Port 51820/UDP (WireGuard) - Vulnerabilities, CVEs, Security Guide

Service Description

Port 51820 (UDP) is the commonly used, though not exclusively required, port for WireGuard, a modern and secure VPN protocol. WireGuard aims to be simpler, faster, and more secure than older VPN technologies like IPsec and OpenVPN. It operates primarily at Layer 3, encapsulating IP packets within UDP packets. The protocol is designed with strong cryptographic primitives and a small codebase, reducing the attack surface and making auditing easier. It uses Curve25519 for key exchange, ChaCha20 for symmetric encryption, Poly1305 for message authentication, and BLAKE2s for hashing. WireGuard connections are established through a handshake process involving public keys, pre-shared keys (optional), and cryptographic nonces to ensure authenticity and prevent replay attacks. The protocol is designed for both client-to-server (road warrior) and site-to-site VPN configurations.

## Firewall Recommendations

If you are running a WireGuard server, it is essential to allow inbound UDP traffic on port 51820 (or the configured port) only from trusted IP addresses or networks. Block all other inbound traffic to this port. For clients, outbound UDP traffic to the WireGuard server's IP address and port must be allowed. It is crucial to implement proper firewall rules to restrict access to the WireGuard server and the internal network it protects. Regularly review and update firewall rules to ensure they are still appropriate. Consider using a dedicated firewall device or software firewall with intrusion detection and prevention capabilities to monitor traffic and detect suspicious activity related to WireGuard. Additionally, ensure that the WireGuard software and operating system are kept up-to-date with the latest security patches to mitigate any known vulnerabilities.

Security Information

While WireGuard itself is designed with security in mind, misconfigurations can lead to vulnerabilities. A primary risk is exposing the WireGuard interface directly to the internet without proper firewall rules, potentially allowing unauthorized access to the VPN server or the internal network it protects. Another risk involves improper key management, such as using weak or compromised keys. Replay attacks are mitigated by the protocol's design, but incorrect nonce handling or implementation flaws in specific software using WireGuard could create vulnerabilities. Because WireGuard often provides access to internal networks, it is a valuable target for attackers seeking to gain access to those resources after an initial compromise. Furthermore, denial-of-service (DoS) attacks targeting the WireGuard server are possible, potentially disrupting VPN connectivity.

Port 51820 (WireGuard)

Quick Info

Service Description

Security Information

Common Software

Find devices with this port

Related Ports

Find all devices with port 51820 open