diff --git a/buildSrc/gradle.properties b/buildSrc/gradle.properties
new file mode 100644
index 00000000..5b52f144
--- /dev/null
+++ b/buildSrc/gradle.properties
@@ -0,0 +1,2 @@
+kotlin.code.style=official
+kotlin.mpp.stability.nowarn=true
diff --git a/buildSrc/src/main/kotlin/world/phantasmal/OptIns.kt b/buildSrc/src/main/kotlin/world/phantasmal/ExperimentalAnnotations.kt
similarity index 100%
rename from buildSrc/src/main/kotlin/world/phantasmal/OptIns.kt
rename to buildSrc/src/main/kotlin/world/phantasmal/ExperimentalAnnotations.kt
diff --git a/buildSrc/src/main/kotlin/world/phantasmal/jvm.gradle.kts b/buildSrc/src/main/kotlin/world/phantasmal/jvm.gradle.kts
index 25ac80ef..61047fbc 100644
--- a/buildSrc/src/main/kotlin/world/phantasmal/jvm.gradle.kts
+++ b/buildSrc/src/main/kotlin/world/phantasmal/jvm.gradle.kts
@@ -13,7 +13,9 @@ val log4jVersion: String by project.extra
 tasks.withType<KotlinCompile>().configureEach {
     kotlinOptions {
         jvmTarget = "11"
-        freeCompilerArgs = freeCompilerArgs + EXPERIMENTAL_ANNOTATION_COMPILER_ARGS
+        freeCompilerArgs = freeCompilerArgs +
+                EXPERIMENTAL_ANNOTATION_COMPILER_ARGS +
+                "-Xjvm-default=all"
     }
 }
 
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/Main.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/Main.kt
index 21f5c769..c8a6960d 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/Main.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/Main.kt
@@ -5,6 +5,7 @@ import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.hocon.Hocon
 import kotlinx.serialization.hocon.decodeFromConfig
 import mu.KotlinLogging
+import world.phantasmal.psoserv.data.AccountStore
 import world.phantasmal.psoserv.encryption.BbCipher
 import world.phantasmal.psoserv.encryption.Cipher
 import world.phantasmal.psoserv.encryption.PcCipher
@@ -71,7 +72,8 @@ fun main(args: Array<String>) {
         }
 
         // Initialize and start the server.
-        val servers = initialize(config)
+        val accountStore = AccountStore(LOGGER)
+        val servers = initialize(config, accountStore)
 
         if (servers.isEmpty()) {
             LOGGER.info { "No servers configured, stopping." }
@@ -85,7 +87,7 @@ fun main(args: Array<String>) {
     }
 }
 
-private fun initialize(config: Config): List<Server> {
+private fun initialize(config: Config, accountStore: AccountStore): List<Server> {
     val address = config.address?.let(::inet4Address) ?: DEFAULT_ADDRESS
 
     LOGGER.info { "Binding to $address." }
@@ -96,16 +98,22 @@ private fun initialize(config: Config): List<Server> {
     val blocks: Map<String, BlockInfo> = run {
         var blockI = 1
         var blockPort = DEFAULT_FIRST_SHIP_PORT + config.ships.size
+        val blocks = mutableMapOf<String, BlockInfo>()
 
-        config.blocks.associate { blockCfg ->
+        for (blockCfg in config.blocks) {
             val block = BlockInfo(
                 name = validateName("Block", blockCfg.name) ?: "block_$blockI",
                 uiName = blockCfg.uiName ?: "BLOCK${blockI.toString(2).padStart(2, '0')}",
                 bindPair = Inet4Pair(address, blockCfg.port ?: blockPort++),
             )
             blockI++
-            Pair(block.name, block)
+
+            require(blocks.put(block.name, block) == null) {
+                """Duplicate block with name ${block.name}."""
+            }
         }
+
+        blocks
     }
 
