Glossary · Protocols & authentication
SOCKS4 proxy
An older version of the SOCKS protocol that relays TCP traffic but lacks authentication, UDP support and remote DNS.
SOCKS4 is the predecessor to SOCKS5, and the comparison is the clearest way to understand it. It relays TCP connections without inspecting them, which is the core SOCKS idea, but it stops there: no built-in authentication, no UDP, and no remote DNS resolution.
Those absences are why it is largely legacy. Without authentication a SOCKS4 proxy is harder to secure; without UDP it cannot carry real-time or DNS traffic; without remote DNS it is prone to the very leaks SOCKS5 was extended to prevent.
You will still meet SOCKS4 in older tooling and public proxy lists, and for plain TCP relaying it works. But when a choice exists, SOCKS5 is the version that closes the gaps.
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