diff --git a/ergonomadic.go b/ergonomadic.go
index dbd45ddb..3d107a7c 100644
--- a/ergonomadic.go
+++ b/ergonomadic.go
@@ -12,6 +12,7 @@ import (
 func main() {
 	conf := flag.String("conf", "ergonomadic.conf", "ergonomadic config file")
 	initdb := flag.Bool("initdb", false, "initialize database")
+	upgradedb := flag.Bool("upgradedb", false, "update database")
 	passwd := flag.String("genpasswd", "", "bcrypt a password")
 	flag.Parse()
 
@@ -35,7 +36,13 @@ func main() {
 
 	if *initdb {
 		irc.InitDB(config.Server.Database)
-		log.Println("database initialized: " + config.Server.Database)
+		log.Println("database initialized: ", config.Server.Database)
+		return
+	}
+
+	if *upgradedb {
+		irc.UpgradeDB(config.Server.Database)
+		log.Println("database upgraded: ", config.Server.Database)
 		return
 	}
 
@@ -45,5 +52,8 @@ func main() {
 	irc.DEBUG_CHANNEL = config.Debug.Channel
 	irc.DEBUG_SERVER = config.Debug.Server
 
-	irc.NewServer(config).Run()
+	server := irc.NewServer(config)
+	log.Println(irc.SEM_VER, "running")
+	defer log.Println(irc.SEM_VER, "exiting")
+	server.Run()
 }
diff --git a/irc/channel.go b/irc/channel.go
index d7fa7371..41f7f9a8 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -8,7 +8,7 @@ import (
 
 type Channel struct {
 	flags     ChannelModeSet
-	lists     map[ChannelMode][]UserMask
+	lists     map[ChannelMode]*UserMaskSet
 	key       string
 	members   MemberSet
 	name      string
@@ -26,10 +26,10 @@ func IsChannel(target string) bool {
 func NewChannel(s *Server, name string) *Channel {
 	channel := &Channel{
 		flags: make(ChannelModeSet),
-		lists: map[ChannelMode][]UserMask{
-			BanMask:    []UserMask{},
-			ExceptMask: []UserMask{},
-			InviteMask: []UserMask{},
+		lists: map[ChannelMode]*UserMaskSet{
+			BanMask:    NewUserMaskSet(),
+			ExceptMask: NewUserMaskSet(),
+			InviteMask: NewUserMaskSet(),
 		},
 		members: make(MemberSet),
 		name:    strings.ToLower(name),
@@ -151,6 +151,19 @@ func (channel *Channel) Join(client *Client, key string) {
 		return
 	}
 
+	isInvited := channel.lists[InviteMask].Match(client.UserHost())
+	if channel.flags[InviteOnly] && !isInvited {
+		client.ErrInviteOnlyChan(channel)
+		return
+	}
+
+	if channel.lists[BanMask].Match(client.UserHost()) &&
+		!isInvited &&
+		!channel.lists[ExceptMask].Match(client.UserHost()) {
+		client.ErrBannedFromChan(channel)
+		return
+	}
+
 	client.channels.Add(channel)
 	channel.members.Add(client)
 	if !channel.flags[Persistent] && (len(channel.members) == 1) {
@@ -213,7 +226,7 @@ func (channel *Channel) SetTopic(client *Client, topic string) {
 	}
 
 	if err := channel.Persist(); err != nil {
-		log.Println(err)
+		log.Println("Channel.Persist:", channel, err)
 	}
 }
 
@@ -310,17 +323,48 @@ func (channel *Channel) applyModeMember(client *Client, mode ChannelMode,
 	return false
 }
 
+func (channel *Channel) ShowMaskList(client *Client, mode ChannelMode) {
+	for lmask := range channel.lists[mode].masks {
+		client.RplMaskList(mode, channel, lmask)
+	}
+	client.RplEndOfMaskList(mode, channel)
+}
+
+func (channel *Channel) applyModeMask(client *Client, mode ChannelMode, op ModeOp,
+	mask string) bool {
+	list := channel.lists[mode]
+	if list == nil {
+		// This should never happen, but better safe than panicky.
+		return false
+	}
+
+	if (op == List) || (mask == "") {
+		channel.ShowMaskList(client, mode)
+		return false
+	}
+
+	if !channel.ClientIsOperator(client) {
+		client.ErrChanOPrivIsNeeded(channel)
+		return false
+	}
+
+	if op == Add {
+		return list.Add(mask)
+	}
+
+	if op == Remove {
+		return list.Remove(mask)
+	}
+
+	return false
+}
+
 func (channel *Channel) applyMode(client *Client, change *ChannelModeChange) bool {
 	switch change.mode {
 	case BanMask, ExceptMask, InviteMask:
-		// TODO add/remove
+		return channel.applyModeMask(client, change.mode, change.op, change.arg)
 