     val ships: List<ShipInfo> = run {
@@ -118,7 +126,7 @@ private fun initialize(config: Config): List<Server> {
                 uiName = shipCfg.uiName ?: "Ship $shipI",
                 bindPair = Inet4Pair(address, shipCfg.port ?: shipPort++),
                 blocks = shipCfg.blocks.map {
-                    blocks[it] ?: error("""No block with name "$it".""")
+                    blocks[it] ?: error("""No block with name $it.""")
                 },
             )
             shipI++
@@ -164,12 +172,13 @@ private fun initialize(config: Config): List<Server> {
         LOGGER.info { "Configuring account server to bind to port ${bindPair.port}." }
         LOGGER.info {
             "Account server will redirect to ${ships.size} ship servers: ${
-                ships.joinToString { """"${it.name}" (port ${it.bindPair.port})""" }
+                ships.joinToString { """${it.name} (port ${it.bindPair.port})""" }
             }."
         }
 
         servers.add(
             AccountServer(
+                accountStore,
                 bindPair,
                 ships,
             )
@@ -198,9 +207,10 @@ private fun initialize(config: Config): List<Server> {
 
         servers.add(
             BlockServer(
+                accountStore,
                 block.name,
                 block.bindPair,
-                blockNo = index + 1,
+                blockId = index + 1,
             )
         )
     }
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/data/Account.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/data/Account.kt
new file mode 100644
index 00000000..5c8e3985
--- /dev/null
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/data/Account.kt
@@ -0,0 +1,47 @@
+package world.phantasmal.psoserv.data
+
+class Account(
+    val id: Long,
+    val username: String,
+    val guildCardNo: Int,
+    val teamId: Int,
+    val characters: List<Character>,
+) {
+    init {
+        require(username.length <= 16)
+    }
+}
+
+class PlayingAccount(
+    val account: Account,
+    val char: Character,
+    val blockId: Int,
+)
+
+class Character(
+    val id: Long,
+    val accountId: Long,
+    val name: String,
+    val sectionId: SectionId,
+    val exp: Int,
+    val level: Int,
+) {
+    init {
+        require(name.length <= 16)
+        require(exp >= 0)
+        require(level in 1..200)
+    }
+}
+
+enum class SectionId {
+    Viridia,
+    Greenill,
+    Skyly,
+    Bluefull,
+    Purplenum,
+    Pinkal,
+    Redria,
+    Oran,
+    Yellowboze,
+    Whitill,
+}
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/data/AccountStore.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/data/AccountStore.kt
new file mode 100644
index 00000000..6a7159f3
--- /dev/null
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/data/AccountStore.kt
@@ -0,0 +1,111 @@
+package world.phantasmal.psoserv.data
+
+import mu.KLogger
+
+class AccountStore(private val logger: KLogger) {
+    private var nextId: Long = 1L
+    private var nextGuildCardNo: Int = 1
+
+    /**
+     * Maps usernames to accounts. Accounts are created on the fly.
+     */
+    private val accounts = mutableMapOf<String, AccountData>()
+
+    /**
+     * Logged in accounts must always be logged out with [logOut].
+     */
+    fun logIn(username: String, password: String): LogInResult =
+        synchronized(this) {
+            val data = accounts.getOrPut(username) {
+                val accountId = nextId++
+                AccountData(
+                    account = Account(
+                        id = accountId,
+                        username = username,
+                        guildCardNo = nextGuildCardNo++,
+                        teamId = 1337,
+                        characters = listOf(
+                            Character(
+                                id = nextId++,
+                                accountId = accountId,
+                                name = "${username.take(14)} 1",
+                                sectionId = SectionId.Viridia,
+                                exp = 1_000_000,
+                                level = 200,
+                            )
+                        ),
+                    ),
+                    playing = null,
+                    password = password,
+                    loggedIn = false,
+                )
+            }
+
+            if (password != data.password) {
+                LogInResult.BadPassword
+            } else if (data.loggedIn) {
+                LogInResult.AlreadyLoggedIn
+            } else {
+                data.loggedIn = true
+                LogInResult.Ok(data.account)
+            }
+        }
+
+    fun logOut(accountId: Long) {
+        synchronized(this) {
+            val data = accounts.values.find { it.account.id == accountId }
+
+            if (data == null) {
+                logger.warn {
+                    "Trying to log out nonexistent account $accountId."
+                }
+            } else {
+                if (!data.loggedIn) {
+                    logger.warn {
+                        """Trying to log out account ${data.account.id} "${data.account.username}" while it wasn't logged in."""
+                    }
+                }
+
+                data.playing = null
+                data.loggedIn = false
+            }
+        }
+    }
+
+    fun getAccountById(accountId: Long): Account? =
+        synchronized(this) {
+            accounts.values.find { it.account.id == accountId }?.account
+        }
+
+    fun setAccountPlaying(accountId: Long, char: Character, blockId: Int): Account {
+        synchronized(this) {
+            val data = accounts.values.first { it.account.id == accountId }
+            data.playing = PlayingAccount(data.account, char, blockId)
+            return data.account
+        }
+    }
+
+    fun getAccountsByBlock(blockId: Int): List<PlayingAccount> =
+        synchronized(this) {
+            accounts.values
+                .filter { it.loggedIn && it.playing?.blockId == blockId }
+                .mapNotNull { it.playing }
+        }
+
+    sealed class LogInResult {
+        class Ok(val account: Account) : LogInResult()
+        object BadPassword : LogInResult()
+        object AlreadyLoggedIn : LogInResult()
+    }
+
+    private class AccountData(
+        var account: Account,
+        var playing: PlayingAccount?,
+        val password: String,
+        var loggedIn: Boolean,
+    ) {
+        init {
+            require(password.length <= 16)
+        }
+    }
+}
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/BbMessages.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/BbMessages.kt
index a992b47d..e24e2653 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/BbMessages.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/BbMessages.kt
@@ -180,8 +180,9 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
             lobbyNo: UByte,
             blockNo: UShort,
             event: UShort,
+            players: List<LobbyPlayer>,
         ) : this(
-            buf(0x0067, 12 + 1312, flags = 1) { // TODO: Set flags to player count.
+            buf(0x0067, 12 + players.size * 1312, flags = players.size) {
                 writeUByte(clientId)
                 writeUByte(leaderId)
                 writeByte(if (disableUdp) 1 else 0)
@@ -189,7 +190,16 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
                 writeUShort(blockNo)
                 writeUShort(event)
                 writeInt(0) // Unused.
-                repeat(328) { writeInt(0) }
+
+                for (player in players) {
+                    writeInt(player.playerTag)
+                    writeInt(player.guildCardNo)
+                    repeat(5) { writeInt(0) } // Unknown.
+                    writeInt(player.clientId)
+                    writeStringUtf16(player.charName, 32)
+                    writeInt(0) // Unknown.
+                    repeat(311) { writeInt(0) }
+                }
             }
         )
 
