Let's have a directory for useful patches for people to apply themselves

useful-patches/0001-Backport-5.14-lowest-address-is-not-broadcast.patch

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+From 323c87d4c2de7598ac810632450816732056b111 Mon Sep 17 00:00:00 2001
+From: Seth Schoen <[email protected]>
+Date: Sun, 22 Jan 2023 14:39:24 -0800
+Subject: [PATCH] Backport 5.14: lowest-address is not broadcast
+
+Allow the lowest address in a network segment to be used as an
+ordinary unicast address, not a duplicate broadcast address.
+
+Signed-off-by: Seth David Schoen <[email protected]>
+Suggested-by: John Gilmore <[email protected]>
+---
+ net/ipv4/fib_frontend.c | 4 +---
+ 1 file changed, 1 insertion(+), 3 deletions(-)
+
+diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
+index 5f786ef662ea..0b3fadc002d6 100644
+--- a/net/ipv4/fib_frontend.c
++++ b/net/ipv4/fib_frontend.c
+@@ -1129,10 +1129,8 @@ void fib_add_ifaddr(struct in_ifaddr *ifa)
+ 				  prefix, ifa->ifa_prefixlen, prim,
+ 				  ifa->ifa_rt_priority);
+ 
+-		/* Add network specific broadcasts, when it takes a sense */
++		/* Add the network broadcast address, when it makes sense */
+ 		if (ifa->ifa_prefixlen < 31) {
+-			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32,
+-				  prim, 0);
+ 			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
+ 				  32, prim, 0);
+ 			arp_invalidate(dev, prefix | ~mask, false);
+-- 
+2.25.1
+

useful-patches/README.md

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+This directory contains patches which are probably not going to be merged
+upstream for various reasons (or were not merged upstream in time for
+particular software releases), but if you're building a relevant software
+version yourself, you can still make use of them.
+
+* 0001-Backport-5.14-lowest-address-is-not-broadcast.patch
+
+This patch is included with Linux 5.14 and later, and makes the lowest
+address on an IPv4 segment non-broadcast.  You can apply this version
+to a Linux 5.10 LTS kernel (or likely to other kernel versions prior
+to 5.14).