From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6994C4361B for ; Fri, 11 Dec 2020 20:34:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 718AD2404C for ; Fri, 11 Dec 2020 20:34:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436714AbgLKStp (ORCPT ); Fri, 11 Dec 2020 13:49:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56356 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436570AbgLKStD (ORCPT ); Fri, 11 Dec 2020 13:49:03 -0500 Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23FB3C0613D3 for ; Fri, 11 Dec 2020 10:48:21 -0800 (PST) Received: by mail-wr1-x442.google.com with SMTP id r3so10079820wrt.2 for ; Fri, 11 Dec 2020 10:48:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=1BjPXRRx0YYXjEaZ9JagSV2seEZPq6wpByXZm2AVE0s=; b=ONzQDNV9njxqD/HutP7dA5whLU4qkq0GtHD2BSeWhWQelvUtPwuqR7WTkcEMRSh8hl PSk/org+G0s2hfLRp9IpjRuC9NBHtwG/t7YE9LMGleiWOhfgQCQA2KYWB91YFtspxOjG bKQBEfkBO65qTcv/Y7J2bVhIxZhyw37mUxb6UvASm3OUymR4M+xHfCQVuGisr3muxNR7 j108Dtu/u7eQfcJxJCV/WZsOsjMx4hmWgRxeOAKFw9NxArW/1N1GUQGDWxKFuC/FK4Ly ZJn2ZabSudfU2m2bgJKS5vLDBXBjrZECDRgo02uusRfDlZyPh8WEr9lNDBGTeGgPUX5t 7AQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=1BjPXRRx0YYXjEaZ9JagSV2seEZPq6wpByXZm2AVE0s=; b=WRIPje13Udx6hm4oS5k8wxkrcB7ZZBeZ5ed/kwcWC6KY0847IP5oDejy62JIpffeOn TcoA5ObcP5wVkp6W8pIKwW/ume/8Qqo53Vl1Fl0abF4s8ya+uFtt3JPp73t9VSLqk+PT 5G4lfXXYPoS35Br7V95X5mFs5w+FN5QlDPc8Fll8UtX4/85KzVqlq69RmUkNcjWLwRT4 3h31blyBkJZrii+cxCdrCa6dBuliS3mTdCsw45nkz3iIsx8x51tMutHVZkrEgX4ryTED GP97qshZ8kZYUSqQybd3pkHCsUsskV8PgLCvoYzlRjIULg+twOkEzEjiAF6U9Ld/3Wcc XswA== X-Gm-Message-State: AOAM531+2rc8PFhhOVltCLSfUXzsr6Op5YwJlBdetQrl9NrmGM0viFGT VdD7fHhMr/uT9Fzz6jQ8tRU= X-Google-Smtp-Source: ABdhPJxk2vLjKt1bhwmSFgdC4TqMfR1LYzzVMdkJlB20KjRmaweg7t/P2xLghXdOnqToYJLAT7zoXA== X-Received: by 2002:a5d:618c:: with SMTP id j12mr15373620wru.182.1607712499952; Fri, 11 Dec 2020 10:48:19 -0800 (PST) Received: from debian.vlc ([170.253.51.130]) by smtp.gmail.com with ESMTPSA id l1sm16193079wmi.15.2020.12.11.10.48.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Dec 2020 10:48:19 -0800 (PST) From: Alejandro Colomar To: mtk.manpages@gmail.com Cc: Alejandro Colomar , linux-man@vger.kernel.org, Philip Rowlands , Eric Dumazet , Hannes Frederic Sowa , "David S . Miller" Subject: [PATCH v2] tcp.7: tcp_syncookies: It is now an integer [0, 2] Date: Fri, 11 Dec 2020 19:47:10 +0100 Message-Id: <20201211184709.38128-1-alx.manpages@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <086c4c44-0443-9e13-0087-fb8c2adcb80e@gmail.com> References: <086c4c44-0443-9e13-0087-fb8c2adcb80e@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org Since Linux kernel 3.12, tcp_syncookies can have the value 2, which sends out cookies unconditionally. Related kernel commits: 5ad37d5deee1ff7150a2d0602370101de158ad86 d8513df2598e5142f8a5c4724f28411936e1dfc7 Reported-by: Philip Rowlands Signed-off-by: Alejandro Colomar Cc: Eric Dumazet Cc: Hannes Frederic Sowa Cc: David S. Miller --- man7/tcp.7 | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/man7/tcp.7 b/man7/tcp.7 index d983a8f9a..cce8dd910 100644 --- a/man7/tcp.7 +++ b/man7/tcp.7 @@ -830,12 +830,11 @@ The maximum number of times a SYN/ACK segment for a passive TCP connection will be retransmitted. This number should not be higher than 255. .TP -.IR tcp_syncookies " (Boolean; since Linux 2.2)" +.IR tcp_syncookies " (integer; default: 1; since Linux 2.2)" .\" Since 2.1.43 Enable TCP syncookies. The kernel must be compiled with .BR CONFIG_SYN_COOKIES . -Send out syncookies when the syn backlog queue of a socket overflows. The syncookies feature attempts to protect a socket from a SYN flood attack. This should be used as a last resort, if at all. @@ -849,6 +848,18 @@ For recommended alternatives see .IR tcp_synack_retries , and .IR tcp_abort_on_overflow . +Set to one of the following values: +.RS +.IP 0 3 +Disable TCP syncookies. +.IP 1 +Send out syncookies when the syn backlog queue of a socket overflows. +.IP 2 +(since Linux 3.12) +.\" commit 5ad37d5deee1ff7150a2d0602370101de158ad86 +Send out syncookies unconditionally. +This can be useful for network testing. +.RE .TP .IR tcp_timestamps " (integer; default: 1; since Linux 2.2)" .\" Since 2.1.36 -- 2.29.2