-		for _, mask := range channel.lists[change.mode] {
-			client.RplMaskList(change.mode, channel, mask)
-		}
-		client.RplEndOfMaskList(change.mode, channel)
-
-	case Moderated, NoOutside, OpOnlyTopic, Persistent, Private:
+	case InviteOnly, Moderated, NoOutside, OpOnlyTopic, Persistent, Private:
 		return channel.applyModeFlag(client, change.mode, change.op)
 
 	case Key:
@@ -390,7 +434,7 @@ func (channel *Channel) Mode(client *Client, changes ChannelModeChanges) {
 		}
 
 		if err := channel.Persist(); err != nil {
-			log.Println(err)
+			log.Println("Channel.Persist:", channel, err)
 		}
 	}
 }
@@ -399,10 +443,12 @@ func (channel *Channel) Persist() (err error) {
 	if channel.flags[Persistent] {
 		_, err = channel.server.db.Exec(`
             INSERT OR REPLACE INTO channel
-              (name, flags, key, topic, user_limit)
-              VALUES (?, ?, ?, ?, ?)`,
+              (name, flags, key, topic, user_limit, ban_list, except_list,
+               invite_list)
+              VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
 			channel.name, channel.flags.String(), channel.key, channel.topic,
-			channel.userLimit)
+			channel.userLimit, channel.lists[BanMask].String(),
+			channel.lists[ExceptMask].String(), channel.lists[InviteMask].String())
 	} else {
 		_, err = channel.server.db.Exec(`
             DELETE FROM channel WHERE name = ?`, channel.name)
@@ -464,6 +510,13 @@ func (channel *Channel) Invite(invitee *Client, inviter *Client) {
 		return
 	}
 
+	if channel.flags[InviteOnly] {
+		channel.lists[InviteMask].Add(invitee.UserHost())
+		if err := channel.Persist(); err != nil {
+			log.Println("Channel.Persist:", channel, err)
+		}
+	}
+
 	inviter.RplInviting(invitee, channel.name)
 	invitee.Reply(RplInviteMsg(inviter, invitee, channel.name))
 	if invitee.flags[Away] {
diff --git a/irc/client.go b/irc/client.go
index ff306f34..2adb4309 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -229,6 +229,7 @@ func (client *Client) ChangeNickname(nickname string) {
 	// Make reply before changing nick to capture original source id.
 	reply := RplNick(client, nickname)
 	client.server.clients.Remove(client)
+	client.server.whoWas.Append(client)
 	client.nick = nickname
 	client.server.clients.Add(client)
 	for friend := range client.Friends() {
@@ -249,8 +250,8 @@ func (client *Client) Quit(message string) {
 	}
 
