TCP MD5SIG patch

from http://www.gossamer-threads.com/lists/quagga/dev/15611

     [clear_shim]           Re: [quagga-users 9315] New md5 signature patch for bgp... quagga_md5_bsd_linux_v9.diff Remove Highlighting [In reply to]
     mhw at wittsend        ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

     Jan 28, 2008, 12:55 PM And, of course, the moment I send off a patch against 0.99.9 and claim
                            it should patch the CVS, I find out it does not.
     Post #2 of 3 (192
     views)                 On Mon, 2008-01-28 at 14:50 -0500, Michael H. Warfield wrote:
     Permalink              > Hello all!

                            > Building on the efforts of Leigh Brown and the earlier works on an MD5
                            > signature patch for bgpd, I've incorporated the autoconf efforts by
                            > Sargun Dhillon on top of my own changes for IPv6 along with filling in a
                            > few missing spots in the autoconf stuff myself. Leigh had released a v7
                            > and I subsequently released a v8 patch for md5 signatures for Linux and
                            > BSD to deal with conflicts with IPv6. This is now a v9 patch
                            > incorporating some of the changes from Sargun and adding a few of my own
                            > to complete the autoconf changes.

                            > This patch is still against 0.99.9 but should patch cleanly against
                            > CVS.

                            Attached is the patch against CVS. It does NOT have a patch for
                            config.h.in (that was a mistake on my part, it's not in CVS, it's
                            generated but it's not regenerated if you are working from the releases
                            and don't rerun autoheader) and fixes a problem with a header file and
                            some alignments.

[cl]                        > This adds a configure option, --enable-tcp-md5, to enable tcp md5                                                             [cl]
                            > signatures. This is not qualified against the operating system on which
                            > it is being built. The patch should work on BSD and Linux. Other
                            > operation systems are a crap shoot. I don't know. I presume some other
                            > errors will occur on other operating systems which do not support MD5
                            > signatures in this manner. Since they're not supported now, this is no
                            > great loss. Someone might want to test this in other environments,
                            > though, and enhance it for those other environments.
                            >
                            > Attached...
                            >
                            > quagga_md5_bsd_linux_v9.diff
                            >
                            > http://www.wittsend.com/mhw/md5sig/quagga_md5_bsd_linux_v9.diff
                            >
                            > Is there anything left that needs to be done before this can be
                            > committed to CVS? Can someone with commit privs please do the honors?

                            Mike
                            --
                            Michael H. Warfield (AI4NB) | (770) 985-6132 | mhw[at]WittsEnd.com
                            /\/\|=mhw=|\/\/ | (678) 463-0932 | http://www.wittsend.com/mhw/
                            NIC whois: MHW9 | An optimist believes we live in the best of all
                            PGP Key: 0xDF1DD471 | possible worlds. A pessimist is sure of it!

               Attachments: [unknown] quagga_cvs_md5_bsd_linux_v9.diff (18.4 KB)
<http://www.gossamer-threads.com/lists/engine?do=post_attachment;postatt_id=1184;list=quagga>
                            [unknown] signature.asc (0.30 KB)
<http://www.gossamer-threads.com/lists/engine?do=post_attachment;postatt_id=1185;list=quagga>

Signed-off-by: Tom Grennan <tgrennan@vyatta.com>

8 files changed, 421 insertions, 0 deletions

diff --git a/bgpd/bgp_network.c b/bgpd/bgp_network.c
index 8452545d..4289ce20 100644
--- a/bgpd/bgp_network.c
+++ b/bgpd/bgp_network.c
@@ -22,6 +22,7 @@ Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 
 #include "thread.h"
 #include "sockunion.h"
+#include "sockopt.h"
 #include "memory.h"
 #include "log.h"
 #include "if.h"
@@ -38,6 +39,34 @@ Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 extern struct zebra_privs_t bgpd_privs;
 
