The cardinal rule: the gateway must never become an open relay. A misconfigured egress box is an anonymous proxy with your name on the bill — and your allowlisted IP on someone else's abuse.

• Authentication is WireGuard keys. There are no passwords. Each developer gets a unique keypair and a unique preshared key (post-quantum-hardening, and revocation stays per-person).
• No open ports except SSH and WireGuard. The nftables ruleset drops all other inbound traffic. The Terraform security group additionally restricts SSH to your admin CIDR at the AWS layer.
• Forwarding is one-way by design. The forward chain only allows wg0 → internet and established return traffic. Internet hosts cannot initiate connections through the box, and peers cannot reach each other (no lateral movement between developer laptops).
• No HTTP proxy ports. This project deliberately uses a VPN rather than Squid/Tinyproxy: there is no proxy port to accidentally leave open, and it works with every language and HTTP client without proxy-agent code.

• One config per human. Never share a .conf between developers — you lose the ability to revoke individually. Configs contain private keys; treat them like SSH keys (delete the temporary copy in the home directory after importing).
• Revoke on departure. sudo ./remove-peer.sh <name> disconnects immediately.
• Audit who's connected. sudo ./list-peers.sh shows last handshakes; sudo wg show gives live transfer counts. Connection metadata only — the gateway never sees plaintext API payloads (TLS terminates at the vendor).
• Keep API credentials off the gateway. The box routes packets; your vendor API keys belong in your local backend's environment, not here.
• Patch it. It's one package doing one job, but it's still a public box: apt upgrade periodically, or enable unattended-upgrades.

• A compromised developer laptop can obviously send traffic through the gateway — same as any VPN.
• The vendor sees one IP for all developers. If you need per-developer attribution at the vendor, you need multiple gateways/EIPs.
• IPv6: the gateway is IPv4-only. Full-tunnel configs route ::/0 into the tunnel where it's dropped (preventing IPv6 leaks), but split-tunnel peers talking to an IPv6-capable vendor could bypass the tunnel via IPv6 — pin the vendor's IPv4 addresses or use full tunnel.