 	client.Reply(RplError("connection closed"))
-
 	client.hasQuit = true
+	client.server.whoWas.Append(client)
 	friends := client.Friends()
 	friends.Remove(client)
 	client.destroy()
diff --git a/irc/client_lookup_set.go b/irc/client_lookup_set.go
new file mode 100644
index 00000000..261461d9
--- /dev/null
+++ b/irc/client_lookup_set.go
@@ -0,0 +1,272 @@
+package irc
+
+import (
+	"database/sql"
+	"errors"
+	"log"
+	"regexp"
+	"strings"
+)
+
+var (
+	ErrNickMissing      = errors.New("nick missing")
+	ErrNicknameInUse    = errors.New("nickname in use")
+	ErrNicknameMismatch = errors.New("nickname mismatch")
+	wildMaskExpr        = regexp.MustCompile(`\*|\?`)
+	likeQuoter          = strings.NewReplacer(
+		`\`, `\\`,
+		`%`, `\%`,
+		`_`, `\_`,
+		`*`, `%`,
+		`?`, `_`)
+)
+
+func HasWildcards(mask string) bool {
+	return wildMaskExpr.MatchString(mask)
+}
+
+func ExpandUserHost(userhost string) (expanded string) {
+	expanded = userhost
+	// fill in missing wildcards for nicks
+	if !strings.Contains(expanded, "!") {
+		expanded += "!*"
+	}
+	if !strings.Contains(expanded, "@") {
+		expanded += "@*"
+	}
+	return
+}
+
+func QuoteLike(userhost string) string {
+	return likeQuoter.Replace(userhost)
+}
+
+type ClientLookupSet struct {
+	byNick map[string]*Client
+	db     *ClientDB
+}
+
+func NewClientLookupSet() *ClientLookupSet {
+	return &ClientLookupSet{
+		byNick: make(map[string]*Client),
+		db:     NewClientDB(),
+	}
+}
+
+func (clients *ClientLookupSet) Get(nick string) *Client {
+	return clients.byNick[strings.ToLower(nick)]
+}
+
+func (clients *ClientLookupSet) Add(client *Client) error {
+	if !client.HasNick() {
+		return ErrNickMissing
+	}
+	if clients.Get(client.nick) != nil {
+		return ErrNicknameInUse
+	}
+	clients.byNick[strings.ToLower(client.nick)] = client
+	clients.db.Add(client)
+	return nil
+}
+
+func (clients *ClientLookupSet) Remove(client *Client) error {
+	if !client.HasNick() {
+		return ErrNickMissing
+	}
+	if clients.Get(client.nick) != client {
+		return ErrNicknameMismatch
+	}
+	delete(clients.byNick, strings.ToLower(client.nick))
+	clients.db.Remove(client)
+	return nil
+}
+
+func (clients *ClientLookupSet) FindAll(userhost string) (set ClientSet) {
+	userhost = ExpandUserHost(userhost)
+	set = make(ClientSet)
+	rows, err := clients.db.db.Query(
+		`SELECT nickname FROM client WHERE userhost LIKE ? ESCAPE '\'`,
+		QuoteLike(userhost))
+	if err != nil {
+		if DEBUG_SERVER {
+			log.Println("ClientLookupSet.FindAll.Query:", err)
+		}
+		return
+	}
+	for rows.Next() {
+		var nickname string
+		err := rows.Scan(&nickname)
+		if err != nil {
+			if DEBUG_SERVER {
+				log.Println("ClientLookupSet.FindAll.Scan:", err)
+			}
+			return
+		}
+		client := clients.Get(nickname)
+		if client == nil {
+			if DEBUG_SERVER {
+				log.Println("ClientLookupSet.FindAll: missing client:", nickname)
+			}
+			continue
+		}
+		set.Add(client)
+	}
+	return
+}
+
+func (clients *ClientLookupSet) Find(userhost string) *Client {
+	userhost = ExpandUserHost(userhost)
+	row := clients.db.db.QueryRow(
+		`SELECT nickname FROM client WHERE userhost LIKE ? ESCAPE '\' LIMIT 1`,
+		QuoteLike(userhost))
+	var nickname string
+	err := row.Scan(&nickname)
+	if err != nil {
+		if DEBUG_SERVER {
+			log.Println("ClientLookupSet.Find:", err)
+		}
+		return nil
+	}
+	return clients.Get(nickname)
+}
+
+//
+// client db
+//
+
+type ClientDB struct {
+	db *sql.DB
+}
+
+func NewClientDB() *ClientDB {
+	db := &ClientDB{
+		db: OpenDB(":memory:"),
+	}
+	stmts := []string{
+		`CREATE TABLE client (
+          nickname TEXT NOT NULL COLLATE NOCASE UNIQUE,
+          userhost TEXT NOT NULL COLLATE NOCASE,
+          UNIQUE (nickname, userhost) ON CONFLICT REPLACE)`,
+		`CREATE UNIQUE INDEX idx_nick ON client (nickname COLLATE NOCASE)`,
+		`CREATE UNIQUE INDEX idx_uh ON client (userhost COLLATE NOCASE)`,
+	}
+	for _, stmt := range stmts {
+		_, err := db.db.Exec(stmt)
+		if err != nil {
+			log.Fatal("NewClientDB: ", stmt, err)
+		}
+	}
+	return db
+}
+
+func (db *ClientDB) Add(client *Client) {
+	_, err := db.db.Exec(`INSERT INTO client (nickname, userhost) VALUES (?, ?)`,
+		client.Nick(), client.UserHost())
+	if err != nil {
+		if DEBUG_SERVER {
+			log.Println("ClientDB.Add:", err)
+		}
+	}
+}
+
+func (db *ClientDB) Remove(client *Client) {
+	_, err := db.db.Exec(`DELETE FROM client WHERE nickname = ?`,
+		client.Nick())
+	if err != nil {
+		if DEBUG_SERVER {
+			log.Println("ClientDB.Remove:", err)
+		}
+	}
+}
+
+//
+// usermask to regexp
+//
+
+type UserMaskSet struct {
+	masks  map[string]bool
+	regexp *regexp.Regexp
+}
+
+func NewUserMaskSet() *UserMaskSet {
+	return &UserMaskSet{
+		masks: make(map[string]bool),
+	}
+}
+
+func (set *UserMaskSet) Add(mask string) bool {
+	if set.masks[mask] {
+		return false
+	}
+	set.masks[mask] = true
+	set.setRegexp()
+	return true
+}
+
+func (set *UserMaskSet) AddAll(masks []string) (added bool) {
+	for _, mask := range masks {
+		if !added && !set.masks[mask] {
+			added = true
+		}
+		set.masks[mask] = true
+	}
+	set.setRegexp()
+	return
+}
+
+func (set *UserMaskSet) Remove(mask string) bool {
+	if !set.masks[mask] {
+		return false
+	}
+	delete(set.masks, mask)
+	set.setRegexp()
+	return true
+}
+
+func (set *UserMaskSet) Match(userhost string) bool {
+	if set.regexp == nil {
+		return false
+	}
+	return set.regexp.MatchString(userhost)
+}
+
+func (set *UserMaskSet) String() string {
+	masks := make([]string, len(set.masks))
+	index := 0
+	for mask := range set.masks {
+		masks[index] = mask
+		index += 1
+	}
+	return strings.Join(masks, " ")
+}
+
+// Generate a regular expression from the set of user mask
+// strings. Masks are split at the two types of wildcards, `*` and
+// `?`. All the pieces are meta-escaped. `*` is replaced with `.*`,
+// the regexp equivalent. Likewise, `?` is replaced with `.`. The
+// parts are re-joined and finally all masks are joined into a big
+// or-expression.
+func (set *UserMaskSet) setRegexp() {
+	if len(set.masks) == 0 {
+		set.regexp = nil
+		return
+	}
+
+	maskExprs := make([]string, len(set.masks))
+	index := 0
+	for mask := range set.masks {
+		manyParts := strings.Split(mask, "*")
+		manyExprs := make([]string, len(manyParts))
+		for mindex, manyPart := range manyParts {
+			oneParts := strings.Split(manyPart, "?")
+			oneExprs := make([]string, len(oneParts))
+			for oindex, onePart := range oneParts {
+				oneExprs[oindex] = regexp.QuoteMeta(onePart)
+			}
+			manyExprs[mindex] = strings.Join(oneExprs, ".")
+		}
+		maskExprs[index] = strings.Join(manyExprs, ".*")
+	}
+	expr := "^" + strings.Join(maskExprs, "|") + "$"
+	set.regexp, _ = regexp.Compile(expr)
+}
diff --git a/irc/commands.go b/irc/commands.go
index e7d36130..976d8987 100644
--- a/irc/commands.go
+++ b/irc/commands.go
@@ -54,6 +54,7 @@ var (
 		VERSION: NewVersionCommand,
 		WHO:     NewWhoCommand,
 		WHOIS:   NewWhoisCommand,
+		WHOWAS:  NewWhoWasCommand,
 	}
 )
 
