diff --git a/src/bin/fullnode.rs b/src/bin/fullnode.rs
index 434baab116302b..e88e42e998ec1c 100644
--- a/src/bin/fullnode.rs
+++ b/src/bin/fullnode.rs
@@ -73,11 +73,19 @@ fn main() -> () {
     }
 
     let leader_pubkey = keypair.pubkey();
-    let repl_clone = repl_data.clone();
 
     let ledger_path = matches.value_of("ledger").unwrap();
 
-    let mut node = TestNode::new_with_bind_addr(repl_data, bind_addr);
+    let mut node = if let Some(_t) = matches.value_of("testnet") {
+        TestNode::new_with_external_ip(leader_pubkey, repl_data.contact_info.ncp.ip(), 0)
+    } else {
+        TestNode::new_with_external_ip(
+            leader_pubkey,
+            repl_data.contact_info.ncp.ip(),
+            repl_data.contact_info.ncp.port(),
+        )
+    };
+    let repl_clone = node.data.clone();
     let mut drone_addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), DRONE_PORT);
     let fullnode = if let Some(t) = matches.value_of("testnet") {
         let testnet_address_string = t.to_string();
diff --git a/src/crdt.rs b/src/crdt.rs
index fd3345081a427e..ea201c2e1b96d9 100644
--- a/src/crdt.rs
+++ b/src/crdt.rs
@@ -20,6 +20,7 @@ use counter::Counter;
 use hash::Hash;
 use ledger::LedgerWindow;
 use log::Level;
+use nat::udp_random_bind;
 use packet::{to_blob, Blob, BlobRecycler, SharedBlob, BLOB_SIZE};
 use pnet_datalink as datalink;
 use rand::{thread_rng, RngCore};
@@ -30,7 +31,7 @@ use std;
 use std::collections::HashMap;
 use std::collections::VecDeque;
 use std::io::Cursor;
-use std::net::{IpAddr, SocketAddr, UdpSocket};
+use std::net::{IpAddr, Ipv4Addr, SocketAddr, UdpSocket};
 use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
 use std::sync::{Arc, RwLock};
 use std::thread::{sleep, Builder, JoinHandle};
@@ -1353,6 +1354,69 @@ impl TestNode {
             },
         }
     }
+    pub fn new_with_external_ip(pubkey: Pubkey, ip: IpAddr, ncp_port: u16) -> TestNode {
+        fn bind() -> (u16, UdpSocket) {
+            match udp_random_bind(8100, 10000, 5) {
+                Ok(socket) => (socket.local_addr().unwrap().port(), socket),
+                Err(err) => {
+                    panic!("Failed to bind to {:?}", err);
+                }
+            }
+        };
+
+        fn bind_to(port: u16) -> UdpSocket {
+            let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)), port);
+            match UdpSocket::bind(addr) {
+                Ok(socket) => socket,
+                Err(err) => {
+                    panic!("Failed to bind to {:?}: {:?}", addr, err);
+                }
+            }
+        };
+
+        let (gossip_port, gossip) = if ncp_port != 0 {
+            (ncp_port, bind_to(ncp_port))
+        } else {
+            bind()
+        };
+        let (replicate_port, replicate) = bind();
+        let (requests_port, requests) = bind();
+        let (transaction_port, transaction) = bind();
+        let (repair_port, repair) = bind();
+
+        // Responses are sent from the same Udp port as requests are received
+        // from, in hopes that a NAT sitting in the middle will route the
+        // response Udp packet correctly back to the requester.
+        let respond = requests.try_clone().unwrap();
+
+        let gossip_send = UdpSocket::bind("0.0.0.0:0").unwrap();
+        let broadcast = UdpSocket::bind("0.0.0.0:0").unwrap();
+        let retransmit = UdpSocket::bind("0.0.0.0:0").unwrap();
+
+        let node_info = NodeInfo::new(
+            pubkey,
+            SocketAddr::new(ip.clone(), gossip_port),
+            SocketAddr::new(ip.clone(), replicate_port),
+            SocketAddr::new(ip.clone(), requests_port),
+            SocketAddr::new(ip.clone(), transaction_port),
+            SocketAddr::new(ip.clone(), repair_port),
+        );
+
+        TestNode {
+            data: node_info,
+            sockets: Sockets {
+                gossip,
+                gossip_send,
+                requests,
+                replicate,
+                transaction,
+                respond,
+                broadcast,
+                repair,
+                retransmit,
+            },
+        }
+    }
 }
 
 fn report_time_spent(label: &str, time: &Duration, extra: &str) {