1 files changed, 10 insertions, 0 deletions

diff --git a/sshd.c b/sshd.c
index 9019411ac..27c38ba53 100644
--- a/sshd.c
+++ b/sshd.c
@@ -976,6 +976,16 @@ server_listen(void)
                     &on, sizeof(on)) == -1)
                         error("setsockopt SO_REUSEADDR: %s", strerror(errno));
 
+#ifdef IPV6_V6ONLY
+                /* Only communicate in IPv6 over AF_INET6 sockets. */
+                if (ai->ai_family == AF_INET6) {
+                        if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY,
+                            &on, sizeof(on)) == -1)
+                                error("setsockopt IPV6_V6ONLY: %s",
+                                    strerror(errno));
+                }
+#endif
+
                 debug("Bind to port %s on %s.", strport, ntop);
 
                 /* Bind the socket to the desired port. */