@@ -656,7 +657,7 @@ func (msg *WhoisCommand) String() string {
 
 type WhoCommand struct {
 	BaseCommand
-	mask         Mask
+	mask         string
 	operatorOnly bool
 }
 
@@ -665,7 +666,7 @@ func NewWhoCommand(args []string) (editableCommand, error) {
 	cmd := &WhoCommand{}
 
 	if len(args) > 0 {
-		cmd.mask = Mask(args[0])
+		cmd.mask = args[0]
 	}
 
 	if (len(args) > 1) && (args[1] == "o") {
@@ -982,3 +983,26 @@ func NewKillCommand(args []string) (editableCommand, error) {
 		comment:  args[1],
 	}, nil
 }
+
+type WhoWasCommand struct {
+	BaseCommand
+	nicknames []string
+	count     int64
+	target    string
+}
+
+func NewWhoWasCommand(args []string) (editableCommand, error) {
+	if len(args) < 1 {
+		return nil, NotEnoughArgsError
+	}
+	cmd := &WhoWasCommand{
+		nicknames: strings.Split(args[0], ","),
+	}
+	if len(args) > 1 {
+		cmd.count, _ = strconv.ParseInt(args[1], 10, 64)
+	}
+	if len(args) > 2 {
+		cmd.target = args[2]
+	}
+	return cmd, nil
+}
diff --git a/irc/constants.go b/irc/constants.go
index 2a766927..63368b63 100644
--- a/irc/constants.go
+++ b/irc/constants.go
@@ -61,6 +61,7 @@ const (
 	VERSION StringCode = "VERSION"
 	WHO     StringCode = "WHO"
 	WHOIS   StringCode = "WHOIS"
+	WHOWAS  StringCode = "WHOWAS"
 
