DOC: proxy-protocol: clarify UDP usage

the proxy protocol spec didn't specify UDP and therefore most
implementations treat it as a TCP connection and re-use the last send
information for a ip/port pair.

This change makes it more clear.
This commit is contained in:
Kevin Ludwig 2026-05-13 16:53:58 +02:00 committed by Willy Tarreau
parent f4edcdf4de
commit 6e9b9196bd

View File

@ -1,4 +1,4 @@
2020/03/05 Willy Tarreau
2026/04/27 Willy Tarreau
HAProxy Technologies
The PROXY protocol
Versions 1 & 2
@ -31,6 +31,7 @@ Revision history
2025/09/09 - added SSL-related TLVs for key exchange group and signature
scheme (Steven Collison)
2026/01/15 - added SSL client certificate TLV (Simon Ser)
2026/04/27 - clarified UDP usage (Valaphee)
1. Background
@ -175,6 +176,11 @@ The receiver may apply a short timeout and decide to abort the connection if
the protocol header is not seen within a few seconds (at least 3 seconds to
cover a TCP retransmit).
For UDP, the PROXY protocol header and the proxied UDP payload MUST be sent in
the same datagram. The sender MUST NOT split the PROXY protocol header across
multiple UDP datagrams, and the receiver MUST parse the header independently
for each received datagram.
The receiver MUST be configured to only receive the protocol described in this
specification and MUST not try to guess whether the protocol header is present
or not. This means that the protocol explicitly prevents port sharing between