diff --git a/bypass.go b/bypass.go
index 792c33d..5b98cfd 100644
--- a/bypass.go
+++ b/bypass.go
@@ -124,7 +124,7 @@ type Bypass struct {
 	matchers []Matcher
 	reversed bool
 	period   time.Duration // the period for live reloading
-	mux      sync.Mutex
+	mux      sync.RWMutex
 }
 
 // NewBypass creates and initializes a new Bypass using matchers as its match rules.
@@ -160,8 +160,8 @@ func (bp *Bypass) Contains(addr string) bool {
 		}
 	}
 
-	bp.mux.Lock()
-	defer bp.mux.Unlock()
+	bp.mux.RLock()
+	defer bp.mux.RUnlock()
 
 	var matched bool
 	for _, matcher := range bp.matchers {
@@ -179,22 +179,33 @@ func (bp *Bypass) Contains(addr string) bool {
 
 // AddMatchers appends matchers to the bypass matcher list.
 func (bp *Bypass) AddMatchers(matchers ...Matcher) {
+	bp.mux.Lock()
+	defer bp.mux.Unlock()
+
 	bp.matchers = append(bp.matchers, matchers...)
 }
 
 // Matchers return the bypass matcher list.
 func (bp *Bypass) Matchers() []Matcher {
+	bp.mux.RLock()
+	defer bp.mux.RUnlock()
+
 	return bp.matchers
 }
 
 // Reversed reports whether the rules of the bypass are reversed.
 func (bp *Bypass) Reversed() bool {
+	bp.mux.RLock()
+	defer bp.mux.RUnlock()
+
 	return bp.reversed
 }
 
 // Reload parses config from r, then live reloads the bypass.
 func (bp *Bypass) Reload(r io.Reader) error {
 	var matchers []Matcher
+	var period time.Duration
+	var reversed bool
 
 	scanner := bufio.NewScanner(r)
 	for scanner.Scan() {
@@ -217,7 +228,7 @@ func (bp *Bypass) Reload(r io.Reader) error {
 				}
 			}
 			if len(ss) == 2 {
-				bp.period, _ = time.ParseDuration(ss[1])
+				period, _ = time.ParseDuration(ss[1])
 				continue
 			}
 		}
@@ -231,7 +242,7 @@ func (bp *Bypass) Reload(r io.Reader) error {
 				}
 			}
 			if len(ss) == 2 {
-				bp.reversed, _ = strconv.ParseBool(ss[1])
+				reversed, _ = strconv.ParseBool(ss[1])
 				continue
 			}
 		}
@@ -247,19 +258,28 @@ func (bp *Bypass) Reload(r io.Reader) error {
 	defer bp.mux.Unlock()
 
 	bp.matchers = matchers
+	bp.period = period
+	bp.reversed = reversed
 
 	return nil
 }
 
 // Period returns the reload period
 func (bp *Bypass) Period() time.Duration {
+	bp.mux.RLock()
+	defer bp.mux.RUnlock()
+
 	return bp.period
 }
 
 func (bp *Bypass) String() string {
+	bp.mux.RLock()
+	defer bp.mux.RUnlock()
+
 	b := &bytes.Buffer{}
-	fmt.Fprintf(b, "reversed: %v\n", bp.Reversed())
-	for _, m := range bp.Matchers() {
+	fmt.Fprintf(b, "reversed: %v\n", bp.reversed)
+	fmt.Fprintf(b, "reload: %v\n", bp.period)
+	for _, m := range bp.matchers {
 		b.WriteString(m.String())
 		b.WriteByte('\n')
 	}
diff --git a/chain.go b/chain.go
index cf77cf8..9116508 100644
--- a/chain.go
+++ b/chain.go
@@ -38,7 +38,7 @@ func newRoute(nodes ...Node) *Chain {
 }
 
