diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f655bb0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/exe/
diff --git a/build-all b/build-all
index 1654c5a..ffc0eb3 100755
--- a/build-all
+++ b/build-all
@@ -1,3 +1,3 @@
 #!/bin/sh
 
-go build ./cmd/...
+go build -o ./exe ./cmd/...
diff --git a/cmd/shserver/main.go b/cmd/shserver/main.go
index 858c617..84099e5 100644
--- a/cmd/shserver/main.go
+++ b/cmd/shserver/main.go
@@ -22,11 +22,11 @@ func main() {
 		os.Exit(1)
 	}
 
-	server, err := servers.NewServer(addr)
+	server, err := servers.NewServer(servers.ServerConfig{})
 	if err != nil {
 		log.Fatalf("servers.New(...): %s\n", err)
 	}
 
 	log.Printf("Trying to serve at %q\n", addr)
-	server.ListenAndServe()
+	server.ListenAndServe(addr)
 }
diff --git a/cmd/shutil/main.go b/cmd/shutil/main.go
new file mode 100644
index 0000000..8e14dd4
--- /dev/null
+++ b/cmd/shutil/main.go
@@ -0,0 +1,36 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	"surdeus.su/core/cli/mtool"
+	"surdeus.su/util/shelldoor/servers"
+)
+
+var HashTool = mtool.T("hash").
+	Func(func(flags *mtool.Flags) {
+		passwords := flags.Parse()
+		if len(passwords) < 1 {
+			flags.Usage()
+			os.Exit(1)
+		}
+		for _, password := range passwords {
+			hash, err := servers.HashPassword(
+				servers.Password(password),
+			)
+			if err != nil {
+				log.Printf("HashPassword(...): %s\n", err)
+				continue
+			}
+			log.Printf("%s\n", hash)
+		}
+	})
+
+var Tool = mtool.T("shutil").Subs(
+	HashTool,
+)
+
+func main() {
+	Tool.Run(os.Args[1:])
+}
diff --git a/go.mod b/go.mod
index 96317b2..630a0de 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,8 @@
 module surdeus.su/util/shelldoor
 
 go 1.22.7
+
+require (
+	golang.org/x/crypto v0.27.0
+	surdeus.su/core/cli v0.8.0
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..3f90ccc
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,4 @@
+golang.org/x/crypto v0.27.0 h1:GXm2NjJrPaiv/h1tb2UH8QfgC/hOf/+z0p6PT8o1w7A=
+golang.org/x/crypto v0.27.0/go.mod h1:1Xngt8kV6Dvbssa53Ziq6Eqn0HqbZi5Z6R0ZpwQzt70=
+surdeus.su/core/cli v0.8.0 h1:HGmRqWl6W5DxFX1nVkUpS+cK0BgYYJdYrZY3VTq3C4k=
+surdeus.su/core/cli v0.8.0/go.mod h1:r9JtQz3aEJzpYzMaNUNQHJoYkoWKNPi047qhd5uGlmA=
diff --git a/servers/client.go b/servers/client.go
index f5149fb..f31def7 100644
--- a/servers/client.go
+++ b/servers/client.go
@@ -2,10 +2,19 @@ package servers
 
 import "net"
 
+// The type represents authentication request
+// from clients.
+type ClientAuthRequest struct {
+	Login    Login
+	Password Password
+}
+
+// The type represents the controlling client.
 type Client struct {
 	conn net.Conn
 }
 
+// Returns the new client on the specified connection.
 func NewClient(conn net.Conn) *Client {
 	ret := &Client{}
 	ret.conn = conn
diff --git a/servers/config.go b/servers/config.go
new file mode 100644
index 0000000..83878b8
--- /dev/null
+++ b/servers/config.go
@@ -0,0 +1,20 @@
+package servers
+
+// The type represents unique bot authentication
+// token which is needed to connect to the bot net.
+type BotAuthToken int64
+
+// More or less secure storage for passwords
+// identifying them by login.
+type PasswordMap map[Login]PasswordHash
+
+// The type represents sever configuration.
+type ServerConfig struct {
+	// The map stores clients that can login
+	// and the credentials.
+	Auth PasswordMap `json:"auth"`
+
+	// The token must be unique so only
+	// needed bots can join the bot net.
+	BotAuthToken BotAuthToken `json:"bot_auth_token"`
+}
diff --git a/servers/hash.go b/servers/hash.go
new file mode 100644
index 0000000..4e9f69f
--- /dev/null
+++ b/servers/hash.go
@@ -0,0 +1,24 @@
+package servers
+
+import "golang.org/x/crypto/bcrypt"
+
+// The type represents login used to login.
+type Login string
+
+// The type represents passwords used to login.
+type Password string
+
+// The type represents hash of the password.
+type PasswordHash string
+
+// Simple hashing password function.
+func HashPassword(password Password) (PasswordHash, error) {
+	bts, err := bcrypt.GenerateFromPassword([]byte(password), 14)
+	return PasswordHash(bts), err
+}
+
+// Check for password to match the hash.
+func PasswordMatchHash(password Password, hash PasswordHash) bool {
+	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
+	return err == nil
+}
diff --git a/servers/server.go b/servers/server.go
index 04fc3db..98635b5 100644
--- a/servers/server.go
+++ b/servers/server.go
@@ -5,43 +5,41 @@ import (
 	"net"
 )
 
-type BotRequest struct {
-}
-
-type BotResponse struct {
-}
-
-type ClientRequest struct {
-}
-
-type ClientResponse struct {
-	Error string
-	Text  string
-}
-
+// The type represents server that connects
+// clients and the bots together.
 type Server struct {
 	addr      string
 	listenner net.Listener
 	bots      []*Bot
 	clients   []*Client
+	config    ServerConfig
 }
 
-func NewServer(addr string) (*Server, error) {
+// Returns the new server with the specified configuration.
+func NewServer(config ServerConfig) (*Server, error) {
 	srv := &Server{}
-	srv.addr = addr
+	srv.config = config
 	return srv, nil
 }
 
+// The method handles the specified connection
+// checking out if it is client or a bot.
 func (srv *Server) HandleConn(conn net.Conn) {
 	defer conn.Close()
+
+	for {
+
+	}
 }
 
-func (srv *Server) ListenAndServe() error {
+// Start listening and serve both clients and bots.
+func (srv *Server) ListenAndServe(addr string) error {
 	var err error
-	srv.listenner, err = net.Listen("tcp", srv.addr)
+	srv.listenner, err = net.Listen("tcp", addr)
 	if err != nil {
 		return err
 	}
+	srv.addr = addr
 
 	for {
 		conn, err := srv.listenner.Accept()