diff --git a/README.md b/README.md
index afefcf3..d585868 100644
--- a/README.md
+++ b/README.md
@@ -36,33 +36,38 @@ docker-compose up
 
 ## Environment Variables
 
-| Variable                    | Description                                                                                                                                                  | Default                            |
-|-----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------|
-| `BASE_PATH`                 | Set this variable if you run wireguard-ui under a subpath of your reverse proxy virtual host (e.g. /wireguard))                                              | N/A                                |
-| `BIND_ADDRESS`              | The addresses that can access to the web interface and the port, use unix:///abspath/to/file.socket for unix domain socket.                                  | 0.0.0.0:80                         |
-| `SESSION_SECRET`            | The secret key used to encrypt the session cookies. Set this to a random value                                                                               | N/A                                |
-| `WGUI_USERNAME`             | The username for the login page. Used for db initialization only                                                                                             | `admin`                            |
-| `WGUI_PASSWORD`             | The password for the user on the login page. Will be hashed automatically. Used for db initialization only                                                   | `admin`                            |
-| `WGUI_PASSWORD_HASH`        | The password hash for the user on the login page. (alternative to `WGUI_PASSWORD`). Used for db initialization only                                          | N/A                                |
-| `WGUI_ENDPOINT_ADDRESS`     | The default endpoint address used in global settings where clients should connect to                                                                         | Resolved to your public ip address |
-| `WGUI_FAVICON_FILE_PATH`    | The file path used as website favicon                                                                                                                        | Embedded WireGuard logo            |
-| `WGUI_DNS`                  | The default DNS servers (comma-separated-list) used in the global settings                                                                                   | `1.1.1.1`                          |
-| `WGUI_MTU`                  | The default MTU used in global settings                                                                                                                      | `1450`                             |
-| `WGUI_PERSISTENT_KEEPALIVE` | The default persistent keepalive for WireGuard in global settings                                                                                            | `15`                               |
-| `WGUI_FIREWALL_MARK`        | The default WireGuard firewall mark                                                                                                                          | `0xca6c`  (51820)                  |
-| `WGUI_TABLE`                | The default WireGuard table value settings                                                                                                                   | `auto`                             |
-| `WGUI_CONFIG_FILE_PATH`     | The default WireGuard config file path used in global settings                                                                                               | `/etc/wireguard/wg0.conf`          |
-| `WGUI_LOG_LEVEL`            | The default log level. Possible values: `DEBUG`, `INFO`, `WARN`, `ERROR`, `OFF`                                                                              | `INFO`                             |
-| `WG_CONF_TEMPLATE`          | The custom `wg.conf` config file template. Please refer to our [default template](https://github.com/ngoduykhanh/wireguard-ui/blob/master/templates/wg.conf) | N/A                                |
-| `EMAIL_FROM_ADDRESS`        | The sender email address                                                                                                                                     | N/A                                |
-| `EMAIL_FROM_NAME`           | The sender name                                                                                                                                              | `WireGuard UI`                     |
-| `SENDGRID_API_KEY`          | The SendGrid api key                                                                                                                                         | N/A                                |
-| `SMTP_HOSTNAME`             | The SMTP IP address or hostname                                                                                                                              | `127.0.0.1`                        |
-| `SMTP_PORT`                 | The SMTP port                                                                                                                                                | `25`                               |
-| `SMTP_USERNAME`             | The SMTP username                                                                                                                                            | N/A                                |
-| `SMTP_PASSWORD`             | The SMTP user password                                                                                                                                       | N/A                                |
-| `SMTP_AUTH_TYPE`            | The SMTP authentication type. Possible values: `PLAIN`, `LOGIN`, `NONE`                                                                                      | `NONE`                             |
-| `SMTP_ENCRYPTION`           | the encryption method. Possible values: `NONE`, `SSL`, `SSLTLS`, `TLS`, `STARTTLS`                                                                           | `STARTTLS`                         |
+| Variable                    | Description                                                                                                                                                                 | Default                            |
+|-----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------|
+| `BASE_PATH`                 | Set this variable if you run wireguard-ui under a subpath of your reverse proxy virtual host (e.g. /wireguard)                                                              | N/A                                |
+| `BIND_ADDRESS`              | The addresses that can access to the web interface and the port, use unix:///abspath/to/file.socket for unix domain socket.                                                 | 0.0.0.0:80                         |