 
+#if defined(HAVE_TCP_MD5SIG)
+/*
+ * Set MD5 key for the socket, for the given IPv4 peer address.
+ * If the password is NULL or zero-length, the option will be disabled.
+ */
+int
+bgp_md5_set (int sock, struct sockaddr_in *sin, const char *password)
+{
+  int ret, en;
+
+  if ( bgpd_privs.change (ZPRIVS_RAISE) )
+    zlog_err ("bgp_md5_set: could not raise privs");
+
+  ret = sockopt_tcp_signature (sock, sin, password);
+  en  = errno;
+
+  if (bgpd_privs.change (ZPRIVS_LOWER) )
+    zlog_err ("bgp_md5_set: could not lower privs");
+
+  if (ret < 0)
+    zlog (NULL, LOG_WARNING, "can't set TCP_MD5SIG option on socket %d: %s",
+	  sock, safe_strerror (en));
+
+  return ret;
+}
+
+#endif /* HAVE_TCP_MD5SIG */
+
 /* Accept bgp connection. */
 static int
 bgp_accept (struct thread *thread)
@@ -238,6 +267,12 @@ bgp_connect (struct peer *peer)
   sockopt_reuseaddr (peer->fd);
   sockopt_reuseport (peer->fd);
 
+#ifdef HAVE_TCP_MD5SIG
+  if (CHECK_FLAG (peer->flags, PEER_FLAG_PASSWORD))
+    if (sockunion_family (&peer->su) == AF_INET)
+      bgp_md5_set (peer->fd, &peer->su.sin, peer->password);
+#endif /* HAVE_TCP_MD5SIG */
+
   /* Bind socket. */
   bgp_bind (peer);
 
@@ -288,6 +323,10 @@ bgp_socket (struct bgp *bgp, unsigned short port, char *address)
   struct addrinfo req;
   struct addrinfo *ainfo;
   struct addrinfo *ainfo_save;
+#if defined(HAVE_TCP_MD5SIG) && defined(IPV6_V6ONLY)
+  struct sockaddr_in sin;
+  int socklen, on = 1;
+#endif
   int sock = 0;
   char port_str[BUFSIZ];
 
@@ -323,6 +362,21 @@ bgp_socket (struct bgp *bgp, unsigned short port, char *address)
       sockopt_reuseaddr (sock);
       sockopt_reuseport (sock);
       
+#if defined(HAVE_TCP_MD5SIG) && defined(IPV6_V6ONLY)
+/*	We can not apply MD5SIG to an IPv6 socket.  If this is an AF_INET6
+	socket, we'll have to create another socket for IPv4*/
+
+      if (ainfo->ai_family == AF_INET6) {
+/*	Mark this one for IPv6 only	*/
+          ret = setsockopt (sock, IPPROTO_IPV6, IPV6_V6ONLY, 
+		    (void *) &on, sizeof (on));
+          if( ret < 0 ) {
+              en = errno;
+	      zlog_err ("setsockopt V6ONLY: %s", safe_strerror (en));
+          }
+      }
+#endif
+
       if (bgpd_privs.change (ZPRIVS_RAISE) )
         zlog_err ("bgp_socket: could not raise privs");
 
@@ -346,7 +400,65 @@ bgp_socket (struct bgp *bgp, unsigned short port, char *address)
 	  continue;
 	}
 
+#if defined(HAVE_TCP_MD5SIG) && defined(IPV6_V6ONLY)
+      thread_add_read (master, bgp_accept, bgp, sock);
+
+      if (ainfo->ai_family != AF_INET6)
+	continue;
+
+      /* If first socket was an IPv6 socket, we need to create an IPv4
+	socket for use by the TCP_MD5SIG logic.  This code is blatently
+	copied and modified from the alternate IPv4 only code from below... */
+
+      sock = socket (AF_INET, SOCK_STREAM, 0);
+      if (sock < 0)
+        {
+          zlog_err ("socket: %s", safe_strerror (errno));
+          continue;
+        }
+
+      sockopt_reuseaddr (sock);
+      sockopt_reuseport (sock);
+
+      memset (&sin, 0, sizeof (struct sockaddr_in));
+
+      sin.sin_family = AF_INET;
+      sin.sin_port = htons (port);
+      socklen = sizeof (struct sockaddr_in);
+#ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
+      sin.sin_len = socklen;
+#endif /* HAVE_STRUCT_SOCKADDR_IN_SIN_LEN */
+
+      if ( bgpd_privs.change (ZPRIVS_RAISE) )
+        zlog_err ("bgp_socket: could not raise privs");
+
+      ret = bind (sock, (struct sockaddr *) &sin, socklen);
+      en = errno;
+      if (bgpd_privs.change (ZPRIVS_LOWER) )
+	zlog_err ("bgp_bind_address: could not lower privs");
+
+      if (ret < 0)
+	{
+	  zlog_err ("bind: %s", safe_strerror (en));
+	  close(sock);
+	  continue;
+	}
+
+      ret = listen (sock, 3);
+      if (ret < 0)
+	{
+	  zlog_err ("listen: %s", safe_strerror (errno));
+	  close (sock);
+	  continue;
+	}
+#endif
+
+#ifdef HAVE_TCP_MD5SIG
+      bm->sock = sock;
+#endif /* HAVE_TCP_MD5SIG */
+
       thread_add_read (master, bgp_accept, bgp, sock);
+
     }
   while ((ainfo = ainfo->ai_next) != NULL);
 