@@ -223,10 +233,10 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
 
     // 0x0093
     class Authenticate(buffer: Buffer) : BbMessage(buffer) {
-        val guildCard: Int get() = int(4)
+        val guildCardNo: Int get() = int(4)
         val version: Short get() = short(8)
         val teamId: Int get() = int(16)
-        val userName: String get() = stringAscii(offset = 20, maxByteLength = 16)
+        val username: String get() = stringAscii(offset = 20, maxByteLength = 16)
         val password: String get() = stringAscii(offset = 68, maxByteLength = 16)
         val magic: Int get() = int(132) // Should be 0xDEADBEEF
         val charSlot: Int get() = byte(136).toInt()
@@ -301,17 +311,19 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
     }
 
     // 0x00E0
-    class GetAccount(buffer: Buffer) : BbMessage(buffer)
+    class GetAccount(buffer: Buffer) : BbMessage(buffer) {
+        constructor() : this(buf(0x00E1))
+    }
 
     // 0x00E2
     class Account(buffer: Buffer) : BbMessage(buffer) {
-        constructor(guildCard: Int, teamId: Int) : this(
+        constructor(guildCardNo: Int, teamId: Int) : this(
             buf(0x00E2, 2804) {
                 // 276 Bytes of unknown data.
                 repeat(69) { writeInt(0) }
                 writeByteArray(DEFAULT_KEYBOARD_CONFIG)
                 writeByteArray(DEFAULT_GAMEPAD_CONFIG)
-                writeInt(guildCard)
+                writeInt(guildCardNo)
                 writeInt(teamId)
                 // 2092 Bytes of team data.
                 repeat(523) { writeInt(0) }
@@ -383,12 +395,26 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
 