+| `SESSION_SECRET`            | The secret key used to encrypt the session cookies. Set this to a random value                                                                                              | N/A                                |
+| `SESSION_SECRET_FILE`       | Optional filepath for the secret key used to encrypt the session cookies. Leave `SESSION_SECRET` blank to take effect                                                       | N/A                                |
+| `WGUI_USERNAME`             | The username for the login page. Used for db initialization only                                                                                                            | `admin`                            |
+| `WGUI_PASSWORD`             | The password for the user on the login page. Will be hashed automatically. Used for db initialization only                                                                  | `admin`                            |
+| `WGUI_PASSWORD_FILE`        | Optional filepath for the user login password. Will be hashed automatically. Used for db initialization only. Leave `WGUI_PASSWORD` blank to take effect                    | N/A                                |
+| `WGUI_PASSWORD_HASH`        | The password hash for the user on the login page. (alternative to `WGUI_PASSWORD`). Used for db initialization only                                                         | N/A                                |
+| `WGUI_PASSWORD_HASH_FILE`   | Optional filepath for the user login password hash. (alternative to `WGUI_PASSWORD_FILE`). Used for db initialization only. Leave `WGUI_PASSWORD_HASH` blank to take effect | N/A                                |
+| `WGUI_ENDPOINT_ADDRESS`     | The default endpoint address used in global settings where clients should connect to                                                                                        | Resolved to your public ip address |
+| `WGUI_FAVICON_FILE_PATH`    | The file path used as website favicon                                                                                                                                       | Embedded WireGuard logo            |
+| `WGUI_DNS`                  | The default DNS servers (comma-separated-list) used in the global settings                                                                                                  | `1.1.1.1`                          |
+| `WGUI_MTU`                  | The default MTU used in global settings                                                                                                                                     | `1450`                             |
+| `WGUI_PERSISTENT_KEEPALIVE` | The default persistent keepalive for WireGuard in global settings                                                                                                           | `15`                               |
+| `WGUI_FIREWALL_MARK`        | The default WireGuard firewall mark                                                                                                                                         | `0xca6c`  (51820)                  |
+| `WGUI_TABLE`                | The default WireGuard table value settings                                                                                                                                  | `auto`                             |
+| `WGUI_CONFIG_FILE_PATH`     | The default WireGuard config file path used in global settings                                                                                                              | `/etc/wireguard/wg0.conf`          |
+| `WGUI_LOG_LEVEL`            | The default log level. Possible values: `DEBUG`, `INFO`, `WARN`, `ERROR`, `OFF`                                                                                             | `INFO`                             |
+| `WG_CONF_TEMPLATE`          | The custom `wg.conf` config file template. Please refer to our [default template](https://github.com/ngoduykhanh/wireguard-ui/blob/master/templates/wg.conf)                | N/A                                |
+| `EMAIL_FROM_ADDRESS`        | The sender email address                                                                                                                                                    | N/A                                |
+| `EMAIL_FROM_NAME`           | The sender name                                                                                                                                                             | `WireGuard UI`                     |
+| `SENDGRID_API_KEY`          | The SendGrid api key                                                                                                                                                        | N/A                                |
+| `SENDGRID_API_KEY_FILE`     | Optional filepath for the SendGrid api key. Leave `SENDGRID_API_KEY` blank to take effect                                                                                   | N/A                                |
+| `SMTP_HOSTNAME`             | The SMTP IP address or hostname                                                                                                                                             | `127.0.0.1`                        |
+| `SMTP_PORT`                 | The SMTP port                                                                                                                                                               | `25`                               |
+| `SMTP_USERNAME`             | The SMTP username                                                                                                                                                           | N/A                                |
+| `SMTP_PASSWORD`             | The SMTP user password                                                                                                                                                      | N/A                                |
+| `SMTP_PASSWORD_FILE`        | Optional filepath for the SMTP user password. Leave `SMTP_PASSWORD` blank to take effect                                                                                    | N/A                                |
+| `SMTP_AUTH_TYPE`            | The SMTP authentication type. Possible values: `PLAIN`, `LOGIN`, `NONE`                                                                                                     | `NONE`                             |
+| `SMTP_ENCRYPTION`           | The encryption method. Possible values: `NONE`, `SSL`, `SSLTLS`, `TLS`, `STARTTLS`                                                                                          | `STARTTLS`                         |
 
