diff --git a/client.js b/client.js
index 464e7bee..af543af7 100644
--- a/client.js
+++ b/client.js
@@ -36,7 +36,7 @@ function Client (peerId, port, torrent, opts) {
   // required
   self._peerId = Buffer.isBuffer(peerId)
     ? peerId
-    : new Buffer(peerId, 'utf8')
+    : new Buffer(peerId, 'hex')
   self._port = port
   self._infoHash = Buffer.isBuffer(torrent.infoHash)
     ? torrent.infoHash
diff --git a/lib/common.js b/lib/common.js
index 727e239c..1e2b7928 100644
--- a/lib/common.js
+++ b/lib/common.js
@@ -4,6 +4,9 @@
 
 var querystring = require('querystring')
 
+exports.IPV4_RE = /^[\d\.]+$/
+exports.IPV6_RE = /^[\da-fA-F:]+$/
+
 exports.NUM_ANNOUNCE_PEERS = 50
 exports.MAX_ANNOUNCE_PEERS = 82
 
@@ -15,7 +18,7 @@ exports.EVENT_IDS = {
   1: 'completed',
   2: 'started',
   3: 'stopped'
-};
+}
 
 function toUInt32 (n) {
   var buf = new Buffer(4)
@@ -24,8 +27,12 @@ function toUInt32 (n) {
 }
 exports.toUInt32 = toUInt32
 
-exports.binaryToUtf8 = function (str) {
-  return new Buffer(str, 'binary').toString('utf8')
+exports.binaryToHex = function (str) {
+  return new Buffer(str, 'binary').toString('hex')
+}
+
+exports.hexToBinary = function (str) {
+  return new Buffer(str, 'hex').toString('binary')
 }
 
 /**
diff --git a/lib/parse_http.js b/lib/parse_http.js
index c6b67d71..fe1c17b2 100644
--- a/lib/parse_http.js
+++ b/lib/parse_http.js
@@ -2,7 +2,7 @@ module.exports = parseHttpRequest
 
 var common = require('./common')
 
-var REMOVE_IPV6_RE = /^::ffff:/
+var REMOVE_IPV4_MAPPED_IPV6_RE = /^::ffff:/
 
 function parseHttpRequest (req, options) {
   var s = req.url.split('?')
@@ -11,48 +11,44 @@ function parseHttpRequest (req, options) {
   if (s[0] === '/announce') {
     params.action = common.ACTIONS.ANNOUNCE
 
-    params.peer_id = typeof params.peer_id === 'string' && common.binaryToUtf8(params.peer_id)
-    params.port = Number(params.port)
+    if (typeof params.info_hash !== 'string' || params.info_hash.length !== 20)
+      throw new Error('invalid info_hash')
+    params.info_hash = common.binaryToHex(params.info_hash)
+    if (typeof params.peer_id !== 'string' || params.peer_id.length !== 20)
+      throw new Error('invalid peer_id')
+    params.peer_id = common.binaryToHex(params.peer_id)
 
-    if (typeof params.info_hash !== 'string') throw new Error('invalid info_hash')
-    if (params.info_hash.length !== 20) throw new Error('invalid info_hash length')
-    if (typeof params.peer_id !== 'string') throw new Error('invalid peer_id')
-    if (params.peer_id.length !== 20) throw new Error('invalid peer_id length')
+    params.port = Number(params.port)
     if (!params.port) throw new Error('invalid port')
 
     params.left = Number(params.left)
     params.compact = Number(params.compact)
-
-    params.ip = options.trustProxy
-      ? req.headers['x-forwarded-for'] || req.connection.remoteAddress
-      : req.connection.remoteAddress.replace(REMOVE_IPV6_RE, '') // force ipv4
-    params.addr = params.ip + ':' + params.port // TODO: ipv6 brackets?
-
     params.numwant = Math.min(
       Number(params.numwant) || common.NUM_ANNOUNCE_PEERS,
       common.MAX_ANNOUNCE_PEERS
     )
 