 // Nodes returns the proxy nodes that the chain holds.
-// If a node is a node group, the first node in the group will be returned.
+// The first node in each group will be returned.
 func (c *Chain) Nodes() (nodes []Node) {
 	for _, group := range c.nodeGroups {
 		if ns := group.Nodes(); len(ns) > 0 {
@@ -61,7 +61,7 @@ func (c *Chain) LastNode() Node {
 		return Node{}
 	}
 	group := c.nodeGroups[len(c.nodeGroups)-1]
-	return group.nodes[0].Clone()
+	return group.GetNode(0)
 }
 
 // LastNodeGroup returns the last group of the group list.
@@ -173,7 +173,6 @@ func (c *Chain) resolve(addr string, resolver Resolver, hosts *Hosts) string {
 }
 
 // Conn obtains a handshaked connection to the last node of the chain.
-// If the chain is empty, it returns an ErrEmptyChain error.
 func (c *Chain) Conn(opts ...ChainOption) (conn net.Conn, err error) {
 	options := &ChainOptions{}
 	for _, opt := range opts {
@@ -206,6 +205,7 @@ func (c *Chain) Conn(opts ...ChainOption) (conn net.Conn, err error) {
 }
 
 // getConn obtains a connection to the last node of the chain.
+// It does not handshake with the last node.
 func (c *Chain) getConn() (conn net.Conn, err error) {
 	if c.IsEmpty() {
 		err = ErrEmptyChain
@@ -216,16 +216,16 @@ func (c *Chain) getConn() (conn net.Conn, err error) {
 
 	cn, err := node.Client.Dial(node.Addr, node.DialOptions...)
 	if err != nil {
-		node.MarkDead()
+		node.group.MarkDeadNode(node.ID)
 		return
 	}
 
 	cn, err = node.Client.Handshake(cn, node.HandshakeOptions...)
 	if err != nil {
-		node.MarkDead()
+		node.group.MarkDeadNode(node.ID)
 		return
 	}
-	node.ResetDead()
+	node.group.ResetDeadNode(node.ID)
 
 	preNode := node
 	for _, node := range nodes[1:] {
@@ -233,16 +233,16 @@ func (c *Chain) getConn() (conn net.Conn, err error) {
 		cc, err = preNode.Client.Connect(cn, node.Addr)
 		if err != nil {
 			cn.Close()
-			node.MarkDead()
+			node.group.MarkDeadNode(node.ID)
 			return
 		}
 		cc, err = node.Client.Handshake(cc, node.HandshakeOptions...)
 		if err != nil {
 			cn.Close()
-			node.MarkDead()
+			node.group.MarkDeadNode(node.ID)
 			return
 		}
-		node.ResetDead()
+		node.group.ResetDeadNode(node.ID)
 
 		cn = cc
 		preNode = node
diff --git a/cmd/gost/peer.go b/cmd/gost/peer.go
index 7952ba2..a0e43a7 100644
--- a/cmd/gost/peer.go
+++ b/cmd/gost/peer.go
@@ -60,7 +60,8 @@ func (cfg *peerConfig) Reload(r io.Reader) error {
 			strategy = s
 		}
 	}
-	group.Options = append([]gost.SelectOption{},
+	group.SetSelector(
+		nil,
 		gost.WithFilter(&gost.FailFilter{
 			MaxFails:    cfg.MaxFails,
 			FailTimeout: time.Duration(cfg.FailTimeout) * time.Second,
diff --git a/forward.go b/forward.go
index c901c60..8519c66 100644
--- a/forward.go
+++ b/forward.go
@@ -107,7 +107,7 @@ func (h *tcpDirectForwardHandler) Handle(conn net.Conn) {
 		)
 		if err != nil {
 			log.Logf("[tcp] %s -> %s : %s", conn.RemoteAddr(), node.Addr, err)
-			node.MarkDead()
+			node.group.MarkDeadNode(node.ID)
 		} else {
 			break
 		}
@@ -116,7 +116,7 @@ func (h *tcpDirectForwardHandler) Handle(conn net.Conn) {
 		return
 	}
 