 ### Defaults for server configuration
 
diff --git a/handler/routes.go b/handler/routes.go
index a2ceeaf..aa5461b 100644
--- a/handler/routes.go
+++ b/handler/routes.go
@@ -8,6 +8,7 @@ import (
 	"io/fs"
 	"net/http"
 	"os"
+	"regexp"
 	"sort"
 	"strings"
 	"time"
@@ -26,6 +27,8 @@ import (
 	"github.com/ngoduykhanh/wireguard-ui/util"
 )
 
+var usernameRegexp = regexp.MustCompile("^\\w[\\w\\-.]*$")
+
 // Health check handler
 func Health() echo.HandlerFunc {
 	return func(c echo.Context) error {
@@ -63,6 +66,10 @@ func Login(db store.IStore) echo.HandlerFunc {
 		password := data["password"].(string)
 		rememberMe := data["rememberMe"].(bool)
 
+		if !usernameRegexp.MatchString(username) {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid username"})
+		}
+
 		dbuser, err := db.GetUserByName(username)
 		if err != nil {
 			return c.JSON(http.StatusInternalServerError, jsonHTTPResponse{false, "Cannot query user from DB"})
@@ -135,9 +142,12 @@ func GetUsers(db store.IStore) echo.HandlerFunc {
 // GetUser handler returns a JSON object of single user
 func GetUser(db store.IStore) echo.HandlerFunc {
 	return func(c echo.Context) error {
-
 		username := c.Param("username")
 
+		if !usernameRegexp.MatchString(username) {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid username"})
+		}
+
 		if !isAdmin(c) && (username != currentUser(c)) {
 			return c.JSON(http.StatusForbidden, jsonHTTPResponse{false, "Manager cannot access other user data"})
 		}
@@ -200,12 +210,16 @@ func UpdateUser(db store.IStore) echo.HandlerFunc {
 			admin = false
 		}
 
+		if !usernameRegexp.MatchString(previousUsername) {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid username"})
+		}
+
 		user, err := db.GetUserByName(previousUsername)
 		if err != nil {
 			return c.JSON(http.StatusNotFound, jsonHTTPResponse{false, err.Error()})
 		}
 
-		if username == "" {
+		if username == "" || !usernameRegexp.MatchString(username) {
 			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid username"})
 		} else {
 			user.Username = username
@@ -261,7 +275,7 @@ func CreateUser(db store.IStore) echo.HandlerFunc {
 		password := data["password"].(string)
 		admin := data["admin"].(bool)
 
-		if username == "" {
+		if username == "" || !usernameRegexp.MatchString(username) {
 			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid username"})
 		} else {
 			user.Username = username
@@ -303,6 +317,10 @@ func RemoveUser(db store.IStore) echo.HandlerFunc {
 
 		username := data["username"].(string)
 
+		if !usernameRegexp.MatchString(username) {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid username"})
+		}
+
 		if username == currentUser(c) {
 			return c.JSON(http.StatusForbidden, jsonHTTPResponse{false, "User cannot delete itself"})
 		}
@@ -357,6 +375,11 @@ func GetClient(db store.IStore) echo.HandlerFunc {
 	return func(c echo.Context) error {
 
 		clientID := c.Param("id")
+
+		if _, err := xid.FromString(clientID); err != nil {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid client ID"})
+		}
+
 		qrCodeSettings := model.QRCodeSettings{
 			Enabled:       true,
 			IncludeDNS:    true,
@@ -485,6 +508,10 @@ func EmailClient(db store.IStore, mailer emailer.Emailer, emailSubject, emailCon
 		c.Bind(&payload)
 		// TODO validate email
 
+		if _, err := xid.FromString(payload.ID); err != nil {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid client ID"})
+		}
+
 		qrCodeSettings := model.QRCodeSettings{
 			Enabled:       true,
 			IncludeDNS:    true,
@@ -536,6 +563,10 @@ func UpdateClient(db store.IStore) echo.HandlerFunc {
 		var _client model.Client
 		c.Bind(&_client)
 
+		if _, err := xid.FromString(_client.ID); err != nil {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid client ID"})
+		}
+
 		// validate client existence
 		clientData, err := db.GetClientByID(_client.ID, model.QRCodeSettings{Enabled: false})
 		if err != nil {
@@ -614,6 +645,7 @@ func UpdateClient(db store.IStore) echo.HandlerFunc {
 		client.AllocatedIPs = _client.AllocatedIPs
 		client.AllowedIPs = _client.AllowedIPs
 		client.ExtraAllowedIPs = _client.ExtraAllowedIPs
+		client.Endpoint = _client.Endpoint
 		client.PublicKey = _client.PublicKey
 		client.PresharedKey = _client.PresharedKey
 		client.UpdatedAt = time.Now().UTC()
@@ -642,6 +674,10 @@ func SetClientStatus(db store.IStore) echo.HandlerFunc {
 		clientID := data["id"].(string)
 		status := data["status"].(bool)
 
+		if _, err := xid.FromString(clientID); err != nil {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid client ID"})
+		}
+
 		clientData, err := db.GetClientByID(clientID, model.QRCodeSettings{Enabled: false})
 		if err != nil {
 			return c.JSON(http.StatusNotFound, jsonHTTPResponse{false, err.Error()})
@@ -667,6 +703,10 @@ func DownloadClient(db store.IStore) echo.HandlerFunc {
 			return c.JSON(http.StatusNotFound, jsonHTTPResponse{false, "Missing clientid parameter"})
 		}
 