-    return params
+    params.ip = options.trustProxy
+      ? req.headers['x-forwarded-for'] || req.connection.remoteAddress
+      : req.connection.remoteAddress.replace(REMOVE_IPV4_MAPPED_IPV6_RE, '') // force ipv4
+    params.addr = (common.IPV6_RE.test(params.ip) ? '[' + params.ip + ']' : params.ip) + ':' + params.port
+
   } else if (s[0] === '/scrape') { // unofficial scrape message
     params.action = common.ACTIONS.SCRAPE
-
-    if (typeof params.info_hash === 'string') {
+    if (typeof params.info_hash === 'string')
       params.info_hash = [ params.info_hash ]
-    }
-
-    if (params.info_hash) {
-      if (!Array.isArray(params.info_hash)) throw new Error('invalid info_hash array')
 
-      params.info_hash.forEach(function (infoHash) {
-        if (infoHash.length !== 20) {
+    if (Array.isArray(params.info_hash)) {
+      params.info_hash = params.info_hash.map(function (binaryInfoHash) {
+        if (typeof binaryInfoHash !== 'string' || binaryInfoHash.length !== 20)
           throw new Error('invalid info_hash')
-        }
+        return common.binaryToHex(binaryInfoHash)
       })
     }
 
-    return params
   } else {
-    return null
+    throw new Error('Invalid action in HTTP request: ' + params.action)
   }
+
+  return params
 }
diff --git a/lib/parse_udp.js b/lib/parse_udp.js
index 2122d965..0e7a0089 100644
--- a/lib/parse_udp.js
+++ b/lib/parse_udp.js
@@ -5,13 +5,11 @@ var ipLib = require('ip')
 var common = require('./common')
 
 function parseUdpRequest (msg, rinfo) {
-  if (msg.length < 16) {
+  if (msg.length < 16)
     throw new Error('received packet is too short')
-  }
 
-  if (rinfo.family !== 'IPv4') {
+  if (rinfo.family !== 'IPv4')
     throw new Error('udp tracker does not support IPv6')
-  }
 
   var params = {
     connectionId: msg.slice(0, 8), // 64-bit
@@ -20,41 +18,46 @@ function parseUdpRequest (msg, rinfo) {
   }
 
   // TODO: randomize
-  if (!bufferEqual(params.connectionId, common.CONNECTION_ID)) {
+  if (!bufferEqual(params.connectionId, common.CONNECTION_ID))
     throw new Error('received packet with invalid connection id')
-  }
 
   if (params.action === common.ACTIONS.CONNECT) {
     // No further params
+
   } else if (params.action === common.ACTIONS.ANNOUNCE) {
-    params.info_hash = msg.slice(16, 36).toString('binary') // 20 bytes
-    params.peer_id = msg.slice(36, 56).toString('utf8') // 20 bytes
+    params.info_hash = msg.slice(16, 36).toString('hex') // 20 bytes
+    params.peer_id = msg.slice(36, 56).toString('hex') // 20 bytes
     params.downloaded = fromUInt64(msg.slice(56, 64)) // TODO: track this?
     params.left = fromUInt64(msg.slice(64, 72))
     params.uploaded = fromUInt64(msg.slice(72, 80)) // TODO: track this?
-    params.event = msg.readUInt32BE(80)
-    params.event = common.EVENT_IDS[params.event]
+
+    params.event = common.EVENT_IDS[msg.readUInt32BE(80)]
     if (!params.event) throw new Error('invalid event') // early return
-    params.ip = msg.readUInt32BE(84) // optional
-    params.ip = params.ip ?
-      ipLib.toString(params.ip) :
-      rinfo.address
+
+    var ip = msg.readUInt32BE(84) // optional
+    params.ip = ip
+      ? ipLib.toString(ip)
+      : rinfo.address
+
     params.key = msg.readUInt32BE(88) // TODO: what is this for?
-    params.numwant = msg.readUInt32BE(92) // optional
+
     // never send more than MAX_ANNOUNCE_PEERS or else the UDP packet will get bigger than
     // 512 bytes which is not safe
-    params.numwant = Math.min(params.numwant || common.NUM_ANNOUNCE_PEERS, common.MAX_ANNOUNCE_PEERS)
+    params.numwant = Math.min(
+      msg.readUInt32BE(92) || common.NUM_ANNOUNCE_PEERS, // optional
+      common.MAX_ANNOUNCE_PEERS
+    )
+
     params.port = msg.readUInt16BE(96) || rinfo.port // optional
     params.addr = params.ip + ':' + params.port // TODO: ipv6 brackets
     params.compact = 1 // udp is always compact
 