-	node.ResetDead()
+	node.group.ResetDeadNode(node.ID)
 	defer cc.Close()
 
 	log.Logf("[tcp] %s <-> %s", conn.RemoteAddr(), node.Addr)
@@ -191,13 +191,13 @@ func (h *udpDirectForwardHandler) Handle(conn net.Conn) {
 	if h.options.Chain.IsEmpty() {
 		raddr, err := net.ResolveUDPAddr("udp", node.Addr)
 		if err != nil {
-			node.MarkDead()
+			node.group.MarkDeadNode(node.ID)
 			log.Logf("[udp] %s - %s : %s", conn.LocalAddr(), node.Addr, err)
 			return
 		}
 		cc, err = net.DialUDP("udp", nil, raddr)
 		if err != nil {
-			node.MarkDead()
+			node.group.MarkDeadNode(node.ID)
 			log.Logf("[udp] %s - %s : %s", conn.LocalAddr(), node.Addr, err)
 			return
 		}
@@ -212,7 +212,7 @@ func (h *udpDirectForwardHandler) Handle(conn net.Conn) {
 	}
 
 	defer cc.Close()
-	node.ResetDead()
+	node.group.ResetDeadNode(node.ID)
 
 	log.Logf("[udp] %s <-> %s", conn.RemoteAddr(), node.Addr)
 	transport(conn, cc)
@@ -291,7 +291,7 @@ func (h *tcpRemoteForwardHandler) Handle(conn net.Conn) {
 		cc, err = net.DialTimeout("tcp", node.Addr, h.options.Timeout)
 		if err != nil {
 			log.Logf("[rtcp] %s -> %s : %s", conn.LocalAddr(), node.Addr, err)
-			node.MarkDead()
+			node.group.MarkDeadNode(node.ID)
 		} else {
 			break
 		}
@@ -301,7 +301,7 @@ func (h *tcpRemoteForwardHandler) Handle(conn net.Conn) {
 	}
 
 	defer cc.Close()
-	node.ResetDead()
+	node.group.ResetDeadNode(node.ID)
 
 	log.Logf("[rtcp] %s <-> %s", conn.LocalAddr(), node.Addr)
 	transport(cc, conn)
@@ -369,18 +369,18 @@ func (h *udpRemoteForwardHandler) Handle(conn net.Conn) {
 
 	raddr, err := net.ResolveUDPAddr("udp", node.Addr)
 	if err != nil {
-		node.MarkDead()
+		node.group.MarkDeadNode(node.ID)
 		log.Logf("[rudp] %s - %s : %s", conn.RemoteAddr(), node.Addr, err)
 		return
 	}
 	cc, err := net.DialUDP("udp", nil, raddr)
 	if err != nil {
-		node.MarkDead()
+		node.group.MarkDeadNode(node.ID)
 		log.Logf("[rudp] %s - %s : %s", conn.RemoteAddr(), node.Addr, err)
 		return
 	}
 	defer cc.Close()
-	node.ResetDead()
+	node.group.ResetDeadNode(node.ID)
 
 	log.Logf("[rudp] %s <-> %s", conn.RemoteAddr(), node.Addr)
 	transport(conn, cc)
diff --git a/hosts.go b/hosts.go
index de2866f..b7744d5 100644
--- a/hosts.go
+++ b/hosts.go
@@ -5,6 +5,7 @@ import (
 	"io"
 	"net"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/go-log/log"
@@ -25,6 +26,7 @@ type Host struct {
 type Hosts struct {
 	hosts  []Host
 	period time.Duration
+	mux    sync.RWMutex
 }
 
 // NewHosts creates a Hosts with optional list of host
@@ -36,6 +38,9 @@ func NewHosts(hosts ...Host) *Hosts {
 
 // AddHost adds host(s) to the host table.
 func (h *Hosts) AddHost(host ...Host) {
+	h.mux.Lock()
+	defer h.mux.Unlock()
+
 	h.hosts = append(h.hosts, host...)
 }
 
@@ -44,6 +49,10 @@ func (h *Hosts) Lookup(host string) (ip net.IP) {
 	if h == nil {
 		return
 	}
+
+	h.mux.RLock()
+	defer h.mux.RUnlock()
+
 	for _, h := range h.hosts {
 		if h.Hostname == host {
 			ip = h.IP
@@ -64,6 +73,7 @@ func (h *Hosts) Lookup(host string) (ip net.IP) {
 