+		if _, err := xid.FromString(clientID); err != nil {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid client ID"})
+		}
+
 		clientData, err := db.GetClientByID(clientID, model.QRCodeSettings{Enabled: false})
 		if err != nil {
 			log.Errorf("Cannot generate client id %s config file for downloading: %v", clientID, err)
@@ -689,7 +729,7 @@ func DownloadClient(db store.IStore) echo.HandlerFunc {
 
 		// set response header for downloading
 		c.Response().Header().Set(echo.HeaderContentDisposition, fmt.Sprintf("attachment; filename=%s.conf", clientData.Client.Name))
-		return c.Stream(http.StatusOK, "text/plain", reader)
+		return c.Stream(http.StatusOK, "text/conf", reader)
 	}
 }
 
@@ -700,6 +740,10 @@ func RemoveClient(db store.IStore) echo.HandlerFunc {
 		client := new(model.Client)
 		c.Bind(client)
 
+		if _, err := xid.FromString(client.ID); err != nil {
+			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Please provide a valid client ID"})
+		}
+
 		// delete client from database
 
 		if err := db.DeleteClient(client.ID); err != nil {
diff --git a/main.go b/main.go
index 74fcb0f..fd4bc90 100644
--- a/main.go
+++ b/main.go
@@ -4,9 +4,6 @@ import (
 	"embed"
 	"flag"
 	"fmt"
-	"github.com/labstack/echo/v4"
-	"github.com/labstack/gommon/log"
-	"github.com/ngoduykhanh/wireguard-ui/store"
 	"io/fs"
 	"net/http"
 	"os"
@@ -15,6 +12,10 @@ import (
 	"net"
 	"syscall"
 
+	"github.com/labstack/echo/v4"
+	"github.com/labstack/gommon/log"
+	"github.com/ngoduykhanh/wireguard-ui/store"
+
 	"github.com/ngoduykhanh/wireguard-ui/emailer"
 	"github.com/ngoduykhanh/wireguard-ui/handler"
 	"github.com/ngoduykhanh/wireguard-ui/router"
@@ -73,16 +74,41 @@ func init() {
 	flag.StringVar(&flagSmtpHostname, "smtp-hostname", util.LookupEnvOrString("SMTP_HOSTNAME", flagSmtpHostname), "SMTP Hostname")
 	flag.IntVar(&flagSmtpPort, "smtp-port", util.LookupEnvOrInt("SMTP_PORT", flagSmtpPort), "SMTP Port")
 	flag.StringVar(&flagSmtpUsername, "smtp-username", util.LookupEnvOrString("SMTP_USERNAME", flagSmtpUsername), "SMTP Username")
-	flag.StringVar(&flagSmtpPassword, "smtp-password", util.LookupEnvOrString("SMTP_PASSWORD", flagSmtpPassword), "SMTP Password")
 	flag.BoolVar(&flagSmtpNoTLSCheck, "smtp-no-tls-check", util.LookupEnvOrBool("SMTP_NO_TLS_CHECK", flagSmtpNoTLSCheck), "Disable TLS verification for SMTP. This is potentially dangerous.")
 	flag.StringVar(&flagSmtpEncryption, "smtp-encryption", util.LookupEnvOrString("SMTP_ENCRYPTION", flagSmtpEncryption), "SMTP Encryption : NONE, SSL, SSLTLS, TLS or STARTTLS (by default)")
 	flag.StringVar(&flagSmtpAuthType, "smtp-auth-type", util.LookupEnvOrString("SMTP_AUTH_TYPE", flagSmtpAuthType), "SMTP Auth Type : PLAIN, LOGIN or NONE.")
-	flag.StringVar(&flagSendgridApiKey, "sendgrid-api-key", util.LookupEnvOrString("SENDGRID_API_KEY", flagSendgridApiKey), "Your sendgrid api key.")
 	flag.StringVar(&flagEmailFrom, "email-from", util.LookupEnvOrString("EMAIL_FROM_ADDRESS", flagEmailFrom), "'From' email address.")
 	flag.StringVar(&flagEmailFromName, "email-from-name", util.LookupEnvOrString("EMAIL_FROM_NAME", flagEmailFromName), "'From' email name.")
-	flag.StringVar(&flagSessionSecret, "session-secret", util.LookupEnvOrString("SESSION_SECRET", flagSessionSecret), "The key used to encrypt session cookies.")
 	flag.StringVar(&flagWgConfTemplate, "wg-conf-template", util.LookupEnvOrString("WG_CONF_TEMPLATE", flagWgConfTemplate), "Path to custom wg.conf template.")
 	flag.StringVar(&flagBasePath, "base-path", util.LookupEnvOrString("BASE_PATH", flagBasePath), "The base path of the URL")
+
+	var (
+		smtpPasswordLookup  = util.LookupEnvOrString("SMTP_PASSWORD", flagSmtpPassword)
+		sengridApiKeyLookup = util.LookupEnvOrString("SENDGRID_API_KEY", flagSendgridApiKey)
+		sessionSecretLookup = util.LookupEnvOrString("SESSION_SECRET", flagSessionSecret)
+	)
+
+	// check empty smtpPassword env var
+	if smtpPasswordLookup != "" {
+		flag.StringVar(&flagSmtpPassword, "smtp-password", smtpPasswordLookup, "SMTP Password")
+	} else {
+		flag.StringVar(&flagSmtpPassword, "smtp-password", util.LookupEnvOrFile("SMTP_PASSWORD_FILE", flagSmtpPassword), "SMTP Password File")
+	}
+
+	// check empty sengridApiKey env var
+	if sengridApiKeyLookup != "" {
+		flag.StringVar(&flagSendgridApiKey, "sendgrid-api-key", sengridApiKeyLookup, "Your sendgrid api key.")
+	} else {
+		flag.StringVar(&flagSendgridApiKey, "sendgrid-api-key", util.LookupEnvOrFile("SENDGRID_API_KEY_FILE", flagSendgridApiKey), "File containing your sendgrid api key.")
+	}
+
+	// check empty sessionSecret env var
+	if sessionSecretLookup != "" {
+		flag.StringVar(&flagSessionSecret, "session-secret", sessionSecretLookup, "The key used to encrypt session cookies.")
+	} else {
+		flag.StringVar(&flagSessionSecret, "session-secret", util.LookupEnvOrFile("SESSION_SECRET_FILE", flagSessionSecret), "File containing the key used to encrypt session cookies.")
+	}
+
 	flag.Parse()
 
