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Thu, 12 Mar 2026 18:25:53 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-man@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Fri, 13 Mar 2026 00:25:53 +0200 From: "Ran Benita" To: "Alejandro Colomar" Cc: linux-man@vger.kernel.org Message-Id: <18e37f7f-21e9-4e8d-bef3-2adde5980bc2@app.fastmail.com> Subject: man/man7/tcp.7: Document effect of TCP_DEFER_ACCEPT on clientsocket Content-Type: text/plain Content-Transfer-Encoding: 7bit TCP_DEFER_ACCEPT has an interesting little-known effect on client sockets. I don't think it's very useful but should still be documented. See here for reference: Signed-off-by: Ran Benita --- man/man7/tcp.7 | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/man/man7/tcp.7 b/man/man7/tcp.7 index adfd6623e..85f6c631c 100644 --- a/man/man7/tcp.7 +++ b/man/man7/tcp.7 @@ -1091,6 +1091,11 @@ Allow a listener to be awakened only when data arrives on the socket. Takes an integer value (seconds), this can bound the maximum number of attempts TCP will make to complete the connection. +.IP +On a client socket, if non-zero, delays sending the final ACK of the three-way +handshake until the socket has data to send, in which case the ACK is +piggybacked on the first data segment, or a delayed-ACK timeout is reached. +.IP This option should not be used in code intended to be portable. .TP .BR TCP_INFO " (since Linux 2.4)" -- 2.53.0