@@ -413,6 +525,9 @@ bgp_socket (struct bgp *bgp, unsigned short port, char *address)
       close (sock);
       return ret;
     }
+#ifdef HAVE_TCP_MD5SIG
+  bm->sock = sock;
+#endif /* HAVE_TCP_MD5SIG */
 
   thread_add_read (bm->master, bgp_accept, bgp, sock);
 
diff --git a/bgpd/bgp_network.h b/bgpd/bgp_network.h
index b455f574..e7119414 100644
--- a/bgpd/bgp_network.h
+++ b/bgpd/bgp_network.h
@@ -21,6 +21,10 @@ Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 #ifndef _QUAGGA_BGP_NETWORK_H
 #define _QUAGGA_BGP_NETWORK_H
 
+#if defined(HAVE_TCP_MD5SIG)
+extern int bgp_md5_set (int, struct sockaddr_in *, const char *);
+#endif /* HAVE_TCP_MD5SIG */
+
 extern int bgp_socket (struct bgp *, unsigned short, char *);
 extern int bgp_connect (struct peer *);
 extern void bgp_getsockname (struct peer *);
diff --git a/bgpd/bgp_vty.c b/bgpd/bgp_vty.c
index 1481c66d..d42f8121 100644
--- a/bgpd/bgp_vty.c
+++ b/bgpd/bgp_vty.c
@@ -1479,6 +1479,46 @@ ALIAS (no_neighbor_local_as,
        "AS number used as local AS\n"
        "Do not prepend local-as to updates from ebgp peers\n")
 
+#ifdef HAVE_TCP_MD5SIG
+DEFUN (neighbor_password,
+       neighbor_password_cmd,
+       NEIGHBOR_CMD2 "password LINE",
+       NEIGHBOR_STR
+       NEIGHBOR_ADDR_STR2
+       "Set a password\n"
+       "The password\n")
+{
+  struct peer *peer;
+  int ret;
+
+  peer = peer_and_group_lookup_vty (vty, argv[0]);
+  if (! peer)
+    return CMD_WARNING;
+
+  ret = peer_password_set (peer, argv[1]);
+  return bgp_vty_return (vty, ret);
+}
+
+DEFUN (no_neighbor_password,
+       no_neighbor_password_cmd,
+       NO_NEIGHBOR_CMD2 "password",
+       NO_STR
+       NEIGHBOR_STR
+       NEIGHBOR_ADDR_STR2
+       "Set a password\n")
+{
+  struct peer *peer;
+  int ret;
+
+  peer = peer_and_group_lookup_vty (vty, argv[0]);
+  if (! peer)
+    return CMD_WARNING;
+
+  ret = peer_password_unset (peer);
+  return bgp_vty_return (vty, ret);
+}
+#endif /* HAVE_TCP_MD5SIG */
+
 DEFUN (neighbor_activate,
        neighbor_activate_cmd,
        NEIGHBOR_CMD2 "activate",
@@ -8897,6 +8937,12 @@ bgp_vty_init (void)
   install_element (BGP_NODE, &no_neighbor_local_as_val_cmd);
   install_element (BGP_NODE, &no_neighbor_local_as_val2_cmd);
 
