diff --git a/libc/bionic/if_indextoname.c b/libc/bionic/if_indextoname.c
new file mode 100644
index 0000000..dc08b28
--- /dev/null
+++ b/libc/bionic/if_indextoname.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <string.h>
+#include <unistd.h>
+#include <linux/sockios.h>
+#include <net/if.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <errno.h>
+
+/*
+ * Map an interface index into its name.
+ * Returns NULL on error.
+ */
+char*
+if_indextoname(unsigned ifindex, char *ifname)
+{
+    int index;
+    int ctl_sock;
+    struct ifreq ifr;
+    char*  ret = NULL;
+
+    memset(&ifr, 0, sizeof(struct ifreq));
+    ifr.ifr_ifindex = ifindex;
+
+    if ((ctl_sock = socket(AF_INET, SOCK_DGRAM, 0)) >= 0) {
+        if (ioctl(ctl_sock, SIOCGIFNAME, &ifr) >= 0) {
+            ret = strncpy (ifname, ifr.ifr_name, IFNAMSIZ);
+        } else {
+            /* Posix requires ENXIO */
+            if (errno == ENODEV)
+                errno = ENXIO;
+        }
+        close(ctl_sock);
+    }
+    return ret;
+}