 	// numeric codes
 	RPL_WELCOME           NumericCode = 1
diff --git a/irc/database.go b/irc/database.go
index c7f9264a..2a482ecf 100644
--- a/irc/database.go
+++ b/irc/database.go
@@ -2,6 +2,7 @@ package irc
 
 import (
 	"database/sql"
+	"fmt"
 	_ "github.com/mattn/go-sqlite3"
 	"log"
 	"os"
@@ -14,15 +15,30 @@ func InitDB(path string) {
 	_, err := db.Exec(`
         CREATE TABLE channel (
           name TEXT NOT NULL UNIQUE,
-          flags TEXT NOT NULL,
-          key TEXT NOT NULL,
-          topic TEXT NOT NULL,
-          user_limit INTEGER DEFAULT 0)`)
+          flags TEXT DEFAULT '',
+          key TEXT DEFAULT '',
+          topic TEXT DEFAULT '',
+          user_limit INTEGER DEFAULT 0,
+          ban_list TEXT DEFAULT '',
+          except_list TEXT DEFAULT '',
+          invite_list TEXT DEFAULT '')`)
 	if err != nil {
 		log.Fatal("initdb error: ", err)
 	}
 }
 
+func UpgradeDB(path string) {
+	db := OpenDB(path)
+	alter := `ALTER TABLE channel ADD COLUMN %s TEXT DEFAULT ''`
+	cols := []string{"ban_list", "except_list", "invite_list"}
+	for _, col := range cols {
+		_, err := db.Exec(fmt.Sprintf(alter, col))
+		if err != nil {
+			log.Fatal("updatedb error: ", err)
+		}
+	}
+}
+
 func OpenDB(path string) *sql.DB {
 	db, err := sql.Open("sqlite3", path)
 	if err != nil {
diff --git a/irc/reply.go b/irc/reply.go
index 4510f76e..72002f93 100644
--- a/irc/reply.go
+++ b/irc/reply.go
@@ -200,6 +200,16 @@ func (target *Client) RplYoureOper() {
 		":You are now an IRC operator")
 }
 
+func (target *Client) RplWhois(client *Client) {
+	target.RplWhoisUser(client)
+	if client.flags[Operator] {
+		target.RplWhoisOperator(client)
+	}
+	target.RplWhoisIdle(client)
+	target.RplWhoisChannels(client)
+	target.RplEndOfWhois()
+}
+
 func (target *Client) RplWhoisUser(client *Client) {
 	target.NumericReply(RPL_WHOISUSER,
 		"%s %s %s * :%s", client.Nick(), client.username, client.hostname,
@@ -270,7 +280,7 @@ func (target *Client) RplEndOfWho(name string) {
 		"%s :End of WHO list", name)
 }
 
-func (target *Client) RplMaskList(mode ChannelMode, channel *Channel, mask UserMask) {
+func (target *Client) RplMaskList(mode ChannelMode, channel *Channel, mask string) {
 	switch mode {
 	case BanMask:
 		target.RplBanList(channel, mask)
@@ -296,7 +306,7 @@ func (target *Client) RplEndOfMaskList(mode ChannelMode, channel *Channel) {
 	}
 }
 
-func (target *Client) RplBanList(channel *Channel, mask UserMask) {
+func (target *Client) RplBanList(channel *Channel, mask string) {
 	target.NumericReply(RPL_BANLIST,
 		"%s %s", channel, mask)
 }
@@ -306,7 +316,7 @@ func (target *Client) RplEndOfBanList(channel *Channel) {
 		"%s :End of channel ban list", channel)
 }
 
-func (target *Client) RplExceptList(channel *Channel, mask UserMask) {
+func (target *Client) RplExceptList(channel *Channel, mask string) {
 	target.NumericReply(RPL_EXCEPTLIST,
 		"%s %s", channel, mask)
 }
@@ -316,7 +326,7 @@ func (target *Client) RplEndOfExceptList(channel *Channel) {
 		"%s :End of channel exception list", channel)
 }
 