+#ifdef HAVE_TCP_MD5SIG
+  /* "neighbor password" commands. */
+  install_element (BGP_NODE, &neighbor_password_cmd);
+  install_element (BGP_NODE, &no_neighbor_password_cmd);
+#endif /* HAVE_TCP_MD5SIG */
+
   /* "neighbor activate" commands. */
   install_element (BGP_NODE, &neighbor_activate_cmd);
   install_element (BGP_IPV4_NODE, &neighbor_activate_cmd);
diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index 128bfef1..c4e54f03 100644
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -788,6 +788,7 @@ peer_new (struct bgp *bgp)
   peer->status = Idle;
   peer->ostatus = Idle;
   peer->weight = 0;
+  peer->password = NULL;
   peer->bgp = bgp;
   peer = peer_lock (peer); /* initial reference */
 
@@ -1202,6 +1203,20 @@ peer_delete (struct peer *peer)
   peer->last_reset = PEER_DOWN_NEIGHBOR_DELETE;
   bgp_stop (peer);
   bgp_fsm_change_status (peer, Deleted);
+
+#ifdef HAVE_TCP_MD5SIG
+  /* Password configuration */
+  if (peer->password)
+    {
+      free (peer->password);
+      peer->password = NULL;
+
+      if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP)
+          && sockunion_family (&peer->su) == AF_INET)
+       bgp_md5_set (bm->sock, &peer->su.sin, NULL);
+    }
+#endif /* HAVE_TCP_MD5SIG */
+
   bgp_timer_set (peer); /* stops all timers for Deleted */
   
   /* Delete from all peer list. */
@@ -1417,6 +1432,27 @@ peer_group2peer_config_copy (struct peer_group *group, struct peer *peer,
   else
     peer->v_routeadv = BGP_DEFAULT_EBGP_ROUTEADV;
 
+#ifdef HAVE_TCP_MD5SIG
+  /* password apply */
+  if (CHECK_FLAG (conf->flags, PEER_FLAG_PASSWORD))
+    {
+      if (peer->password)
+	free (peer->password);
+      peer->password = strdup (conf->password);
+
+      if (sockunion_family (&peer->su) == AF_INET)
+	bgp_md5_set (bm->sock, &peer->su.sin, peer->password);
+    }
+  else if (peer->password)
+    {
+      free (peer->password);
+      peer->password = NULL;
+
+      if (sockunion_family (&peer->su) == AF_INET)
+        bgp_md5_set (bm->sock, &peer->su.sin, NULL);
+    }
+#endif /* HAVE_TCP_MD5SIG */
+
   /* maximum-prefix */
   peer->pmax[afi][safi] = conf->pmax[afi][safi];
   peer->pmax_threshold[afi][safi] = conf->pmax_threshold[afi][safi];
@@ -3379,6 +3415,125 @@ peer_local_as_unset (struct peer *peer)
   return 0;
 }
 
