diff --git a/beacon_chain/conf.nim b/beacon_chain/conf.nim
index 3f6a7dd18..72ab42dd3 100644
--- a/beacon_chain/conf.nim
+++ b/beacon_chain/conf.nim
@@ -60,6 +60,10 @@ type
         desc: "UDP listening port",
         defaultValue: config.defaultPort().}: int
 
+      nat* {.
+        desc: "Specify method to use for determining public address. Must be one of: any, extip:<IP>"
+        defaultValue: "any" .}: string
+
       validators* {.
         required
         desc: "Path to a validator private key, as generated by validator_keygen"
diff --git a/beacon_chain/eth2_network.nim b/beacon_chain/eth2_network.nim
index 01d96896e..ffdd2a2da 100644
--- a/beacon_chain/eth2_network.nim
+++ b/beacon_chain/eth2_network.nim
@@ -1,5 +1,5 @@
 import
-  options, chronos, json_serialization,
+  options, chronos, json_serialization, strutils,
   spec/digest, version, conf
 
 const
@@ -19,6 +19,14 @@ when useRLPx:
 
   template libp2pProtocol*(name, version: string) {.pragma.}
 
+  func parseNat(nat: string): IpAddress =
+    # TODO we should try to discover the actual external IP, in case we're
+    #      behind a nat / upnp / etc..
+    if nat.startsWith("extip:"):
+      parseIpAddress(nat[6..^1])
+    else:
+      parseIpAddress("127.0.0.1")
+
   proc writeValue*(writer: var JsonWriter, value: BootstrapAddr) {.inline.} =
     writer.writeValue $value
 
@@ -36,7 +44,7 @@ when useRLPx:
 
     let
       keys = KeyPair(seckey: privKey, pubkey: privKey.getPublicKey())
-      address = Address(ip: parseIpAddress("127.0.0.1"),
+      address = Address(ip: parseNat(conf.nat),
                         tcpPort: Port conf.tcpPort,
                         udpPort: Port conf.udpPort)
 
diff --git a/tests/simulation/run_node.sh b/tests/simulation/run_node.sh
index fe1c6ba69..a1662327c 100755
--- a/tests/simulation/run_node.sh
+++ b/tests/simulation/run_node.sh
@@ -14,6 +14,7 @@ DATA_DIR=$SIMULATION_DIR/node-${1}
 
 V_PREFIX="$VALIDATORS_DIR/v$(printf '%06d' ${1})"
 PORT=$(printf '5%04d' ${1})
+MYIP=$(curl -s ifconfig.me)
 
 $BEACON_NODE_BIN \
   --network:ephemeralNetwork \
@@ -30,5 +31,6 @@ $BEACON_NODE_BIN \
   --validator:${V_PREFIX}9.privkey \
   --tcpPort:$PORT \
   --udpPort:$PORT \
+  --nat:extip:$MYIP \
   --stateSnapshot:$SNAPSHOT_FILE \
   $BOOTSTRAP_NODES_FLAG