-func (target *Client) RplInviteList(channel *Channel, mask UserMask) {
+func (target *Client) RplInviteList(channel *Channel, mask string) {
 	target.NumericReply(RPL_INVITELIST,
 		"%s %s", channel, mask)
 }
@@ -396,6 +406,17 @@ func (target *Client) RplTime() {
 		"%s :%s", target.server.name, time.Now().Format(time.RFC1123))
 }
 
+func (target *Client) RplWhoWasUser(whoWas *WhoWas) {
+	target.NumericReply(RPL_WHOWASUSER,
+		"%s %s %s * :%s",
+		whoWas.nickname, whoWas.username, whoWas.hostname, whoWas.realname)
+}
+
+func (target *Client) RplEndOfWhoWas(nickname string) {
+	target.NumericReply(RPL_ENDOFWHOWAS,
+		"%s :End of WHOWAS", nickname)
+}
+
 //
 // errors (also numeric)
 //
@@ -515,7 +536,22 @@ func (target *Client) ErrChannelIsFull(channel *Channel) {
 		"%s :Cannot join channel (+l)", channel)
 }
 
+func (target *Client) ErrWasNoSuchNick(nickname string) {
+	target.NumericReply(ERR_WASNOSUCHNICK,
+		"%s :There was no such nickname", nickname)
+}
+
 func (target *Client) ErrInvalidCapCmd(subCommand CapSubCommand) {
 	target.NumericReply(ERR_INVALIDCAPCMD,
 		"%s :Invalid CAP subcommand", subCommand)
 }
+
+func (target *Client) ErrBannedFromChan(channel *Channel) {
+	target.NumericReply(ERR_BANNEDFROMCHAN,
+		"%s :Cannot join channel (+b)", channel)
+}
+
+func (target *Client) ErrInviteOnlyChan(channel *Channel) {
+	target.NumericReply(ERR_INVITEONLYCHAN,
+		"%s :Cannot join channel (+i)", channel)
+}
diff --git a/irc/server.go b/irc/server.go
index ff083897..9c7acae9 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -18,7 +18,7 @@ import (
 
 type Server struct {
 	channels  ChannelNameMap
-	clients   ClientNameMap
+	clients   *ClientLookupSet
 	commands  chan Command
 	ctime     time.Time
 	db        *sql.DB
@@ -29,12 +29,13 @@ type Server struct {
 	operators map[string][]byte
 	password  []byte
 	signals   chan os.Signal
+	whoWas    *WhoWasList
 }
 
 func NewServer(config *Config) *Server {
 	server := &Server{
 		channels:  make(ChannelNameMap),
-		clients:   make(ClientNameMap),
+		clients:   NewClientLookupSet(),
 		commands:  make(chan Command, 16),
 		ctime:     time.Now(),
 		db:        OpenDB(config.Server.Database),
@@ -44,6 +45,7 @@ func NewServer(config *Config) *Server {
 		newConns:  make(chan net.Conn, 16),
 		operators: config.Operators(),
 		signals:   make(chan os.Signal, 1),
+		whoWas:    NewWhoWasList(100),
 	}
 
 	if config.Server.Password != "" {
@@ -62,9 +64,17 @@ func NewServer(config *Config) *Server {
 	return server
 }
 
+func loadChannelList(channel *Channel, list string, maskMode ChannelMode) {
+	if list == "" {
+		return
+	}
+	channel.lists[maskMode].AddAll(strings.Split(list, " "))
+}
+
 func (server *Server) loadChannels() {
 	rows, err := server.db.Query(`
-        SELECT name, flags, key, topic, user_limit
+        SELECT name, flags, key, topic, user_limit, ban_list, except_list,
+               invite_list
           FROM channel`)
 	if err != nil {
 		log.Fatal("error loading channels: ", err)
@@ -72,9 +82,11 @@ func (server *Server) loadChannels() {
 	for rows.Next() {
 		var name, flags, key, topic string
 		var userLimit uint64
-		err = rows.Scan(&name, &flags, &key, &topic, &userLimit)
+		var banList, exceptList, inviteList string
+		err = rows.Scan(&name, &flags, &key, &topic, &userLimit, &banList,
+			&exceptList, &inviteList)
 		if err != nil {
-			log.Println(err)
+			log.Println("Server.loadChannels:", err)
 			continue
 		}
 
@@ -85,6 +97,9 @@ func (server *Server) loadChannels() {
 		channel.key = key
 		channel.topic = topic
 		channel.userLimit = userLimit
+		loadChannelList(channel, banList, BanMask)
+		loadChannelList(channel, exceptList, ExceptMask)
+		loadChannelList(channel, inviteList, InviteMask)
 	}
 }
 
