Implements TTL security for OSPF and RIP.

Interfaces for OSPF and RIP could be configured to use (and request)
TTL 255 for traffic to direct neighbors.

Thanks to Simon Dickhoven for the original patch for RIPng.

3 files changed, 24 insertions, 4 deletions

diff --git a/proto/rip/config.Y b/proto/rip/config.Y
index ec82aa3d..791c43a2 100644
--- a/proto/rip/config.Y
+++ b/proto/rip/config.Y
@@ -22,12 +22,18 @@ CF_DEFINES
 #define RIP_CFG ((struct rip_proto_config *) this_proto)
 #define RIP_IPATT ((struct rip_patt *) this_ipatt)
 
+#ifdef IPV6
+#define RIP_DEFAULT_TTL_SECURITY 2
+#else
+#define RIP_DEFAULT_TTL_SECURITY 0
+#endif
+
 CF_DECLS
 
 CF_KEYWORDS(RIP, INFINITY, METRIC, PORT, PERIOD, GARBAGE, TIMEOUT,
 	    MODE, BROADCAST, MULTICAST, QUIET, NOLISTEN, VERSION1, 
-	    AUTHENTICATION, NONE, PLAINTEXT, MD5,
-	    HONOR, NEVER, NEIGHBOR, ALWAYS, TX, PRIORITY,
+	    AUTHENTICATION, NONE, PLAINTEXT, MD5, TTL, SECURITY,
+	    HONOR, NEVER, NEIGHBOR, ALWAYS, TX, PRIORITY, ONLY,
 	    RIP_METRIC, RIP_TAG)
 
 %type <i> rip_mode rip_auth
@@ -78,6 +84,8 @@ rip_iface_item:
  | MODE rip_mode { RIP_IPATT->mode |= $2; }
  | TX tos { RIP_IPATT->tx_tos = $2; }
  | TX PRIORITY expr { RIP_IPATT->tx_priority = $3; }
+ | TTL SECURITY bool { RIP_IPATT->ttl_security = $3; }
+ | TTL SECURITY TX ONLY { RIP_IPATT->ttl_security = 2; }
  ;
 
 rip_iface_opts: 
@@ -98,6 +106,7 @@ rip_iface_init:
      RIP_IPATT->metric = 1;
      RIP_IPATT->tx_tos = IP_PREC_INTERNET_CONTROL;
      RIP_IPATT->tx_priority = sk_priority_control;
+     RIP_IPATT->ttl_security = RIP_DEFAULT_TTL_SECURITY;
    }
  ;
 
diff --git a/proto/rip/rip.c b/proto/rip/rip.c
index c09eae79..3ec070b3 100644
--- a/proto/rip/rip.c
+++ b/proto/rip/rip.c
@@ -480,6 +480,14 @@ rip_rx(sock *s, int size)
   iface = i->iface;
 #endif
 
+  if (i->check_ttl && (s->ttl < 255))
+  {
+    log( L_REMOTE "%s: Discarding packet with TTL %d (< 255) from %I on %s",
+	 p->name, s->ttl, s->faddr, i->iface->name);
+    return 1;
+  }
+
+
   CHK_MAGIC;
   DBG( "RIP: message came: %d bytes from %I via %s\n", size, s->faddr, i->iface ? i->iface->name : "(dummy)" );
   size -= sizeof( struct rip_packet_heading );
@@ -686,6 +694,7 @@ new_iface(struct proto *p, struct iface *new, unsigned long flags, struct iface_
     rif->mode = PATT->mode;
     rif->metric = PATT->metric;
     rif->multicast = (!(PATT->mode & IM_BROADCAST)) && (flags & IF_MULTICAST);
+    rif->check_ttl = (PATT->ttl_security == 1);
   }
   /* lookup multicasts over unnumbered links - no: rip is not defined over unnumbered links */
 
@@ -706,10 +715,10 @@ new_iface(struct proto *p, struct iface *new, unsigned long flags, struct iface_
   rif->sock->dport = P_CF->port;
   if (new)
     {
-      rif->sock->ttl = 1;
       rif->sock->tos = PATT->tx_tos;
       rif->sock->priority = PATT->tx_priority;
-      rif->sock->flags = SKF_LADDR_RX;
+      rif->sock->ttl = PATT->ttl_security ? 255 : 1;
+      rif->sock->flags = SKF_LADDR_RX | (rif->check_ttl ? SKF_TTL_RX : 0);
     }
 
   if (new) {
diff --git a/proto/rip/rip.h b/proto/rip/rip.h
index 2cce8c81..6e0d5aad 100644
--- a/proto/rip/rip.h
+++ b/proto/rip/rip.h
@@ -114,6 +114,7 @@ struct rip_interface {
   struct rip_connection *busy;
   int metric;			/* You don't want to put struct rip_patt *patt here -- think about reconfigure */
   int mode;
+  int check_ttl;		/* Check incoming packets for TTL 255 */
   int triggered;
   struct object_lock *lock;
   int multicast;
@@ -130,6 +131,7 @@ struct rip_patt {
 #define IM_VERSION1 16
   int tx_tos;
   int tx_priority;
+  int ttl_security;	/* bool + 2 for TX only (send, but do not check on RX) */
 };
 
 struct rip_proto_config {