Protocols & authentication · glossary

UDP and proxies

UDP proxying is the relay of connectionless datagrams through a proxy, which SOCKS5 defines with the UDP ASSOCIATE command but which most commercial proxy networks do not support. HTTP proxies are TCP by nature, and residential and mobile gateways relay TCP streams only. Applications that insist on UDP, including HTTP/3 over QUIC, DNS over UDP and most VoIP or gaming protocols, fall back to TCP or bypass the proxy.

1 min read Also called SOCKS5 UDP ASSOCIATE, QUIC through proxies Updated

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Practical consequences#

  • Browsers: disable QUIC or accept that HTTP/3 will not be used through the proxy; sites fall back to HTTP/2 over TCP automatically.
  • DNS: resolve through the proxy (remote DNS) rather than sending UDP queries locally.
  • Streaming and calls: use a VPN-type service; a proxy is the wrong tool.

Why providers skip UDP#

Datagrams cannot be attributed to a session or metered as easily, they are the vector of amplification attacks, and household NATs handle them inconsistently. The cost of supporting them outweighs the demand for web work.

How it works at ProxShift#

ProxShift gateways and dedicated addresses are TCP only: no UDP ASSOCIATE, no BIND, no QUIC. Every HTTP client falls back to HTTP/2 or HTTP/1.1 through the proxy.

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