@@ -126,7 +141,7 @@ func (server *Server) processCommand(cmd Command) {
 
 func (server *Server) Shutdown() {
 	server.db.Close()
-	for _, client := range server.clients {
+	for _, client := range server.clients.byNick {
 		client.Reply(RplNotice(server, client, "shutting down"))
 	}
 }
@@ -340,7 +355,7 @@ func (msg *RFC1459UserCommand) HandleRegServer(server *Server) {
 		client.Quit("bad password")
 		return
 	}
-	msg.HandleRegServer2(server)
+	msg.setUserInfo(server)
 }
 
 func (msg *RFC2812UserCommand) HandleRegServer(server *Server) {
@@ -357,15 +372,19 @@ func (msg *RFC2812UserCommand) HandleRegServer(server *Server) {
 		}
 		client.RplUModeIs(client)
 	}
-	msg.HandleRegServer2(server)
+	msg.setUserInfo(server)
 }
 
-func (msg *UserCommand) HandleRegServer2(server *Server) {
+func (msg *UserCommand) setUserInfo(server *Server) {
 	client := msg.Client()
 	if client.capState == CapNegotiating {
 		client.capState = CapNegotiated
 	}
+
+	server.clients.Remove(client)
 	client.username, client.realname = msg.username, msg.realname
+	server.clients.Add(client)
+
 	server.tryRegister(client)
 }
 
@@ -514,7 +533,7 @@ func (m *ModeCommand) HandleServer(s *Server) {
 		return
 	}
 
-	changes := make(ModeChanges, 0)
+	changes := make(ModeChanges, 0, len(m.changes))
 
 	for _, change := range m.changes {
 		switch change.mode {
@@ -577,19 +596,14 @@ func (m *WhoisCommand) HandleServer(server *Server) {
 	// TODO implement target query
 
 	for _, mask := range m.masks {
-		// TODO implement wildcard matching
-		mclient := server.clients.Get(mask)
-		if mclient == nil {
+		matches := server.clients.FindAll(mask)
+		if len(matches) == 0 {
 			client.ErrNoSuchNick(mask)
 			continue
 		}
-		client.RplWhoisUser(mclient)
-		if mclient.flags[Operator] {
-			client.RplWhoisOperator(mclient)
+		for mclient := range matches {
+			client.RplWhois(mclient)
 		}
-		client.RplWhoisIdle(mclient)
-		client.RplWhoisChannels(mclient)
-		client.RplEndOfWhois()
 	}
 }
 
@@ -604,9 +618,9 @@ func (msg *ChannelModeCommand) HandleServer(server *Server) {
 	channel.Mode(client, msg.changes)
 }
 
-func whoChannel(client *Client, channel *Channel) {
+func whoChannel(client *Client, channel *Channel, friends ClientSet) {
 	for member := range channel.members {
-		if !client.flags[Invisible] {
+		if !client.flags[Invisible] || friends[client] {
 			client.RplWhoReply(channel, member)
 		}
 	}
@@ -614,27 +628,21 @@ func whoChannel(client *Client, channel *Channel) {
 
 func (msg *WhoCommand) HandleServer(server *Server) {
 	client := msg.Client()
+	friends := client.Friends()
+	mask := msg.mask
 
-	// TODO implement wildcard matching
-	mask := string(msg.mask)
 	if mask == "" {
 		for _, channel := range server.channels {
-			for member := range channel.members {
-				if !client.flags[Invisible] {
-					client.RplWhoReply(channel, member)
-				}
-			}
+			whoChannel(client, channel, friends)
 		}
 	} else if IsChannel(mask) {
+		// TODO implement wildcard matching
 		channel := server.channels.Get(mask)
 		if channel != nil {
-			for member := range channel.members {
-				client.RplWhoReply(channel, member)
-			}
+			whoChannel(client, channel, friends)
 		}
 	} else {
-		mclient := server.clients.Get(mask)
-		if mclient != nil {
+		for mclient := range server.clients.FindAll(mask) {
 			client.RplWhoReply(nil, mclient)
 		}
 	}
@@ -874,3 +882,18 @@ func (msg *KillCommand) HandleServer(server *Server) {
 	quitMsg := fmt.Sprintf("KILLed by %s: %s", client.Nick(), msg.comment)
 	target.Quit(quitMsg)
 }
+
+func (msg *WhoWasCommand) HandleServer(server *Server) {
+	client := msg.Client()
+	for _, nickname := range msg.nicknames {
+		results := server.whoWas.Find(nickname, msg.count)
+		if len(results) == 0 {
+			client.ErrWasNoSuchNick(nickname)
+		} else {
+			for _, whoWas := range results {
+				client.RplWhoWasUser(whoWas)
+			}
+		}
+		client.RplEndOfWhoWas(nickname)
+	}
+}
diff --git a/irc/types.go b/irc/types.go
index 198f7b65..19014012 100644
--- a/irc/types.go
+++ b/irc/types.go
@@ -1,7 +1,6 @@
 package irc
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 )
@@ -48,9 +47,6 @@ func (set CapabilitySet) DisableString() string {
 	return strings.Join(parts, " ")
 }
 
