Wireguard Vpn

When to use

Use when you need a kernel-level mesh VPN between two or more Linux hosts and the kernel module is available (Linux ≥ 5.6 ships wireguard.ko in the mainline kernel). WireGuard is the right answer when you want:

• UDP-based tunnels with sub-millisecond overhead per packet.
• Modern cryptography only (Curve25519 for key exchange, ChaCha20 for symmetric, Poly1305 for MAC). No cipher negotiation, no downgrade surface.
• A configuration that fits in one file and can be diffed in version control.

It is the wrong answer when you need a managed SaaS connector, when the hosts run operating systems without the kernel module, or when the firewall at the perimeter blocks UDP outright — WireGuard does not fall back to TCP.

Examples

A minimal server-side /etc/wireguard/wg0.conf:

[Interface]
Address = 10.0.0.1/24
ListenPort = 51820
PrivateKey = <server-private-key-base64>
# Replace with your firewall rule before bringing the interface up
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-key-base64>
AllowedIPs = 10.0.0.2/32

The corresponding client config:

[Interface]
Address = 10.0.0.2/24
PrivateKey = <client-private-key-base64>

[Peer]
PublicKey = <server-public-key-base64>
Endpoint = vpn.example.com:51820
AllowedIPs = 10.0.0.0/24
PersistentKeepalive = 25

Bringing the interface up and confirming the handshake:

sudo wg-quick up wg0
sudo wg show
# expected: latest handshake within the last 2 minutes, transfer counters climbing

For example, generating keys with the wg utility:

wg genkey | tee privatekey | wg pubkey > publickey

Pitfalls to avoid

• Do not commit the PrivateKey to a public repo; it is the long-term identity for the interface and revoking it requires redistributing a new key to every peer.
• Do not forget to open UDP 51820 (or your chosen port) on the cloud provider's security group; the kernel module loads fine without it, but no handshake ever arrives.
• Do not set AllowedIPs = 0.0.0.0/0 on the client unless you intend the tunnel to be the default route; a misconfigured server AllowedIPs silently black-holes the client's traffic.
• Do not run WireGuard over TCP wrappers like tcp_tunnel; the kernel module speaks UDP only, and any TCP fallback you build is a separate application that does not benefit from the kernel fast path.
• Do not skip PersistentKeepalive on peers behind a NAT; without it the NAT mapping expires and the next inbound handshake fails silently.