diff -u dnsmasq-2.75/debian/changelog dnsmasq-2.75/debian/changelog
--- dnsmasq-2.75/debian/changelog
+++ dnsmasq-2.75/debian/changelog
@@ -1,3 +1,12 @@
+dnsmasq (2.75-1ubuntu0.16.04.2) xenial; urgency=medium
+
+  * Add two upstream patches to fix binding to an interface being
+    destroyed and recreated. LP: #1639776.
+      + 2675f2061525bc954be14988d64384b74aa7bf8b
+      + 16800ea072dd0cdf14d951c4bb8d2808b3dfe53d
+
+ -- Nishanth Aravamudan <nish.aravamudan@canonical.com>  Mon, 27 Mar 2017 17:22:13 -0700
+
 dnsmasq (2.75-1ubuntu0.16.04.1) xenial-security; urgency=medium
 
   * SECURITY UPDATE: denial of service via crafted CNAME (LP: #1581181)
only in patch2:
unchanged:
--- dnsmasq-2.75.orig/src/dnsmasq.h
+++ dnsmasq-2.75/src/dnsmasq.h
@@ -492,6 +492,7 @@
   int fd;
   union mysockaddr source_addr;
   char interface[IF_NAMESIZE+1];
+  unsigned int ifindex, used;
   struct serverfd *next;
 };
 
only in patch2:
unchanged:
--- dnsmasq-2.75.orig/src/network.c
+++ dnsmasq-2.75/src/network.c
@@ -1191,6 +1191,7 @@
 static struct serverfd *allocate_sfd(union mysockaddr *addr, char *intname)
 {
   struct serverfd *sfd;
+  unsigned int ifindex = 0;
   int errsave;
 
   /* when using random ports, servers which would otherwise use
@@ -1211,11 +1212,15 @@
 	return NULL;
 #endif
     }
+
+  if (intname && strlen(intname) != 0)
+    ifindex = if_nametoindex(intname); /* index == 0 when not binding to an interface */
       
   /* may have a suitable one already */
   for (sfd = daemon->sfds; sfd; sfd = sfd->next )
     if (sockaddr_isequal(&sfd->source_addr, addr) &&
-	strcmp(intname, sfd->interface) == 0)
+	strcmp(intname, sfd->interface) == 0 &&
+	ifindex == sfd->ifindex) 
       return sfd;
   
   /* need to make a new one. */
@@ -1237,11 +1242,13 @@
       errno = errsave;
       return NULL;
     }
-    
+
   strcpy(sfd->interface, intname); 
   sfd->source_addr = *addr;
   sfd->next = daemon->sfds;
+  sfd->ifindex = ifindex;
   daemon->sfds = sfd;
+
   return sfd; 
 }
 
@@ -1417,12 +1424,16 @@
 {
   struct irec *iface;
   struct server *serv;
+  struct serverfd *sfd, *tmp, **up;
   int port = 0;
 
   /* interface may be new since startup */
   if (!option_bool(OPT_NOWILD))
     enumerate_interfaces(0);
   
+  for (sfd = daemon->sfds; sfd; sfd = sfd->next)
+    sfd->used = 0;
+
   for (serv = daemon->servers; serv; serv = serv->next)
     {
        if (!(serv->flags & (SERV_LITERAL_ADDRESS | SERV_NO_ADDR | SERV_USE_RESOLV | SERV_NO_REBIND)))
@@ -1458,6 +1469,9 @@
 	      serv->flags |= SERV_MARK;
 	      continue;
 	    }
+	  
+	  if (serv->sfd)
+	    serv->sfd->used = 1;
 	}
       
       if (!(serv->flags & SERV_NO_REBIND) && !(serv->flags & SERV_LITERAL_ADDRESS))
@@ -1490,6 +1504,20 @@
 	}
     }
 
+  /* Remove unused sfds */
+  for (sfd = daemon->sfds, up = &daemon->sfds; sfd; sfd = tmp)
+    {
+       tmp = sfd->next;
+       if (!sfd->used) 
+	{
+	  *up = sfd->next;
+	  close(sfd->fd);
+	  free(sfd);
+	} 
+      else
+	up = &sfd->next;
+    }
+  
   cleanup_servers();
 }