 // Reload parses config from r, then live reloads the hosts.
 func (h *Hosts) Reload(r io.Reader) error {
+	var period time.Duration
 	var hosts []Host
 
 	scanner := bufio.NewScanner(r)
@@ -89,7 +99,7 @@ func (h *Hosts) Reload(r io.Reader) error {
 
 		// reload option
 		if strings.ToLower(ss[0]) == "reload" {
-			h.period, _ = time.ParseDuration(ss[1])
+			period, _ = time.ParseDuration(ss[1])
 			continue
 		}
 
@@ -110,11 +120,18 @@ func (h *Hosts) Reload(r io.Reader) error {
 		return err
 	}
 
+	h.mux.Lock()
+	h.period = period
 	h.hosts = hosts
+	h.mux.Unlock()
+
 	return nil
 }
 
 // Period returns the reload period
 func (h *Hosts) Period() time.Duration {
+	h.mux.RLock()
+	defer h.mux.RUnlock()
+
 	return h.period
 }
diff --git a/http2.go b/http2.go
index cdd7109..922b02a 100644
--- a/http2.go
+++ b/http2.go
@@ -321,7 +321,7 @@ func (h *http2Handler) roundTrip(w http.ResponseWriter, r *http.Request) {
 
 	u, p, _ := basicProxyAuth(r.Header.Get("Proxy-Authorization"))
 	if Debug && (u != "" || p != "") {
-		log.Logf("[http] %s - %s : Authorization: '%s' '%s'", r.RemoteAddr, target, u, p)
+		log.Logf("[http2] %s - %s : Authorization: '%s' '%s'", r.RemoteAddr, target, u, p)
 	}
 	if !authenticate(u, p, h.options.Users...) {
 		// probing resistance is enabled
diff --git a/node.go b/node.go
index 247dcff..d6c7e7e 100644
--- a/node.go
+++ b/node.go
@@ -5,6 +5,7 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"time"
 )
@@ -88,41 +89,6 @@ func ParseNode(s string) (node Node, err error) {
 	return
 }
 
-// MarkDead marks the node fail status.
-func (node *Node) MarkDead() {
-	atomic.AddUint32(&node.failCount, 1)
-	atomic.StoreInt64(&node.failTime, time.Now().Unix())
-
-	if node.group == nil {
-		return
-	}
-	for i := range node.group.nodes {
-		if node.group.nodes[i].ID == node.ID {
-			atomic.AddUint32(&node.group.nodes[i].failCount, 1)
-			atomic.StoreInt64(&node.group.nodes[i].failTime, time.Now().Unix())
-			break
-		}
-	}
-}
-
-// ResetDead resets the node fail status.
-func (node *Node) ResetDead() {
-	atomic.StoreUint32(&node.failCount, 0)
-	atomic.StoreInt64(&node.failTime, 0)
-
-	if node.group == nil {
-		return
-	}
-
-	for i := range node.group.nodes {
-		if node.group.nodes[i].ID == node.ID {
-			atomic.StoreUint32(&node.group.nodes[i].failCount, 0)
-			atomic.StoreInt64(&node.group.nodes[i].failTime, 0)
-			break
-		}
-	}
-}
-
 // Clone clones the node, it will prevent data race.
 func (node *Node) Clone() Node {
 	return Node{
@@ -167,10 +133,11 @@ func (node *Node) String() string {
 
 // NodeGroup is a group of nodes.
 type NodeGroup struct {
-	ID       int
-	nodes    []Node
-	Options  []SelectOption
-	Selector NodeSelector
+	ID              int
+	nodes           []Node
+	selectorOptions []SelectOption
+	selector        NodeSelector
+	mux             sync.RWMutex
 }
 
 // NewNodeGroup creates a node group
@@ -185,11 +152,21 @@ func (group *NodeGroup) AddNode(node ...Node) {
 	if group == nil {
 		return
 	}
+	group.mux.Lock()
+	defer group.mux.Unlock()
+
 	group.nodes = append(group.nodes, node...)
 }
 