     // 0x00E6
     class AuthData(buffer: Buffer) : BbMessage(buffer) {
+        var status: AuthStatus
+            get() = when (val value = int(0)) {
+                0 -> AuthStatus.Success
+                1 -> AuthStatus.Error
+                8 -> AuthStatus.Nonexistent
+                else -> AuthStatus.Unknown(value)
+            }
+            set(status) = setInt(0, when (status) {
+                AuthStatus.Success -> 0
+                AuthStatus.Error -> 1
+                AuthStatus.Nonexistent -> 8
+                is AuthStatus.Unknown -> status.value
+            })
+
         constructor(
             status: AuthStatus,
-            guildCard: Int,
+            guildCardNo: Int,
             teamId: Int,
-            slot: Int,
-            selected: Boolean,
+            charSlot: Int,
+            charSelected: Boolean,
         ) : this(
             buf(0x00E6, 60) {
                 writeInt(
@@ -396,27 +422,31 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
                         AuthStatus.Success -> 0
                         AuthStatus.Error -> 1
                         AuthStatus.Nonexistent -> 8
+                        is AuthStatus.Unknown -> status.value
                     }
                 )
                 writeInt(0x10000)
-                writeInt(guildCard)
+                writeInt(guildCardNo)
                 writeInt(teamId)
                 writeInt(
                     if (status == AuthStatus.Success) (0xDEADBEEF).toInt() else 0
                 )
-                writeByte(slot.toByte())
-                writeByte(if (selected) 1 else 0)
+                writeByte(charSlot.toByte())
+                writeByte(if (charSelected) 1 else 0)
                 // 34 Bytes of unknown data.
                 writeShort(0)
                 repeat(8) { writeInt(0) }
                 writeInt(0x102)
             }
         )
+
+        override fun toString(): String =
+            messageString("status" to status)
     }
 
     // 0x00E7
     class FullCharacterData(buffer: Buffer) : BbMessage(buffer) {
-        constructor(char: PsoCharData) : this(
+        constructor(char: PsoCharData, name: String, sectionId: Byte, charClass: Byte) : this(
             buf(0x00E7, 14744) {
                 repeat(211) { writeInt(0) }
                 repeat(3) { writeShort(0) } // ATP/MST/EVP
@@ -426,7 +456,15 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
                 repeat(2) { writeInt(0) } // Unknown.
                 writeInt(char.level)
                 writeInt(char.exp)
-                repeat(2835) { writeInt(0) }
+                repeat(92) { writeInt(0) } // Rest of char.
+                repeat(1275) { writeInt(0) }
+                writeStringUtf16(name, byteLength = 48)
+                repeat(8) { writeInt(0) } // Team name.
+                repeat(44) { writeInt(0) } // Guild card description.
+                writeShort(0) // Reserved.
+                writeByte(sectionId)
+                writeByte(charClass)
+                repeat(1403) { writeInt(0) }
                 writeByteArray(DEFAULT_KEYBOARD_CONFIG)
                 writeByteArray(DEFAULT_GAMEPAD_CONFIG)
                 repeat(527) { writeInt(0) }
@@ -523,8 +561,15 @@ sealed class BbMessage(override val buffer: Buffer) : AbstractMessage(BB_HEADER_
     }
 }
 