 	// update runtime config
@@ -149,15 +175,19 @@ func main() {
 
 	app.GET(util.BasePath, handler.WireGuardClients(db), handler.ValidSession)
 
+	// Important: Make sure that all non-GET routes check the request content type using handler.ContentTypeJson to
+	// mitigate CSRF attacks. This is effective, because browsers don't allow setting the Content-Type header on
+	// cross-origin requests.
+
 	if !util.DisableLogin {
 		app.GET(util.BasePath+"/login", handler.LoginPage())
-		app.POST(util.BasePath+"/login", handler.Login(db))
+		app.POST(util.BasePath+"/login", handler.Login(db), handler.ContentTypeJson)
 		app.GET(util.BasePath+"/logout", handler.Logout(), handler.ValidSession)
 		app.GET(util.BasePath+"/profile", handler.LoadProfile(db), handler.ValidSession)
 		app.GET(util.BasePath+"/users-settings", handler.UsersSettings(db), handler.ValidSession, handler.NeedsAdmin)
-		app.POST(util.BasePath+"/update-user", handler.UpdateUser(db), handler.ValidSession)
-		app.POST(util.BasePath+"/create-user", handler.CreateUser(db), handler.ValidSession, handler.NeedsAdmin)
-		app.POST(util.BasePath+"/remove-user", handler.RemoveUser(db), handler.ValidSession, handler.NeedsAdmin)
+		app.POST(util.BasePath+"/update-user", handler.UpdateUser(db), handler.ValidSession, handler.ContentTypeJson)
+		app.POST(util.BasePath+"/create-user", handler.CreateUser(db), handler.ValidSession, handler.ContentTypeJson, handler.NeedsAdmin)
+		app.POST(util.BasePath+"/remove-user", handler.RemoveUser(db), handler.ValidSession, handler.ContentTypeJson, handler.NeedsAdmin)
 		app.GET(util.BasePath+"/getusers", handler.GetUsers(db), handler.ValidSession, handler.NeedsAdmin)
 		app.GET(util.BasePath+"/api/user/:username", handler.GetUser(db), handler.ValidSession)
 	}
diff --git a/model/client.go b/model/client.go
index be5fa76..95342f0 100644
--- a/model/client.go
+++ b/model/client.go
@@ -15,6 +15,7 @@ type Client struct {
 	AllocatedIPs    []string  `json:"allocated_ips"`
 	AllowedIPs      []string  `json:"allowed_ips"`
 	ExtraAllowedIPs []string  `json:"extra_allowed_ips"`
+	Endpoint        string    `json:"endpoint"`
 	UseServerDNS    bool      `json:"use_server_dns"`
 	Enabled         bool      `json:"enabled"`
 	CreatedAt       time.Time `json:"created_at"`
diff --git a/model/server.go b/model/server.go
index 0784eea..0aa804f 100644
--- a/model/server.go
+++ b/model/server.go
@@ -23,5 +23,6 @@ type ServerInterface struct {
 	ListenPort int       `json:"listen_port,string"` // ,string to get listen_port string input as int
 	UpdatedAt  time.Time `json:"updated_at"`
 	PostUp     string    `json:"post_up"`
+	PreDown    string    `json:"pre_down"`
 	PostDown   string    `json:"post_down"`
 }
diff --git a/model/wake_on_lan_host.go b/model/wake_on_lan_host.go
index 2d1ab73..73966f0 100644
--- a/model/wake_on_lan_host.go
+++ b/model/wake_on_lan_host.go
@@ -2,6 +2,7 @@ package model
 