 // SetNodes replaces the group nodes to the specified nodes.
 func (group *NodeGroup) SetNodes(nodes ...Node) {
+	if group == nil {
+		return
+	}
+
+	group.mux.Lock()
+	defer group.mux.Unlock()
+
 	group.nodes = nodes
 }
 
@@ -198,27 +175,100 @@ func (group *NodeGroup) SetSelector(selector NodeSelector, opts ...SelectOption)
 	if group == nil {
 		return
 	}
-	group.Selector = selector
-	group.Options = opts
+	group.mux.Lock()
+	defer group.mux.Unlock()
+
+	group.selector = selector
+	group.selectorOptions = opts
 }
 
-// Nodes returns node list in the group
+// Nodes returns the node list in the group
 func (group *NodeGroup) Nodes() []Node {
 	if group == nil {
 		return nil
 	}
+
+	group.mux.RLock()
+	defer group.mux.RUnlock()
+
 	return group.nodes
 }
 
-// Next selects the next node from group.
+func (group *NodeGroup) copyNodes() []Node {
+	group.mux.RLock()
+	defer group.mux.RUnlock()
+
+	var nodes []Node
+	for i := range group.nodes {
+		nodes = append(nodes, group.nodes[i])
+	}
+	return nodes
+}
+
+// GetNode returns a copy of the node specified by index in the group.
+func (group *NodeGroup) GetNode(i int) Node {
+	group.mux.RLock()
+	defer group.mux.RUnlock()
+
+	if i < 0 || group == nil || len(group.nodes) <= i {
+		return Node{}
+	}
+	return group.nodes[i].Clone()
+}
+
+// MarkDeadNode marks the node with ID nid status to dead.
+func (group *NodeGroup) MarkDeadNode(nid int) {
+	group.mux.RLock()
+	defer group.mux.RUnlock()
+
+	if group == nil || nid <= 0 {
+		return
+	}
+
+	for i := range group.nodes {
+		if group.nodes[i].ID == nid {
+			atomic.AddUint32(&group.nodes[i].failCount, 1)
+			atomic.StoreInt64(&group.nodes[i].failTime, time.Now().Unix())
+			break
+		}
+	}
+}
+
+// ResetDeadNode resets the node with ID nid status.
+func (group *NodeGroup) ResetDeadNode(nid int) {
+	group.mux.RLock()
+	defer group.mux.RUnlock()
+
+	if group == nil || nid <= 0 {
+		return
+	}
+
+	for i := range group.nodes {
+		if group.nodes[i].ID == nid {
+			atomic.StoreUint32(&group.nodes[i].failCount, 0)
+			atomic.StoreInt64(&group.nodes[i].failTime, 0)
+			break
+		}
+	}
+}
+
+// Next selects a node from group.
 // It also selects IP if the IP list exists.
 func (group *NodeGroup) Next() (node Node, err error) {
-	selector := group.Selector
+	if group == nil {
+		return
+	}
+
+	group.mux.RLock()
+	defer group.mux.RUnlock()
+
+	selector := group.selector
 	if selector == nil {
 		selector = &defaultSelector{}
 	}
+
 	// select node from node group
-	node, err = selector.Select(group.Nodes(), group.Options...)
+	node, err = selector.Select(group.nodes, group.selectorOptions...)
 	if err != nil {
 		return
 	}
diff --git a/reload.go b/reload.go
index 5b96d8c..e5ced63 100644
--- a/reload.go
+++ b/reload.go
@@ -26,6 +26,7 @@ func PeriodReload(r Reloader, configFile string) error {
 
 		finfo, err := f.Stat()
 		if err != nil {
+			f.Close()
 			return err
 		}
 		mt := finfo.ModTime()
diff --git a/resolver.go b/resolver.go
index 25cb39b..5d25fc7 100644
--- a/resolver.go
+++ b/resolver.go
@@ -68,6 +68,7 @@ type resolver struct {
 	TTL      time.Duration
 	period   time.Duration
 	domain   string
+	mux      sync.RWMutex
 }
 