-enum class AuthStatus {
-    Success, Error, Nonexistent
+sealed class AuthStatus {
+    object Success : AuthStatus()
+    object Error : AuthStatus()
+    object Nonexistent : AuthStatus()
+    class Unknown(val value: Int) : AuthStatus() {
+        override fun toString(): String = "Unknown[$value]"
+    }
+
+    override fun toString(): String = this::class.simpleName!!
 }
 
 class PsoCharacter(
@@ -561,7 +606,7 @@ class GuildCardEntry(
 )
 
 class GuildCard(
-    val entries: List<GuildCardEntry>
+    val entries: List<GuildCardEntry>,
 )
 
 class FileListEntry(
@@ -610,3 +655,10 @@ class PsoCharData(
     val level: Int,
     val exp: Int,
 )
+
+class LobbyPlayer(
+    val playerTag: Int,
+    val guildCardNo: Int,
+    val clientId: Int,
+    val charName: String,
+)
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/Messages.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/Messages.kt
index 8ff7eaea..3389f50f 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/Messages.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/messages/Messages.kt
@@ -80,6 +80,10 @@ abstract class AbstractMessage(override val headerSize: Int) : Message {
         buffer.setShort(headerSize + offset, value)
     }
 
+    protected fun setInt(offset: Int, value: Int) {
+        buffer.setInt(headerSize + offset, value)
+    }
+
     protected fun setByteArray(offset: Int, array: ByteArray) {
         for ((index, byte) in array.withIndex()) {
             setByte(offset + index, byte)
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AccountServer.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AccountServer.kt
index 65ea15a4..f2926730 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AccountServer.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AccountServer.kt
@@ -4,12 +4,15 @@ import world.phantasmal.core.math.clamp
 import world.phantasmal.psolib.Endianness
 import world.phantasmal.psolib.buffer.Buffer
 import world.phantasmal.psolib.cursor.cursor
+import world.phantasmal.psoserv.data.AccountStore
+import world.phantasmal.psoserv.data.AccountStore.LogInResult
 import world.phantasmal.psoserv.encryption.BbCipher
 import world.phantasmal.psoserv.encryption.Cipher
 import world.phantasmal.psoserv.messages.*
 import world.phantasmal.psoserv.utils.crc32Checksum
 
 class AccountServer(
+    private val accountStore: AccountStore,
     bindPair: Inet4Pair,
     private val ships: List<ShipInfo>,
 ) : GameServer<BbMessage>("account", bindPair) {
@@ -23,11 +26,10 @@ class AccountServer(
         serverCipher: Cipher,
         clientCipher: Cipher,
     ): ClientReceiver<BbMessage> = object : ClientReceiver<BbMessage> {
+        private var accountId: Long? = null
         private val guildCardBuffer = Buffer.withSize(54672)
         private var fileChunkNo = 0
-        private var guildCard: Int = -1
-        private var teamId: Int = -1
-        private var slot: Int = 0
+        private var charSlot: Int = 0
         private var charSelected: Boolean = false
 
         init {
@@ -43,88 +45,124 @@ class AccountServer(
 
         override fun process(message: BbMessage): Boolean = when (message) {
             is BbMessage.Authenticate -> {
-                // TODO: Actual authentication.
-                guildCard = message.guildCard
-                teamId = message.teamId
-                ctx.send(
-                    BbMessage.AuthData(
-                        AuthStatus.Success,
-                        guildCard,
-                        teamId,
-                        slot,
-                        charSelected,
+                when (
+                    val result = accountStore.logIn(
+                        message.username,
+                        message.password,
                     )
-                )
+                ) {
+                    is LogInResult.Ok -> {
+                        val account = result.account
+                        this.accountId = account.id
 
-                // When the player has selected a character, we send him the list of ships to
-                // choose from.
-                if (message.charSelected) {
-                    ctx.send(BbMessage.ShipList(ships.map { it.uiName }))
+                        charSlot = message.charSlot
+                        charSelected = message.charSelected
+
+                        ctx.send(
+                            BbMessage.AuthData(
+                                AuthStatus.Success,
+                                account.guildCardNo,
+                                account.teamId,
+                                charSlot,
+                                charSelected,
+                            )
+                        )
+
+                        // When the player has selected a character, we send him the list of ships
+                        // to choose from.
+                        if (charSelected) {
+                            ctx.send(BbMessage.ShipList(ships.map { it.uiName }))
+                        }
+                    }
+                    LogInResult.BadPassword -> {
+                        ctx.send(
+                            BbMessage.AuthData(
+                                AuthStatus.Nonexistent,
+                                message.guildCardNo,
+                                message.teamId,
+                                message.charSlot,
+                                message.charSelected,
+                            )
+                        )
+                    }
+                    LogInResult.AlreadyLoggedIn -> {
+                        ctx.send(
+                            BbMessage.AuthData(
+                                AuthStatus.Error,
+                                message.guildCardNo,
+                                message.teamId,
+                                message.charSlot,
+                                message.charSelected,
+                            )
+                        )
+                    }
                 }
 