-// a string with wildcards
-type Mask string
-
 // add, remove, list modes
 type ModeOp rune
 
@@ -112,40 +108,6 @@ func (channels ChannelNameMap) Remove(channel *Channel) error {
 	return nil
 }
 
-type ClientNameMap map[string]*Client
-
-var (
-	ErrNickMissing      = errors.New("nick missing")
-	ErrNicknameInUse    = errors.New("nickname in use")
-	ErrNicknameMismatch = errors.New("nickname mismatch")
-)
-
-func (clients ClientNameMap) Get(nick string) *Client {
-	return clients[strings.ToLower(nick)]
-}
-
-func (clients ClientNameMap) Add(client *Client) error {
-	if !client.HasNick() {
-		return ErrNickMissing
-	}
-	if clients.Get(client.nick) != nil {
-		return ErrNicknameInUse
-	}
-	clients[strings.ToLower(client.nick)] = client
-	return nil
-}
-
-func (clients ClientNameMap) Remove(client *Client) error {
-	if !client.HasNick() {
-		return ErrNickMissing
-	}
-	if clients.Get(client.nick) != client {
-		return ErrNicknameMismatch
-	}
-	delete(clients, strings.ToLower(client.nick))
-	return nil
-}
-
 type ChannelModeSet map[ChannelMode]bool
 
 func (set ChannelModeSet) String() string {
@@ -247,17 +209,3 @@ type RegServerCommand interface {
 	Command
 	HandleRegServer(*Server)
 }
-
-//
-// structs
-//
-
-type UserMask struct {
-	nickname Mask
-	username Mask
-	hostname Mask
-}
-
-func (mask *UserMask) String() string {
-	return fmt.Sprintf("%s!%s@%s", mask.nickname, mask.username, mask.hostname)
-}
diff --git a/irc/whowas.go b/irc/whowas.go
new file mode 100644
index 00000000..008ed7f3
--- /dev/null
+++ b/irc/whowas.go
@@ -0,0 +1,73 @@
+package irc
+
+type WhoWasList struct {
+	buffer []*WhoWas
+	start  uint
+	end    uint
+}
+
+type WhoWas struct {
+	nickname string
+	username string
+	hostname string
+	realname string
+}
+
+func NewWhoWasList(size uint) *WhoWasList {
+	return &WhoWasList{
+		buffer: make([]*WhoWas, size),
+	}
+}
+
+func (list *WhoWasList) Append(client *Client) {
+	list.buffer[list.end] = &WhoWas{
+		nickname: client.Nick(),
+		username: client.username,
+		hostname: client.hostname,
+		realname: client.realname,
+	}
+	list.end = (list.end + 1) % uint(len(list.buffer))
+	if list.end == list.start {
+		list.start = (list.end + 1) % uint(len(list.buffer))
+	}
+}
+
+func (list *WhoWasList) Find(nickname string, limit int64) []*WhoWas {
+	results := make([]*WhoWas, 0)
+	for whoWas := range list.Each() {
+		if nickname != whoWas.nickname {
+			continue
+		}
+		results = append(results, whoWas)
+		if int64(len(results)) >= limit {
+			break
+		}
+	}
+	return results
+}
+
+func (list *WhoWasList) prev(index uint) uint {
+	index -= 1
+	if index < 0 {
+		index += uint(len(list.buffer))
+	}
+	return index
+}
+
+// Iterate the buffer in reverse.
+func (list *WhoWasList) Each() <-chan *WhoWas {
+	ch := make(chan *WhoWas)
+	go func() {
+		defer close(ch)
+		if list.start == list.end {
+			return
+		}
+		start := list.prev(list.end)
+		end := list.prev(list.start)
+		for start != end {
+			ch <- list.buffer[start]
+			start = list.prev(start)
+		}
+	}()
+	return ch
+}