   } else if (params.action === common.ACTIONS.SCRAPE) { // scrape message
-    params.info_hash = msg.slice(16, 36).toString('binary') // 20 bytes
-
     // TODO: support multiple info_hash scrape
-    if (msg.length > 36) {
-      throw new Error('multiple info_hash scrape not supported')
-    }
+    if (msg.length > 36) throw new Error('multiple info_hash scrape not supported')
+
+    params.info_hash = [ msg.slice(16, 36).toString('hex') ] // 20 bytes
+
   } else {
     throw new Error('Invalid action in UDP packet: ' + params.action)
   }
diff --git a/server.js b/server.js
index 5b31b93d..ee3cccd9 100644
--- a/server.js
+++ b/server.js
@@ -94,7 +94,10 @@ Server.prototype.listen = function (port, onlistening) {
   function onPort (err, port) {
     if (err) return self.emit('error', err)
     self.port = port
-    self._httpServer && self._httpServer.listen(port.http || port)
+    // ATTENTION:
+    // binding to :: only receives IPv4 connections if the bindv6only
+    // sysctl is set 0, which is the default on many operating systems.
+    self._httpServer && self._httpServer.listen(port.http || port, '::')
     self._udpServer && self._udpServer.bind(port.udp || port)
   }
 
@@ -115,13 +118,11 @@ Server.prototype.close = function (cb) {
   }
 }
 
-Server.prototype.getSwarm = function (binaryInfoHash) {
+Server.prototype.getSwarm = function (infoHash) {
   var self = this
-  if (Buffer.isBuffer(binaryInfoHash)) binaryInfoHash = binaryInfoHash.toString('binary')
-  var swarm = self.torrents[binaryInfoHash]
-  if (!swarm) {
-    swarm = self.torrents[binaryInfoHash] = new Swarm(binaryInfoHash, this)
-  }
+  if (Buffer.isBuffer(infoHash)) infoHash = infoHash.toString('hex')
+  var swarm = self.torrents[infoHash]
+  if (!swarm) swarm = self.torrents[infoHash] = new Swarm(infoHash, this)
   return swarm
 }
 
@@ -130,9 +131,7 @@ Server.prototype._onHttpRequest = function (req, res) {
 
   var params
   try {
-    params = parseHttpRequest(req, {
-      trustProxy: self._trustProxy
-    })
+    params = parseHttpRequest(req, { trustProxy: self._trustProxy })
   } catch (err) {
     debug('sent error %s', err.message)
     res.end(bencode.encode({
@@ -142,7 +141,7 @@ Server.prototype._onHttpRequest = function (req, res) {
     // even though it's an error for the client, it's just a warning for the server.
     // don't crash the server because a client sent bad data :)
     self.emit('warning', err)
-    
+
     return
   }
 
@@ -212,11 +211,23 @@ Server.prototype._onAnnounce = function (params, cb) {
     if (response) {
       if (!response.action) response.action = common.ACTIONS.ANNOUNCE
       if (!response.intervalMs) response.intervalMs = self._intervalMs
+      
       if (params.compact === 1) {
-        response.peers = string2compact(response.peers.map(function (peer) {
-          return peer.ip + ':' + peer.port // TODO: ipv6 brackets
+        var peers = response.peers
+        // Find IPv4 peers
+        response.peers = string2compact(peers.filter(function (peer) {
+          return common.IPV4_RE.test(peer.ip)
+        }).map(function (peer) {
+          return peer.ip + ':' + peer.port
+        }))
+        // Find IPv6 peers
+        response.peers6 = string2compact(peers.filter(function (peer) {
+          return common.IPV6_RE.test(peer.ip)
+        }).map(function (peer) {
+          return '[' + peer.ip + ']:' + peer.port
         }))
       }
+      // IPv6 peers are not separate for non-compact responses
     }
     cb(err, response)
   })
@@ -225,28 +236,12 @@ Server.prototype._onAnnounce = function (params, cb) {
 Server.prototype._onScrape = function (params, cb) {
   var self = this
 
-  if (typeof params.info_hash === 'string') {
-    params.info_hash = [ params.info_hash ]
-  } else if (params.info_hash == null) {
+  if (params.info_hash == null) {
     // if info_hash param is omitted, stats for all torrents are returned
     // TODO: make this configurable!
     params.info_hash = Object.keys(self.torrents)
   }
 
