From 417ae050a7dfb6d6d1e227bbe5817992949376f7 Mon Sep 17 00:00:00 2001
From: catvayor <catvayor@katvayor.net>
Date: Sun, 23 Feb 2025 21:15:42 +0100
Subject: [PATCH] fix: multiple interface with same IP

---
 src/lib/dhcp/pkt_filter.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/lib/dhcp/pkt_filter.cc b/src/lib/dhcp/pkt_filter.cc
index d6360984ef..4dfdea59c7 100644
--- a/src/lib/dhcp/pkt_filter.cc
+++ b/src/lib/dhcp/pkt_filter.cc
@@ -24,6 +24,14 @@ PktFilter::openFallbackSocket(const isc::asiolink::IOAddress& addr,
                   " address " << addr << ", port " << port
                   << ", reason: " << strerror(errno));
     }
+    // allow address to be reused
+    int oneopt = 1;
+    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &oneopt, sizeof(oneopt))) {
+        close(sock);
+        isc_throw(SocketConfigError, "failed to set SO_REUSEADDR socket for"
+                  " address " << addr << ", port " << port
+                  << ", reason: " << strerror(errno));
+    }
     // Set the close-on-exec flag.
     if (fcntl(sock, F_SETFD, FD_CLOEXEC) < 0) {
         close(sock);
-- 
2.47.1