+#ifdef HAVE_TCP_MD5SIG
+/* Set password for authenticating with the peer. */
+int
+peer_password_set (struct peer *peer, const char *password)
+{
+  struct peer_group *group;
+  struct listnode *nn, *nnode;
+  int len = password ? strlen(password) : 0;
+
+  if ((len < PEER_PASSWORD_MINLEN) || (len > PEER_PASSWORD_MAXLEN))
+    return BGP_ERR_INVALID_VALUE;
+
+  if (peer->password && strcmp (peer->password, password) == 0
+      && ! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+	return 0;
+
+  SET_FLAG (peer->flags, PEER_FLAG_PASSWORD);
+  if (peer->password)
+    free (peer->password);
+  peer->password = strdup (password);
+
+  if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+    {
+      if (peer->status == Established)
+          bgp_notify_send (peer, BGP_NOTIFY_CEASE, BGP_NOTIFY_CEASE_CONFIG_CHANGE);
+      else
+        BGP_EVENT_ADD (peer, BGP_Stop);
+
+      if (sockunion_family (&peer->su) == AF_INET)
+	bgp_md5_set (bm->sock, &peer->su.sin, peer->password);
+      return 0;
+    }
+
+  group = peer->group;
+  /* #42# LIST_LOOP (group->peer, peer, nn) */
+  for (ALL_LIST_ELEMENTS (group->peer, nn, nnode, peer))
+    {
+      if (peer->password && strcmp (peer->password, password) == 0)
+	continue;
+
+      SET_FLAG (peer->flags, PEER_FLAG_PASSWORD);
+      if (peer->password)
+        free (peer->password);
+      peer->password = strdup (password);
+
+      if (peer->status == Established)
+        bgp_notify_send (peer, BGP_NOTIFY_CEASE, BGP_NOTIFY_CEASE_CONFIG_CHANGE);
+      else
+        BGP_EVENT_ADD (peer, BGP_Stop);
+
+      if (sockunion_family (&peer->su) == AF_INET)
+	bgp_md5_set (bm->sock, &peer->su.sin, peer->password);
+    }
+
+  return 0;
+}
+
+int
+peer_password_unset (struct peer *peer)
+{
+  struct peer_group *group;
+  struct listnode *nn, *nnode;
+
+  if (! CHECK_FLAG (peer->flags, PEER_FLAG_PASSWORD)
+      && ! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+    return 0;
+
+  if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+    {
+      if (peer_group_active (peer)
+	  && CHECK_FLAG (peer->group->conf->flags, PEER_FLAG_PASSWORD))
+	return BGP_ERR_PEER_GROUP_HAS_THE_FLAG;
+
+      if (peer->status == Established)
+        bgp_notify_send (peer, BGP_NOTIFY_CEASE, BGP_NOTIFY_CEASE_CONFIG_CHANGE);
+      else
+        BGP_EVENT_ADD (peer, BGP_Stop);
+
+      if (sockunion_family (&peer->su) == AF_INET)
+	bgp_md5_set (bm->sock, &peer->su.sin, NULL);
+
+      UNSET_FLAG (peer->flags, PEER_FLAG_PASSWORD);
+      if (peer->password)
+	free (peer->password);
+      peer->password = NULL;
+
+      return 0;
+    }
+
+  UNSET_FLAG (peer->flags, PEER_FLAG_PASSWORD);
+  if (peer->password)
+    free (peer->password);
+  peer->password = NULL;
+
+  group = peer->group;
+  /* #42# LIST_LOOP (group->peer, peer, nn) */
+  for (ALL_LIST_ELEMENTS (group->peer, nn, nnode, peer))
+    {
+      if (! CHECK_FLAG (peer->flags, PEER_FLAG_PASSWORD))
+	continue;
+
+      if (peer->status == Established)
+        bgp_notify_send (peer, BGP_NOTIFY_CEASE, BGP_NOTIFY_CEASE_CONFIG_CHANGE);
+      else
+        BGP_EVENT_ADD (peer, BGP_Stop);
+
+      if (sockunion_family (&peer->su) == AF_INET)
+	bgp_md5_set (bm->sock, &peer->su.sin, NULL);
+
+      UNSET_FLAG (peer->flags, PEER_FLAG_PASSWORD);
+      if (peer->password)
+        free (peer->password);
+      peer->password = NULL;
+    }
+
+  return 0;
+}
+#endif /* HAVE_TCP_MD5SIG */
+
 /* Set distribute list to the peer. */
 int
 peer_distribute_set (struct peer *peer, afi_t afi, safi_t safi, int direct, 
@@ -4416,6 +4571,16 @@ bgp_config_write_peer (struct vty *vty, struct bgp *bgp,
 	    ! CHECK_FLAG (g_peer->flags, PEER_FLAG_SHUTDOWN))
 	  vty_out (vty, " neighbor %s shutdown%s", addr, VTY_NEWLINE);
 