 // NewResolver create a new Resolver with the given name servers and resolution timeout.
@@ -78,17 +79,23 @@ func NewResolver(timeout, ttl time.Duration, servers ...NameServer) ReloadResolv
 		TTL:     ttl,
 		mCache:  &sync.Map{},
 	}
-	r.init()
-	return r
-}
 
-func (r *resolver) init() {
 	if r.Timeout <= 0 {
 		r.Timeout = DefaultResolverTimeout
 	}
 	if r.TTL == 0 {
 		r.TTL = DefaultResolverTTL
 	}
+	return r
+}
+
+func (r *resolver) copyServers() []NameServer {
+	var servers []NameServer
+	for i := range r.Servers {
+		servers = append(servers, r.Servers[i])
+	}
+
+	return servers
 }
 
 func (r *resolver) Resolve(host string) (ips []net.IP, err error) {
@@ -96,14 +103,24 @@ func (r *resolver) Resolve(host string) (ips []net.IP, err error) {
 		return
 	}
 
+	var domain string
+	var timeout, ttl time.Duration
+	var servers []NameServer
+
+	r.mux.RLock()
+	domain = r.domain
+	timeout = r.Timeout
+	servers = r.copyServers()
+	r.mux.RUnlock()
+
 	if ip := net.ParseIP(host); ip != nil {
 		return []net.IP{ip}, nil
 	}
 
-	if !strings.Contains(host, ".") && r.domain != "" {
-		host = host + "." + r.domain
+	if !strings.Contains(host, ".") && domain != "" {
+		host = host + "." + domain
 	}
-	ips = r.loadCache(host)
+	ips = r.loadCache(host, ttl)
 	if len(ips) > 0 {
 		if Debug {
 			log.Logf("[resolver] cache hit %s: %v", host, ips)
@@ -111,8 +128,8 @@ func (r *resolver) Resolve(host string) (ips []net.IP, err error) {
 		return
 	}
 
-	for _, ns := range r.Servers {
-		ips, err = r.resolve(ns, host)
+	for _, ns := range servers {
+		ips, err = r.resolve(ns, host, timeout)
 		if err != nil {
 			log.Logf("[resolver] %s via %s : %s", host, ns, err)
 			continue
@@ -130,14 +147,14 @@ func (r *resolver) Resolve(host string) (ips []net.IP, err error) {
 	return
 }
 
-func (r *resolver) resolve(ns NameServer, host string) (ips []net.IP, err error) {
+func (*resolver) resolve(ns NameServer, host string, timeout time.Duration) (ips []net.IP, err error) {
 	addr := ns.Addr
 	if _, port, _ := net.SplitHostPort(addr); port == "" {
 		addr = net.JoinHostPort(addr, "53")
 	}
 
 	client := dns.Client{
-		Timeout: r.Timeout,
+		Timeout: timeout,
 	}
 	switch strings.ToLower(ns.Protocol) {
 	case "tcp":
@@ -171,8 +188,7 @@ func (r *resolver) resolve(ns NameServer, host string) (ips []net.IP, err error)
 	return
 }
 
-func (r *resolver) loadCache(name string) []net.IP {
-	ttl := r.TTL
+func (r *resolver) loadCache(name string, ttl time.Duration) []net.IP {
 	if ttl < 0 {
 		return nil
 	}
@@ -189,8 +205,7 @@ func (r *resolver) loadCache(name string) []net.IP {
 }
 
 func (r *resolver) storeCache(name string, ips []net.IP) {
-	ttl := r.TTL
-	if ttl < 0 || name == "" || len(ips) == 0 {
+	if name == "" || len(ips) == 0 {
 		return
 	}
 	r.mCache.Store(name, &resolverCacheItem{
@@ -200,6 +215,8 @@ func (r *resolver) storeCache(name string, ips []net.IP) {
 }
 