                 true
             }
 
             is BbMessage.GetAccount -> {
-                // TODO: Send correct guild card number and team ID.
-                ctx.send(BbMessage.Account(0, 0))
+                accountId?.let(accountStore::getAccountById)?.let {
+                    ctx.send(BbMessage.Account(it.guildCardNo, it.teamId))
+                }
 
                 true
             }
 
             is BbMessage.CharSelect -> {
-                if (message.selected) {
-                    // Player has chosen a character.
-                    // TODO: Verify slot.
-                    if (slot in 0..3) {
-                        slot = message.slot
+                val account = accountId?.let(accountStore::getAccountById)
+
+                if (account != null && message.slot in account.characters.indices) {
+                    if (message.selected) {
+                        // Player has chosen a character.
+                        charSlot = message.slot
                         charSelected = true
                         ctx.send(
                             BbMessage.AuthData(
                                 AuthStatus.Success,
-                                guildCard,
-                                teamId,
-                                slot,
+                                account.guildCardNo,
+                                account.teamId,
+                                charSlot,
                                 charSelected,
                             )
                         )
                         ctx.send(
-                            BbMessage.CharSelectAck(slot, CharSelectStatus.Select)
+                            BbMessage.CharSelectAck(charSlot, CharSelectStatus.Select)
                         )
                     } else {
+                        // Player is previewing characters.
+                        val char = account.characters[message.slot]
                         ctx.send(
-                            BbMessage.CharSelectAck(slot, CharSelectStatus.Nonexistent)
+                            BbMessage.Char(
+                                PsoCharacter(
+                                    slot = message.slot,
+                                    exp = char.exp,
+                                    level = char.level - 1,
+                                    guildCardString = "",
+                                    nameColor = 0,
+                                    model = 0,
+                                    nameColorChecksum = 0,
+                                    sectionId = char.sectionId.ordinal,
+                                    characterClass = 0,
+                                    costume = 0,
+                                    skin = 0,
+                                    face = 0,
+                                    head = 0,
+                                    hair = 0,
+                                    hairRed = 0,
+                                    hairGreen = 0,
+                                    hairBlue = 0,
+                                    propX = 0.5,
+                                    propY = 0.5,
+                                    name = char.name,
+                                    playTime = 0,
+                                )
+                            )
                         )
                     }
                 } else {
-                    // Player is previewing characters.
-                    // TODO: Look up character data.
                     ctx.send(
-                        BbMessage.Char(
-                            PsoCharacter(
-                                slot = message.slot,
-                                exp = 0,
-                                level = 0,
-                                guildCardString = "",
-                                nameColor = 0,
-                                model = 0,
-                                nameColorChecksum = 0,
-                                sectionId = message.slot,
-                                characterClass = message.slot,
-                                costume = 0,
-                                skin = 0,
-                                face = 0,
-                                head = 0,
-                                hair = 0,
-                                hairRed = 0,
-                                hairGreen = 0,
-                                hairBlue = 0,
-                                propX = 0.5,
-                                propY = 0.5,
-                                name = "Phantasmal ${message.slot}",
-                                playTime = 0,
-                            )
-                        )
+                        BbMessage.CharSelectAck(message.slot, CharSelectStatus.Nonexistent)
                     )
                 }
 
@@ -205,17 +243,34 @@ class AccountServer(
                         )
                     }
 
-                    // Disconnect.
+                    // Log out and disconnect.
+                    logOut()
                     false
                 } else {
                     true
                 }
             }
 