+#ifdef HAVE_TCP_MD5SIG
+      /* Password. */
+      if (CHECK_FLAG (peer->flags, PEER_FLAG_PASSWORD))
+	if (! peer_group_active (peer)
+	    || ! CHECK_FLAG (g_peer->flags, PEER_FLAG_PASSWORD)
+	    || strcmp (peer->password, g_peer->password) != 0)
+	  vty_out (vty, " neighbor %s password %s%s", addr, peer->password,
+		   VTY_NEWLINE);
+#endif /* HAVE_TCP_MD5SIG */
+
       /* BGP port. */
       if (peer->port != BGP_PORT_DEFAULT)
 	vty_out (vty, " neighbor %s port %d%s", addr, peer->port, 
@@ -4951,6 +5116,9 @@ bgp_master_init (void)
   bm->port = BGP_PORT_DEFAULT;
   bm->master = thread_master_create ();
   bm->start_time = time (NULL);
+#ifdef HAVE_TCP_MD5SIG
+  bm->sock = -1;
+#endif /* HAVE_TCP_MD5SIG */
 }
 
 
diff --git a/bgpd/bgpd.h b/bgpd/bgpd.h
index e9fc410f..ef1f860b 100644
--- a/bgpd/bgpd.h
+++ b/bgpd/bgpd.h
@@ -56,6 +56,11 @@ struct bgp_master
 #define BGP_OPT_NO_FIB                   (1 << 0)
 #define BGP_OPT_MULTIPLE_INSTANCE        (1 << 1)
 #define BGP_OPT_CONFIG_CISCO             (1 << 2)
+
+#ifdef HAVE_TCP_MD5SIG
+  /* bgp receive socket */
+  int sock;
+#endif /* HAVE_TCP_MD5SIG */
 };
 
 /* BGP instance structure.  */
@@ -358,6 +363,7 @@ struct peer
 
   /* NSF mode (graceful restart) */
   u_char nsf[AFI_MAX][SAFI_MAX];
+#define PEER_FLAG_PASSWORD                  (1 << 9) /* password */
 
   /* Per AF configuration flags. */
   u_int32_t af_flags[AFI_MAX][SAFI_MAX];
@@ -379,6 +385,9 @@ struct peer
 #define PEER_FLAG_MAX_PREFIX_WARNING        (1 << 15) /* maximum prefix warning-only */
 #define PEER_FLAG_NEXTHOP_LOCAL_UNCHANGED   (1 << 16) /* leave link-local nexthop unchanged */ 
 
+  /* MD5 password */
+  char *password;
+
   /* default-originate route-map.  */
   struct
   {
@@ -534,6 +543,13 @@ struct peer
 #define PEER_RMAP_TYPE_EXPORT         (1 << 7) /* neighbor route-map export */
 };
 
+#if defined(HAVE_TCP_MD5SIG)
+
+#define PEER_PASSWORD_MINLEN	(1)
+#define PEER_PASSWORD_MAXLEN	(80)
+
+#endif /* HAVE_TCP_MD5SIG */
+
 /* This structure's member directly points incoming packet data
    stream. */
 struct bgp_nlri
@@ -924,6 +940,11 @@ extern int peer_route_map_set (struct peer *, afi_t, safi_t, int, const char *);
 extern int peer_route_map_unset (struct peer *, afi_t, safi_t, int);
 
 extern int peer_unsuppress_map_set (struct peer *, afi_t, safi_t, const char *);
+#ifdef HAVE_TCP_MD5SIG
+extern int peer_password_set (struct peer *, const char *);
+extern int peer_password_unset (struct peer *);
+#endif /* HAVE_TCP_MD5SIG */
+
 extern int peer_unsuppress_map_unset (struct peer *, afi_t, safi_t);
 
 extern int peer_maximum_prefix_set (struct peer *, afi_t, safi_t, u_int32_t, u_char, int, u_int16_t);
diff --git a/configure.ac b/configure.ac
index bce20242..81f85a66 100755
--- a/configure.ac
+++ b/configure.ac
@@ -218,6 +218,8 @@ AC_ARG_WITH(libpam,
 [  --with-libpam           use libpam for PAM support in vtysh])
 AC_ARG_ENABLE(tcp-zebra,
 [  --enable-tcp-zebra      enable TCP/IP socket connection between zebra and protocol daemon])
+AC_ARG_ENABLE(tcp-md5,
+[  --enable-tcp-md5        enable TCP/IP md5 in BGPd])
 AC_ARG_ENABLE(opaque-lsa,
 [  --enable-opaque-lsa     enable OSPF Opaque-LSA with OSPFAPI support (RFC2370)])
 AC_ARG_ENABLE(ospfapi,
@@ -288,6 +290,10 @@ if test "${enable_tcp_zebra}" = "yes"; then
   AC_DEFINE(HAVE_TCP_ZEBRA,,Use TCP for zebra communication)
 fi
 
