ipv6only
diff --git a/src/core/ngx_connection.c b/src/core/ngx_connection.c
index 804ab09..f413ffb 100644
--- a/src/core/ngx_connection.c
+++ b/src/core/ngx_connection.c
@@ -282,6 +282,23 @@
                 return NGX_ERROR;
             }
 
+#if (NGX_HAVE_INET6 && defined IPV6_V6ONLY)
+
+            if (ls[i].sockaddr->sa_family == AF_INET6 && ls[i].ipv6only) {
+                int  ipv6only;
+
+                ipv6only = (ls[i].ipv6only == 1);
+
+                if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
+                               (const void *) &ipv6only, sizeof(int))
+                    == -1)
+                {
+                    ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,
+                                  "setsockopt(IPV6_V6ONLY) %V failed, ignored",
+                                  &ls[i].addr_text);
+                }
+            }
+#endif
             /* TODO: close on exit */
 
             if (!(ngx_event_flags & NGX_USE_AIO_EVENT)) {
diff --git a/src/core/ngx_connection.h b/src/core/ngx_connection.h
index 171078b..cc6a929 100644
--- a/src/core/ngx_connection.h
+++ b/src/core/ngx_connection.h
@@ -56,6 +56,10 @@
     unsigned            shared:1;    /* shared between threads or processes */
     unsigned            addr_ntop:1;
 
+#if (NGX_HAVE_INET6 && defined IPV6_V6ONLY)
+    unsigned            ipv6only:2;
+#endif
+
 #if (NGX_HAVE_DEFERRED_ACCEPT)
     unsigned            deferred_accept:1;
     unsigned            delete_deferred:1;
diff --git a/src/http/ngx_http.c b/src/http/ngx_http.c
index 626686c..d519bf9 100644
--- a/src/http/ngx_http.c
+++ b/src/http/ngx_http.c
@@ -1768,6 +1768,10 @@
     ls->deferred_accept = addr->listen_conf->deferred_accept;
 #endif
 
+#if (NGX_HAVE_INET6 && defined IPV6_V6ONLY)
+    ls->ipv6only = addr->listen_conf->ipv6only;
+#endif
+
     return ls;
 }
 
diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index a2d4e86..2c3992b 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -3332,6 +3332,45 @@
             continue;
         }
 
+        if (ngx_strncmp(value[n].data, "ipv6only=o", 10) == 0) {
+#if (NGX_HAVE_INET6 && defined IPV6_V6ONLY)
+            struct sockaddr  *sa;
+
+            sa = (struct sockaddr *) ls->sockaddr;
+
+            if (sa->sa_family == AF_INET6) {
+
+                if (ngx_strcmp(&value[n].data[10], "n") == 0) {
+                    ls->conf.ipv6only = 1;
+
+                } else if (ngx_strcmp(&value[n].data[10], "ff") == 0) {
+                    ls->conf.ipv6only = 2;
+
+                } else {
+                    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                                       "invalid ipv6only flags \"%s\"",
+                                       &value[n].data[9]);
+                    return NGX_CONF_ERROR;
+                }
+
+                ls->conf.bind = 1;
+
+            } else {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                                   "ipv6only is not supported "
+                                   "on addr \"%s\", ignored",
+                                   ls->conf.addr);
+            }
+
+            continue;
+#else
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "bind ipv6only is not supported "
+                               "on this platform");
+            return NGX_CONF_ERROR;
+#endif
+        }
+
         if (ngx_strcmp(value[n].data, "ssl") == 0) {
 #if (NGX_HTTP_SSL)
             ls->conf.ssl = 1;
diff --git a/src/http/ngx_http_core_module.h b/src/http/ngx_http_core_module.h
index 7ad18ed..705659d 100644
--- a/src/http/ngx_http_core_module.h
+++ b/src/http/ngx_http_core_module.h
@@ -44,6 +44,9 @@
 #if (NGX_HTTP_SSL)
     unsigned                   ssl:1;
 #endif
+#if (NGX_HAVE_INET6 && defined IPV6_V6ONLY)
+    unsigned                   ipv6only:2;
+#endif
 
     int                        backlog;
     int                        rcvbuf;