-  if (!Array.isArray(params.info_hash)) {
-    var err = new Error('invalid info_hash')
-    self.emit('warning', err)
-    return cb(err)
-  }
-
-  var response = {
-    action: common.ACTIONS.SCRAPE,
-    files: {},
-    flags: {
-      min_request_interval: self._intervalMs
-    }
-  }
-
   series(params.info_hash.map(function (infoHash) {
     var swarm = self.getSwarm(infoHash)
     return function (cb) {
@@ -261,8 +256,14 @@ Server.prototype._onScrape = function (params, cb) {
   }), function (err, results) {
     if (err) return cb(err)
 
+    var response = {
+      action: common.ACTIONS.SCRAPE,
+      files: {},
+      flags: { min_request_interval: self._intervalMs }
+    }
+
     results.forEach(function (result) {
-      response.files[result.infoHash] = {
+      response.files[common.hexToBinary(result.infoHash)] = {
         complete: result.complete,
         incomplete: result.incomplete,
         downloaded: result.complete // TODO: this only provides a lower-bound
@@ -273,7 +274,6 @@ Server.prototype._onScrape = function (params, cb) {
   })
 }
 
-
 function makeUdpPacket (params) {
   switch (params.action) {
     case common.ACTIONS.CONNECT:
diff --git a/test/server.js b/test/server.js
index f6ddd8dd..da0a6e70 100644
--- a/test/server.js
+++ b/test/server.js
@@ -2,16 +2,19 @@ var Client = require('../')
 var Server = require('../').Server
 var test = require('tape')
 
-var infoHash = new Buffer('4cb67059ed6bd08362da625b3ae77f6f4a075705', 'hex')
-var peerId = '01234567890123456789'
-var peerId2 = '12345678901234567890'
+var infoHash = '4cb67059ed6bd08362da625b3ae77f6f4a075705'
+var peerId = new Buffer('01234567890123456789')
+var peerId2 = new Buffer('12345678901234567890')
 var torrentLength = 50000
 
-function serverTest (t, serverType) {
+function serverTest (t, serverType, serverFamily) {
   t.plan(26)
 
   var opts = serverType === 'http' ? { udp: false } : { http: false }
   var server = new Server(opts)
+  var serverAddr = serverFamily === 'inet6' ? '[::1]' : '127.0.0.1'
+  var clientAddr = serverFamily === 'inet6' ? '[::1]' : '127.0.0.1'
+  var clientIp = serverFamily === 'inet6' ? '::1' : '127.0.0.1'
 
   server.on('error', function (err) {
     t.fail(err.message)
@@ -26,7 +29,7 @@ function serverTest (t, serverType) {
   })
 
   server.listen(function (port) {
-    var announceUrl = serverType + '://127.0.0.1:' + port + '/announce'
+    var announceUrl = serverType + '://' + serverAddr + ':' + port + '/announce'
 
     var client = new Client(peerId, 6881, {
       infoHash: infoHash,
@@ -49,10 +52,10 @@ function serverTest (t, serverType) {
       t.equal(server.getSwarm(infoHash).complete, 0)
       t.equal(server.getSwarm(infoHash).incomplete, 1)
       t.equal(Object.keys(server.getSwarm(infoHash).peers).length, 1)
-      t.deepEqual(server.getSwarm(infoHash).peers['127.0.0.1:6881'], {
-        ip: '127.0.0.1',
+      t.deepEqual(server.getSwarm(infoHash).peers[clientAddr + ':6881'], {
+        ip: clientIp,
         port: 6881,
-        peerId: peerId
+        peerId: peerId.toString('hex')
       })
 
       client.complete()
@@ -83,7 +86,7 @@ function serverTest (t, serverType) {
           })
 
           client2.once('peer', function (addr) {
-            t.equal(addr, '127.0.0.1:6881')
+            t.equal(addr, clientAddr + ':6881')
 
             client2.stop()
             client2.once('update', function (data) {
@@ -109,10 +112,14 @@ function serverTest (t, serverType) {
   })
 }
 
-test('http server', function (t) {
-  serverTest(t, 'http')
+test('http ipv4 server', function (t) {
+  serverTest(t, 'http', 'inet')
+})
+
+test('http ipv6 server', function (t) {
+  serverTest(t, 'http', 'inet6')
 })
 
 test('udp server', function (t) {
-  serverTest(t, 'udp')
+  serverTest(t, 'udp', 'inet')
 })