+if test "${enable_tcp_md5}" = "yes"; then
+  AC_DEFINE(HAVE_TCP_MD5SIG,1,Enable TCP MD5 Signatures)
+fi
+
 if test "${enable_opaque_lsa}" = "yes"; then
   AC_DEFINE(HAVE_OPAQUE_LSA,,OSPF Opaque LSA)
 fi
diff --git a/lib/sockopt.c b/lib/sockopt.c
index f8fa946e..985c3a38 100644
--- a/lib/sockopt.c
+++ b/lib/sockopt.c
@@ -480,3 +480,36 @@ sockopt_iphdrincl_swab_systoh (struct ip *iph)
 
   iph->ip_id = ntohs(iph->ip_id);
 }
+
+#if defined(HAVE_TCP_MD5SIG)
+int
+sockopt_tcp_signature (int sock, struct sockaddr_in *sin, const char *password)
+{
+  int keylen = password ? strlen(password) : 0;
+
+#if defined(GNU_LINUX)
+
+  struct tcp_md5sig md5sig;
+
+  bzero ((char *)&md5sig, sizeof(md5sig));
+  memcpy (&md5sig.tcpm_addr, sin, sizeof(*sin));
+  md5sig.tcpm_keylen = keylen;
+  if (keylen)
+    memcpy (md5sig.tcpm_key, password, keylen);
+
+  return setsockopt (sock, IPPROTO_TCP, TCP_MD5SIG, &md5sig, sizeof md5sig);
+
+#else /* !GNU_LINUX */
+
+  int enable = keylen ? (TCP_SIG_SPI_BASE + sin->sin_port) : 0;
+
+  /*
+   * XXX Need to do PF_KEY operation here to add/remove an SA entry,
+   * and add/remove an SP entry for this peer's packet flows also.
+   */
+  return setsockopt (sock, IPPROTO_TCP, TCP_MD5SIG, &enable,
+		     sizeof(enable));
+
+#endif /* !GNU_LINUX */
+}
+#endif /* HAVE_TCP_MD5SIG */
diff --git a/lib/sockopt.h b/lib/sockopt.h
index ebb71430..158f17ac 100644
--- a/lib/sockopt.h
+++ b/lib/sockopt.h
@@ -98,4 +98,32 @@ extern int getsockopt_ifindex (int, struct msghdr *);
 extern void sockopt_iphdrincl_swab_htosys (struct ip *iph);
 extern void sockopt_iphdrincl_swab_systoh (struct ip *iph);
 
+#if defined(HAVE_TCP_MD5SIG)
+
+#if defined(GNU_LINUX) && !defined(TCP_MD5SIG)
+
+/* XXX these will come from <linux/tcp.h> eventually */
+
+#define TCP_MD5SIG		14
+#define TCP_MD5SIG_MAXKEYLEN	80
+
+struct tcp_md5sig {
+        struct sockaddr_storage tcpm_addr;      /* address associated */
+        __u16   __tcpm_pad1;                            /* zero */
+        __u16   tcpm_keylen;                            /* key length */
+        __u32   __tcpm_pad2;                            /* zero */
+        __u8    tcpm_key[TCP_MD5SIG_MAXKEYLEN];         /* key (binary) */
+};
+
+#endif /* defined(GNU_LINUX) && !defined(TCP_MD5SIG) */
+
+#if !defined(GNU_LINUX) && !defined(TCP_SIG_SPI_BASE)
+#define TCP_SIG_SPI_BASE 1000 /* XXX this will go away */
+#endif
+
+extern int sockopt_tcp_signature(int sock, struct sockaddr_in *sin,
+                                 const char *password);
+
+#endif /* HAVE_TCP_MD5SIG */
+
 #endif /*_ZEBRA_SOCKOPT_H */