 import (
 	"errors"
+	"net"
 	"strings"
 	"time"
 )
@@ -18,7 +19,13 @@ func (host WakeOnLanHost) ResolveResourceName() (string, error) {
 		return "", errors.New("mac Address is Empty")
 	}
 	resourceName = strings.ToUpper(resourceName)
-	return strings.ReplaceAll(resourceName, ":", "-"), nil
+	resourceName = strings.ReplaceAll(resourceName, ":", "-")
+
+	if _, err := net.ParseMAC(resourceName); err != nil {
+		return "", errors.New("invalid mac address")
+	}
+
+	return resourceName, nil
 }
 
 const WakeOnLanHostCollectionName = "wake_on_lan_hosts"
diff --git a/store/jsondb/jsondb.go b/store/jsondb/jsondb.go
index 0b674b0..757ccdc 100644
--- a/store/jsondb/jsondb.go
+++ b/store/jsondb/jsondb.go
@@ -38,12 +38,12 @@ func New(dbPath string) (*JsonDB, error) {
 func (o *JsonDB) Init() error {
 	var clientPath string = path.Join(o.dbPath, "clients")
 	var serverPath string = path.Join(o.dbPath, "server")
+	var userPath string = path.Join(o.dbPath, "users")
 	var wakeOnLanHostsPath string = path.Join(o.dbPath, "wake_on_lan_hosts")
 	var serverInterfacePath string = path.Join(serverPath, "interfaces.json")
 	var serverKeyPairPath string = path.Join(serverPath, "keypair.json")
 	var globalSettingPath string = path.Join(serverPath, "global_settings.json")
 	var hashesPath string = path.Join(serverPath, "hashes.json")
-	var userPath string = path.Join(serverPath, "users.json")
 
 	// create directories if they do not exist
 	if _, err := os.Stat(clientPath); os.IsNotExist(err) {
@@ -52,12 +52,12 @@ func (o *JsonDB) Init() error {
 	if _, err := os.Stat(serverPath); os.IsNotExist(err) {
 		os.MkdirAll(serverPath, os.ModePerm)
 	}
-	if _, err := os.Stat(wakeOnLanHostsPath); os.IsNotExist(err) {
-		os.MkdirAll(wakeOnLanHostsPath, os.ModePerm)
-	}
 	if _, err := os.Stat(userPath); os.IsNotExist(err) {
 		os.MkdirAll(userPath, os.ModePerm)
 	}
+	if _, err := os.Stat(wakeOnLanHostsPath); os.IsNotExist(err) {
+		os.MkdirAll(wakeOnLanHostsPath, os.ModePerm)
+	}
 
 	// server's interface
 	if _, err := os.Stat(serverInterfacePath); os.IsNotExist(err) {
@@ -68,7 +68,10 @@ func (o *JsonDB) Init() error {
 		serverInterface.PostDown = util.LookupEnvOrString(util.ServerPostDownScriptEnvVar, "")
 		serverInterface.UpdatedAt = time.Now().UTC()
 		o.conn.Write("server", "interfaces", serverInterface)
-		os.Chmod(serverInterfacePath, 0600)
+		err := util.ManagePerms(serverInterfacePath)
+		if err != nil {
+			return err
+		}
 	}
 
 	// server's key pair
@@ -83,7 +86,10 @@ func (o *JsonDB) Init() error {
 		serverKeyPair.PublicKey = key.PublicKey().String()
 		serverKeyPair.UpdatedAt = time.Now().UTC()
 		o.conn.Write("server", "keypair", serverKeyPair)
-		os.Chmod(serverKeyPairPath, 0600)
+		err = util.ManagePerms(serverKeyPairPath)
+		if err != nil {
+			return err
+		}
 	}
 