-            is BbMessage.Disconnect -> false
+            is BbMessage.Disconnect -> {
+                // Log out and disconnect.
+                logOut()
+                false
+            }
 
             else -> ctx.unexpectedMessage(message)
         }
+
+        override fun connectionClosed() {
+            logOut()
+        }
+
+        private fun logOut() {
+            try {
+                accountId?.let(accountStore::logOut)
+            } finally {
+                accountId = null
+            }
+        }
     }
 
     companion object {
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AuthServer.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AuthServer.kt
index f7be0017..693aaf3f 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AuthServer.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/AuthServer.kt
@@ -35,14 +35,15 @@ class AuthServer(
 
         override fun process(message: BbMessage): Boolean = when (message) {
             is BbMessage.Authenticate -> {
-                // TODO: Actual authentication.
+                // Don't actually authenticate, since we're simply redirecting the player to the
+                // account server.
                 ctx.send(
                     BbMessage.AuthData(
                         AuthStatus.Success,
-                        message.guildCard,
+                        message.guildCardNo,
                         message.teamId,
-                        slot = 0,
-                        selected = false,
+                        charSlot = 0,
+                        charSelected = false,
                     )
                 )
                 ctx.send(
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/BlockServer.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/BlockServer.kt
index 18634338..38841199 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/BlockServer.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/BlockServer.kt
@@ -1,16 +1,16 @@
 package world.phantasmal.psoserv.servers
 
+import world.phantasmal.psoserv.data.AccountStore
+import world.phantasmal.psoserv.data.AccountStore.LogInResult
 import world.phantasmal.psoserv.encryption.BbCipher
 import world.phantasmal.psoserv.encryption.Cipher
-import world.phantasmal.psoserv.messages.AuthStatus
-import world.phantasmal.psoserv.messages.BbMessage
-import world.phantasmal.psoserv.messages.BbMessageDescriptor
-import world.phantasmal.psoserv.messages.PsoCharData
+import world.phantasmal.psoserv.messages.*
 
 class BlockServer(
+    private val accountStore: AccountStore,
     name: String,
     bindPair: Inet4Pair,
-    private val blockNo: Int,
+    private val blockId: Int,
 ) : GameServer<BbMessage>(name, bindPair) {
 
     override val messageDescriptor = BbMessageDescriptor
@@ -22,6 +22,8 @@ class BlockServer(
         serverCipher: Cipher,
         clientCipher: Cipher,
     ): ClientReceiver<BbMessage> = object : ClientReceiver<BbMessage> {
+        private var accountId: Long? = null
+
         init {
             ctx.send(
                 BbMessage.InitEncryption(
@@ -35,27 +37,78 @@ class BlockServer(
 
         override fun process(message: BbMessage): Boolean = when (message) {
             is BbMessage.Authenticate -> {
-                // TODO: Actual authentication.
-                ctx.send(
-                    BbMessage.AuthData(
-                        AuthStatus.Success,
-                        message.guildCard,
-                        message.teamId,
-                        message.charSlot,
-                        message.charSelected,
-                    )
-                )
-                ctx.send(BbMessage.LobbyList())
-                ctx.send(
-                    BbMessage.FullCharacterData(
-                        PsoCharData(
-                            hp = 20,
-                            level = 0,
-                            exp = 0,
+                when (
+                    val result = accountStore.logIn(message.username, message.password)
+                ) {
+                    is LogInResult.Ok -> {
+                        accountId = result.account.id
+                        val char = result.account.characters.getOrNull(message.charSlot)
+
+                        if (char == null) {
+                            ctx.send(
+                                BbMessage.AuthData(
+                                    AuthStatus.Nonexistent,
+                                    message.guildCardNo,
+                                    message.teamId,
+                                    message.charSlot,
+                                    message.charSelected,
+                                )
+                            )
+                        } else {
+                            val account = accountStore.setAccountPlaying(
+                                result.account.id,
+                                char,
+                                blockId,
+                            )
+                            ctx.send(
+                                BbMessage.AuthData(
+                                    AuthStatus.Success,
+                                    account.guildCardNo,
+                                    account.teamId,
+                                    message.charSlot,
+                                    message.charSelected,
+                                )
+                            )
+
+                            ctx.send(BbMessage.LobbyList())
+                            ctx.send(
+                                BbMessage.FullCharacterData(
+                                    PsoCharData(
+                                        hp = 0,
+                                        level = char.level - 1,
+                                        exp = char.exp,
+                                    ),
+                                    char.name,
+                                    char.sectionId.ordinal.toByte(),
+                                    charClass = 0,
+                                )
+                            )
+                            ctx.send(BbMessage.GetCharData())
+                        }
+                    }
+                    LogInResult.BadPassword -> {
+                        ctx.send(
+                            BbMessage.AuthData(
+                                AuthStatus.Nonexistent,
+                                message.guildCardNo,
+                                message.teamId,
+                                message.charSlot,
+                                message.charSelected,
+                            )
                         )
-                    )
-                )
-                ctx.send(BbMessage.GetCharData())
+                    }
+                    LogInResult.AlreadyLoggedIn -> {
+                        ctx.send(
+                            BbMessage.AuthData(
+                                AuthStatus.Error,
+                                message.guildCardNo,
+                                message.teamId,
+                                message.charSlot,
+                                message.charSelected,
+                            )
+                        )
+                    }
+                }
 