 func (r *resolver) Reload(rd io.Reader) error {
+	var ttl, timeout, period time.Duration
+	var domain string
 	var nss []NameServer
 
 	split := func(line string) []string {
@@ -232,19 +249,19 @@ func (r *resolver) Reload(rd io.Reader) error {
 		switch ss[0] {
 		case "timeout": // timeout option
 			if len(ss) > 1 {
-				r.Timeout, _ = time.ParseDuration(ss[1])
+				timeout, _ = time.ParseDuration(ss[1])
 			}
 		case "ttl": // ttl option
 			if len(ss) > 1 {
-				r.TTL, _ = time.ParseDuration(ss[1])
+				ttl, _ = time.ParseDuration(ss[1])
 			}
 		case "reload": // reload option
 			if len(ss) > 1 {
-				r.period, _ = time.ParseDuration(ss[1])
+				period, _ = time.ParseDuration(ss[1])
 			}
 		case "domain":
 			if len(ss) > 1 {
-				r.domain = ss[1]
+				domain = ss[1]
 			}
 		case "search", "sortlist", "options": // we don't support these features in /etc/resolv.conf
 		case "nameserver": // nameserver option, compatible with /etc/resolv.conf
@@ -276,11 +293,21 @@ func (r *resolver) Reload(rd io.Reader) error {
 		return err
 	}
 
+	r.mux.Lock()
+	r.Timeout = timeout
+	r.TTL = ttl
+	r.domain = domain
+	r.period = period
 	r.Servers = nss
+	r.mux.Unlock()
+
 	return nil
 }
 
 func (r *resolver) Period() time.Duration {
+	r.mux.RLock()
+	defer r.mux.RUnlock()
+
 	return r.period
 }
 
@@ -289,6 +316,9 @@ func (r *resolver) String() string {
 		return ""
 	}
 
+	r.mux.RLock()
+	defer r.mux.RUnlock()
+
 	b := &bytes.Buffer{}
 	fmt.Fprintf(b, "Timeout %v\n", r.Timeout)
 	fmt.Fprintf(b, "TTL %v\n", r.TTL)
diff --git a/selector.go b/selector.go
index cadf799..f83a601 100644
--- a/selector.go
+++ b/selector.go
@@ -94,6 +94,7 @@ type RandomStrategy struct {
 	Seed int64
 	rand *rand.Rand
 	once sync.Once
+	mux  sync.Mutex
 }
 
 // Apply applies the random strategy for the nodes.
@@ -109,7 +110,11 @@ func (s *RandomStrategy) Apply(nodes []Node) Node {
 		return Node{}
 	}
 
-	return nodes[s.rand.Int()%len(nodes)]
+	s.mux.Lock()
+	r := s.rand.Int()
+	s.mux.Unlock()
+
+	return nodes[r%len(nodes)]
 }
 
 func (s *RandomStrategy) String() string {
diff --git a/server.go b/server.go
index a9fbd0e..e4cdfce 100644
--- a/server.go
+++ b/server.go
@@ -72,11 +72,13 @@ func (s *Server) Serve(h Handler, opts ...ServerOption) error {
 		}
 		tempDelay = 0
 
-		if s.options.Bypass.Contains(conn.RemoteAddr().String()) {
-			log.Log("[bypass]", conn.RemoteAddr())
-			conn.Close()
-			continue
-		}
+		/*
+			if s.options.Bypass.Contains(conn.RemoteAddr().String()) {
+				log.Log("[bypass]", conn.RemoteAddr())
+				conn.Close()
+				continue
+			}
+		*/
 
 		go h.Handle(conn)
 	}
@@ -90,12 +92,14 @@ type ServerOptions struct {
 // ServerOption allows a common way to set server options.
 type ServerOption func(opts *ServerOptions)
 
+/*
 // BypassServerOption sets the bypass option of ServerOptions.
 func BypassServerOption(bypass *Bypass) ServerOption {
 	return func(opts *ServerOptions) {
 		opts.Bypass = bypass
 	}
 }
+*/
 
 // Listener is a proxy server listener, just like a net.Listener.
 type Listener interface {