 	// global settings
@@ -108,7 +114,10 @@ func (o *JsonDB) Init() error {
 		globalSetting.ConfigFilePath = util.LookupEnvOrString(util.ConfigFilePathEnvVar, util.DefaultConfigFilePath)
 		globalSetting.UpdatedAt = time.Now().UTC()
 		o.conn.Write("server", "global_settings", globalSetting)
-		os.Chmod(globalSettingPath, 0600)
+		err := util.ManagePerms(globalSettingPath)
+		if err != nil {
+			return err
+		}
 	}
 
 	// hashes
@@ -117,7 +126,10 @@ func (o *JsonDB) Init() error {
 		clientServerHashes.Client = "none"
 		clientServerHashes.Server = "none"
 		o.conn.Write("server", "hashes", clientServerHashes)
-		os.Chmod(hashesPath, 0600)
+		err := util.ManagePerms(hashesPath)
+		if err != nil {
+			return err
+		}
 	}
 
 	// user info
@@ -128,26 +140,30 @@ func (o *JsonDB) Init() error {
 		user.Admin = util.DefaultIsAdmin
 		user.PasswordHash = util.LookupEnvOrString(util.PasswordHashEnvVar, "")
 		if user.PasswordHash == "" {
-			plaintext := util.LookupEnvOrString(util.PasswordEnvVar, util.DefaultPassword)
-			hash, err := util.HashPassword(plaintext)
-			if err != nil {
-				return err
+			user.PasswordHash = util.LookupEnvOrFile(util.PasswordHashFileEnvVar, "")
+			if user.PasswordHash == "" {
+				plaintext := util.LookupEnvOrString(util.PasswordEnvVar, util.DefaultPassword)
+				if plaintext == util.DefaultPassword {
+					plaintext = util.LookupEnvOrFile(util.PasswordFileEnvVar, util.DefaultPassword)
+				}
+				hash, err := util.HashPassword(plaintext)
+				if err != nil {
+					return err
+				}
+				user.PasswordHash = hash
 			}
-			user.PasswordHash = hash
 		}
+
 		o.conn.Write("users", user.Username, user)
-		os.Chmod(path.Join(path.Join(o.dbPath, "users"), user.Username+".json"), 0600)
+		err = util.ManagePerms(path.Join(path.Join(o.dbPath, "users"), user.Username+".json"))
+		if err != nil {
+			return err
+		}
 	}
 
 	return nil
 }
 
-// GetUser func to query user info from the database
-func (o *JsonDB) GetUser() (model.User, error) {
-	user := model.User{}
-	return user, o.conn.Read("server", "users", &user)
-}
-
 // GetUsers func to get all users from the database
 func (o *JsonDB) GetUsers() ([]model.User, error) {
 	var users []model.User
@@ -182,7 +198,10 @@ func (o *JsonDB) GetUserByName(username string) (model.User, error) {
 func (o *JsonDB) SaveUser(user model.User) error {
 	userPath := path.Join(path.Join(o.dbPath, "users"), user.Username+".json")
 	output := o.conn.Write("users", user.Username, user)
-	os.Chmod(userPath, 0600)
+	err := util.ManagePerms(userPath)
+	if err != nil {
+		return err
+	}
 	return output
 }
 
@@ -295,7 +314,10 @@ func (o *JsonDB) GetClientByID(clientID string, qrCodeSettings model.QRCodeSetti
 func (o *JsonDB) SaveClient(client model.Client) error {
 	clientPath := path.Join(path.Join(o.dbPath, "clients"), client.ID+".json")
 	output := o.conn.Write("clients", client.ID, client)
-	os.Chmod(clientPath, 0600)
+	err := util.ManagePerms(clientPath)
+	if err != nil {
+		return err
+	}
 	return output
 }
 
@@ -306,21 +328,30 @@ func (o *JsonDB) DeleteClient(clientID string) error {
 func (o *JsonDB) SaveServerInterface(serverInterface model.ServerInterface) error {
 	serverInterfacePath := path.Join(path.Join(o.dbPath, "server"), "interfaces.json")
 	output := o.conn.Write("server", "interfaces", serverInterface)
-	os.Chmod(serverInterfacePath, 0600)
+	err := util.ManagePerms(serverInterfacePath)
+	if err != nil {
+		return err
+	}
 	return output
 }
 
 func (o *JsonDB) SaveServerKeyPair(serverKeyPair model.ServerKeypair) error {
 	serverKeyPairPath := path.Join(path.Join(o.dbPath, "server"), "keypair.json")
 	output := o.conn.Write("server", "keypair", serverKeyPair)
-	os.Chmod(serverKeyPairPath, 0600)
+	err := util.ManagePerms(serverKeyPairPath)
+	if err != nil {
+		return err
+	}
 	return output
 }
 
 func (o *JsonDB) SaveGlobalSettings(globalSettings model.GlobalSetting) error {
 	globalSettingsPath := path.Join(path.Join(o.dbPath, "server"), "global_settings.json")
 	output := o.conn.Write("server", "global_settings", globalSettings)
-	os.Chmod(globalSettingsPath, 0600)
+	err := util.ManagePerms(globalSettingsPath)
+	if err != nil {
+		return err
+	}
 	return output
 }
 
