MTU
Ethernet (1500)	1420
PPPoE (1492)	1412
4G/LTE (1500)	1420
IPv6 tunnel	1400
GRE tunnel	1360

11. Deploy Guide

Server

# Install
dnf install wireguard-tools  # Fedora
# atau
apt install wireguard         # Ubuntu
 
# Generate keys
wg genkey | tee /etc/wireguard/private.key | wg pubkey > /etc/wireguard/public.key
chmod 600 /etc/wireguard/private.key
 
# Config /etc/wireguard/wg0.conf

[Interface]
Address = 10.0.0.1/24
ListenPort = 51820
PrivateKey = <server-private>
PostUp = iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i wg0 -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
 
[Peer]
PublicKey = <client-public>
AllowedIPs = 10.0.0.2/32

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

Client

[Interface]
PrivateKey = <client-private>
Address = 10.0.0.2/24
DNS = 1.1.1.1
 
[Peer]
PublicKey = <server-public>
Endpoint = server.example.com:51820
AllowedIPs = 0.0.0.0/0, ::/0  # Full tunnel
PersistentKeepalive = 25

12. Keamanan & Auditing

Audit Checklist

PrivateKey file mode 600
ListenPort tidak exposed ke publik (pakai firewall)
AllowedIPs serumit mungkin — tidak 0.0.0.0/0 kecuali perlu
Rotate keys periodik (setiap 6 bulan)
PresharedKey enabled untuk sensitive link
Firewall: hanya port 51820/UDP dari peer yang dikenal

Firewall Config

# UFW
ufw allow in on eth0 to any port 51820 proto udp
 
# nftables
nft add rule inet filter input udp dport 51820 accept
nft add rule inet filter input iifname "wg0" accept
nft add rule inet filter forward iifname "wg0" oifname "eth0" accept

13. Referensi

WireGuard Whitepaper: https://www.wireguard.com/papers/wireguard.pdf
Noise Protocol Framework: https://noiseprotocol.org/noise.html
boringtun (Cloudflare): https://github.com/cloudflare/boringtun
WireGuard Official: https://www.wireguard.com/
Performance Benchmark: https://www.wireguard.com/performance/

Cross-link vault:

networking-fundamentals-tcpip-bgp — routing & network dasar
linux-hardening-cis — OS hardening
homelab-security-architecture-synthesis — infrastruktur
dns-fundamentals-bind9 — DNS integration
podman-networking-ufw — firewall konfigurasi
tls-ssl-deepdive — crypto fundamental
cryptography-biometrics — kriptografi

Azhar's Notes

Navigation

WireGuard & VPN Architecture — Protocol Internals, Noise_IK, Kernel vs Userspace, Site-to-Site Routing

Daftar Isi

1. Filosofi Desain WireGuard

2. Cryptographic Primitives — Noise_IK

Pre-shared Keys (PSK) Opsional

3. Handshake Flow

Key Derivation (KDF Chain)

Re-keying

4. Data Plane Encryption

5. Kernel vs Userspace Implementation

Kernel Module (`wg`)

Userspace (`boringtun` — Cloudflare)

6. Routing & Allowed-IPs

Bagaimana AllowedIPs Bekerja

Full Tunnel vs Split Tunnel

7. Multi-Hop & Site-to-Site

Multi-Hop (Bounce)

Site-to-Site

8. NAT Traversal & Roaming

Native Roaming

Persistent Keepalive

9. Performance Benchmark

10. MTU/MSS Considerations

11. Deploy Guide

Server

Client

12. Keamanan & Auditing

Audit Checklist

Firewall Config

13. Referensi

Tampilan Grafik

Daftar Isi

Azhar's Notes

Navigation

WireGuard & VPN Architecture — Protocol Internals, Noise_IK, Kernel vs Userspace, Site-to-Site Routing

Daftar Isi

1. Filosofi Desain WireGuard

2. Cryptographic Primitives — Noise_IK

Pre-shared Keys (PSK) Opsional

3. Handshake Flow

Key Derivation (KDF Chain)

Re-keying

4. Data Plane Encryption

5. Kernel vs Userspace Implementation

Kernel Module (wg)

Userspace (boringtun — Cloudflare)

6. Routing & Allowed-IPs

Bagaimana AllowedIPs Bekerja

Full Tunnel vs Split Tunnel

7. Multi-Hop & Site-to-Site

Multi-Hop (Bounce)

Site-to-Site

8. NAT Traversal & Roaming

Native Roaming

Persistent Keepalive

9. Performance Benchmark

10. MTU/MSS Considerations

11. Deploy Guide

Server

Client

12. Keamanan & Auditing

Audit Checklist

Firewall Config

13. Referensi

Tampilan Grafik

Daftar Isi

Kernel Module (`wg`)

Userspace (`boringtun` — Cloudflare)