46 lines
1.9 KiB
Diff
46 lines
1.9 KiB
Diff
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From 559357d267197602d591a8a075146ab35146dbc6 Mon Sep 17 00:00:00 2001
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From: Simon Kelley <simon@thekelleys.org.uk>
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Date: Tue, 7 Mar 2023 22:07:46 +0000
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Subject: [PATCH] Set the default maximum DNS UDP packet size to 1232.
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http://www.dnsflagday.net/2020/ refers.
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Thanks to Xiang Li for the prompt.
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(cherry picked from commit eb92fb32b746f2104b0f370b5b295bb8dd4bd5e5)
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---
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man/dnsmasq.8 | 3 ++-
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src/config.h | 2 +-
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2 files changed, 3 insertions(+), 2 deletions(-)
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diff --git a/man/dnsmasq.8 b/man/dnsmasq.8
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index 9dd5430..8956f6d 100644
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--- a/man/dnsmasq.8
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+++ b/man/dnsmasq.8
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@@ -183,7 +183,8 @@ to zero completely disables DNS function, leaving only DHCP and/or TFTP.
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.TP
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.B \-P, --edns-packet-max=<size>
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Specify the largest EDNS.0 UDP packet which is supported by the DNS
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-forwarder. Defaults to 4096, which is the RFC5625-recommended size.
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+forwarder. Defaults to 1232, which is the recommended size following the
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+DNS flag day in 2020. Only increase if you know what you are doing.
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.TP
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.B \-Q, --query-port=<query_port>
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Send outbound DNS queries from, and listen for their replies on, the
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diff --git a/src/config.h b/src/config.h
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index 492c02f..f6d96db 100644
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--- a/src/config.h
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+++ b/src/config.h
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@@ -19,7 +19,7 @@
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#define CHILD_LIFETIME 150 /* secs 'till terminated (RFC1035 suggests > 120s) */
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#define TCP_MAX_QUERIES 100 /* Maximum number of queries per incoming TCP connection */
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#define TCP_BACKLOG 32 /* kernel backlog limit for TCP connections */
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-#define EDNS_PKTSZ 4096 /* default max EDNS.0 UDP packet from RFC5625 */
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+#define EDNS_PKTSZ 1232 /* default max EDNS.0 UDP packet from from /dnsflagday.net/2020 */
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#define SAFE_PKTSZ 1232 /* "go anywhere" UDP packet size, see https://dnsflagday.net/2020/ */
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#define KEYBLOCK_LEN 40 /* choose to minimise fragmentation when storing DNSSEC keys */
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#define DNSSEC_WORK 50 /* Max number of queries to validate one question */
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--
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2.39.2
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