diff --git a/clatd.c b/clatd.c
index 4a34bf3..7ec3454 100644
--- a/clatd.c
+++ b/clatd.c
@@ -182,7 +182,19 @@
  *   tunnel - tun device data
  *   mark - the socket mark to use for the sending raw socket
  */
-void open_sockets(struct tun_data *tunnel) {
+void open_sockets(struct tun_data *tunnel, uint32_t mark) {
+  int rawsock = socket(AF_INET6, SOCK_RAW | SOCK_NONBLOCK | SOCK_CLOEXEC, IPPROTO_RAW);
+  if (rawsock < 0) {
+    logmsg(ANDROID_LOG_FATAL, "raw socket failed: %s", strerror(errno));
+    exit(1);
+  }
+
+  if (mark != MARK_UNSET && setsockopt(rawsock, SOL_SOCKET, SO_MARK, &mark, sizeof(mark)) < 0) {
+    logmsg(ANDROID_LOG_ERROR, "could not set mark on raw socket: %s", strerror(errno));
+  }
+
+  tunnel->write_fd6 = rawsock;
+
   // Will eventually be bound to htons(ETH_P_IPV6) protocol,
   // but only after appropriate bpf filter is attached.
   tunnel->read_fd6 = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, 0);