diff --git a/lib/net/tcp.js b/lib/net/tcp.js
index f939a96..3a51030 100644
--- a/lib/net/tcp.js
+++ b/lib/net/tcp.js
@@ -13,8 +13,6 @@ var assert = require("../_util").assert;
 var PPromise = require("../platform").Promise;
 var BaseTransport = require("./base");
 
-var sockIdCounter = 0;
-
 /**
  * TCP transport constructor.
  * @constructor
@@ -113,6 +111,15 @@ Transport.prototype.connect = function() {
   this._setupClient(client);
 };
 
+// Unmap IPv4-mapped IPv6 addresses.
+function unmap(addr) {
+  if (addr.indexOf("::ffff:") === 0) {
+    return addr.slice(7);
+  } else {
+    return addr;
+  }
+}
+
 Transport.prototype.listen = function() {
   assert(!this._client, "Already connected");
   assert(!this._server, "Already listening");
@@ -122,17 +129,26 @@ Transport.prototype.listen = function() {
   server.listen.apply(server, arguments);
 
   server.on("connection", function(sock) {
-    sock.id = sockIdCounter++;
-    self._clients[sock.id] = sock;
+    var addr = sock.remoteAddress;
+    var port = sock.remotePort;
+    if (self._clients[addr]) {
+      // NOTE(Kagami): Doesn't allow more than one connection per IP.
+      // This may obstruct people behind NAT but we copy PyBitmessage's
+      // behavior here.
+      sock.end();
+      self.emit("warning", addr + " was tried to connect once more");
+      return;
+    }
+    self._clients[addr] = sock;
     sock.on("close", function() {
-      delete self._clients[sock.id];
+      delete self._clients[addr];
     });
     var transport = new self.constructor({
       client: sock,
       seeds: self.seeds,
       dnsSeeds: self.dnsSeeds,
     });
-    self.emit("connection", transport);
+    self.emit("connection", transport, unmap(addr), port);
   });
 
   server.on("error", function(err) {
@@ -155,8 +171,8 @@ Transport.prototype.send = function(data) {
 
 Transport.prototype.broadcast = function(data) {
   if (this._server) {
-    Object.keys(this._clients).forEach(function(id) {
-      this._clients[id].write(data);
+    Object.keys(this._clients).forEach(function(ip) {
+      this._clients[ip].write(data);
     }, this);
   } else {
     throw new Error("Not listening");
@@ -167,8 +183,8 @@ Transport.prototype.close = function() {
   if (this._client) {
     this._client.end();
   } else if (this._server) {
-    Object.keys(this._clients).forEach(function(id) {
-      this._clients[id].end();
+    Object.keys(this._clients).forEach(function(ip) {
+      this._clients[ip].end();
     }, this);
     this._server.close();
   }
diff --git a/tests/run-test-nodes.js b/tests/run-test-nodes.js
index e602716..a00e4d9 100644
--- a/tests/run-test-nodes.js
+++ b/tests/run-test-nodes.js
@@ -11,6 +11,9 @@ var WS_NODE_PATH = path.join(__dirname, "ws-node.js");
 
 function spawn(path) {
   var p = child.spawn("node", [path]);
+  p.stdout.on("data", function(data) {
+    console.log("Info from", path, ":", data.toString().trim());
+  });
   p.stderr.on("data", function(err) {
     console.log("Error from", path, ":", err.toString());
   });