What Is SOCKS4? Protocol Explained

What Is SOCKS4?

SOCKS4 is a network proxy protocol that routes TCP traffic between a client and a destination server through an intermediary. It operates at the session layer (Layer 5) of the OSI model, making it protocol-agnostic for any TCP-based application.

How SOCKS4 Works

When a client connects through a SOCKS4 proxy, it sends a connection request containing the destination IP address and port number. The proxy establishes the TCP connection on the client's behalf and relays data in both directions. Unlike HTTP proxies, SOCKS4 does not interpret the traffic itself — it simply forwards raw bytes.

SOCKS4 vs SOCKS5: Key Differences

SOCKS4 has several limitations compared to its successor, SOCKS5:

• No UDP support — SOCKS4 handles TCP connections only. SOCKS5 adds UDP relay capabilities for streaming and DNS lookups.
• No authentication — SOCKS4 offers no built-in username/password authentication. SOCKS5 supports multiple authentication methods.
• No IPv6 — SOCKS4 only works with IPv4 addresses. SOCKS5 supports both IPv4 and IPv6.
• No domain resolution — SOCKS4 requires the client to resolve DNS locally. SOCKS4a added remote DNS, but SOCKS5 handles this natively.

When to Use SOCKS4

SOCKS4 proxies remain useful for simple TCP-only tasks where authentication is unnecessary. They are often faster due to lower protocol overhead. You can verify SOCKS4 proxy functionality using our Proxy Checker tool or browse available proxies on ipproxy.site.

For most modern use cases, however, SOCKS5 is recommended due to its broader feature set.