                 true
             }
@@ -67,15 +120,41 @@ class BlockServer(
                         leaderId = 0u,
                         disableUdp = true,
                         lobbyNo = 0u,
-                        blockNo = blockNo.toUShort(),
+                        blockNo = blockId.toUShort(),
                         event = 0u,
+                        players = accountStore.getAccountsByBlock(blockId).map {
+                            LobbyPlayer(
+                                playerTag = 0,
+                                guildCardNo = it.account.guildCardNo,
+                                clientId = 0,
+                                charName = it.char.name,
+                            )
+                        }
                     )
                 )
 
                 true
             }
 
+            is BbMessage.Disconnect -> {
+                // Log out and disconnect.
+                logOut()
+                false
+            }
+
             else -> ctx.unexpectedMessage(message)
         }
+
+        override fun connectionClosed() {
+            logOut()
+        }
+
+        private fun logOut() {
+            try {
+                accountId?.let(accountStore::logOut)
+            } finally {
+                accountId = null
+            }
+        }
     }
 }
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/GameServer.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/GameServer.kt
index adab6172..2a275d9f 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/GameServer.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/GameServer.kt
@@ -33,6 +33,7 @@ abstract class GameServer<MessageType : Message>(
 
     protected interface ClientReceiver<MessageType : Message> {
         fun process(message: MessageType): Boolean
+        fun connectionClosed() {}
     }
 
     protected class ClientContext<MessageType : Message>(
@@ -74,5 +75,9 @@ abstract class GameServer<MessageType : Message>(
                 // Close the connection.
                 ProcessResult.Done
             }
+
+        override fun socketClosed() {
+            receiver.connectionClosed()
+        }
     }
 }
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/ShipServer.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/ShipServer.kt
index 887c6d3c..b110b6b8 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/ShipServer.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/ShipServer.kt
@@ -36,11 +36,12 @@ class ShipServer(
 
         override fun process(message: BbMessage): Boolean = when (message) {
             is BbMessage.Authenticate -> {
-                // TODO: Actual authentication.
+                // Don't actually authenticate, since we're simply letting the player choose a block
+                // and then redirecting him to the corresponding block server.
                 ctx.send(
                     BbMessage.AuthData(
                         AuthStatus.Success,
-                        message.guildCard,
+                        message.guildCardNo,
                         message.teamId,
                         message.charSlot,
                         message.charSelected,
diff --git a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/SocketHandler.kt b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/SocketHandler.kt
index 47e761d9..d479d40e 100644
--- a/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/SocketHandler.kt
+++ b/psoserv/src/main/kotlin/world/phantasmal/psoserv/servers/SocketHandler.kt
@@ -48,6 +48,7 @@ abstract class SocketHandler<MessageType : Message>(
 
                 if (readSize == -1) {
                     // Close the connection if no more bytes available.
+                    logger.debug { "$name ($sockName) end of stream." }
                     break@readLoop
                 }