@@ -336,6 +367,9 @@ func (o *JsonDB) GetHashes() (model.ClientServerHashes, error) {
 func (o *JsonDB) SaveHashes(hashes model.ClientServerHashes) error {
 	hashesPath := path.Join(path.Join(o.dbPath, "server"), "hashes.json")
 	output := o.conn.Write("server", "hashes", hashes)
-	os.Chmod(hashesPath, 0600)
+	err := util.ManagePerms(hashesPath)
+	if err != nil {
+		return err
+	}
 	return output
 }
diff --git a/store/jsondb/jsondb_wake_on_lan.go b/store/jsondb/jsondb_wake_on_lan.go
index a0ee935..661ba05 100644
--- a/store/jsondb/jsondb_wake_on_lan.go
+++ b/store/jsondb/jsondb_wake_on_lan.go
@@ -3,10 +3,10 @@ package jsondb
 import (
 	"encoding/json"
 	"fmt"
-	"os"
 	"path"
 
 	"github.com/ngoduykhanh/wireguard-ui/model"
+	"github.com/ngoduykhanh/wireguard-ui/util"
 )
 
 func (o *JsonDB) GetWakeOnLanHosts() ([]model.WakeOnLanHost, error) {
@@ -70,7 +70,11 @@ func (o *JsonDB) SaveWakeOnLanHost(host model.WakeOnLanHost) error {
 
 	wakeOnLanHostPath := path.Join(path.Join(o.dbPath, model.WakeOnLanHostCollectionName), resourceName+".json")
 	output := o.conn.Write(model.WakeOnLanHostCollectionName, resourceName, host)
-	os.Chmod(wakeOnLanHostPath, 0600)
+	err = util.ManagePerms(wakeOnLanHostPath)
+	if err != nil {
+		return err
+	}
+
 	return output
 
 }
diff --git a/templates/base.html b/templates/base.html
index 0865ff3..c2fa367 100644
--- a/templates/base.html
+++ b/templates/base.html
@@ -232,6 +232,10 @@
                                 </label>
                                 <input type="text" data-role="tagsinput" class="form-control" id="client_extra_allowed_ips" value="{{ StringsJoin .client_defaults.ExtraAllowedIps "," }}">
                             </div>
+                            <div class="form-group">
+                                <label for="client_endpoint" class="control-label">Endpoint</label>
+                                <input type="text" class="form-control" id="client_endpoint" name="client_endpoint">
+                            </div>
                             <div class="form-group">
                                 <div class="icheck-primary d-inline">
                                     <input type="checkbox" id="use_server_dns" {{ if .client_defaults.UseServerDNS }}checked{{ end }}>
@@ -413,6 +417,7 @@
             const email = $("#client_email").val();
             const allocated_ips = $("#client_allocated_ips").val().split(",");
             const allowed_ips = $("#client_allowed_ips").val().split(",");
+            const endpoint = $("#client_endpoint").val();
             let use_server_dns = false;
             let extra_allowed_ips = [];
 
@@ -434,7 +439,7 @@
             const preshared_key = $("#client_preshared_key").val();
 
             const data = {"name": name, "email": email, "allocated_ips": allocated_ips, "allowed_ips": allowed_ips,
-                "extra_allowed_ips": extra_allowed_ips, "use_server_dns": use_server_dns, "enabled": enabled,
+                "extra_allowed_ips": extra_allowed_ips, "endpoint": endpoint, "use_server_dns": use_server_dns, "enabled": enabled,
                 "public_key": public_key, "preshared_key": preshared_key};
 
             $.ajax({
@@ -492,6 +497,7 @@
             'defaultText': 'Add More',
             'removeWithBackspace': true,
             'minChars': 0,
+            'minInputWidth': '100%',
             'placeholderColor': '#666666'
         });
 
@@ -503,6 +509,7 @@
             'defaultText': 'Add More',
             'removeWithBackspace': true,
             'minChars': 0,
+            'minInputWidth': '100%',
             'placeholderColor': '#666666'
         });
 
@@ -513,6 +520,7 @@
             'defaultText': 'Add More',
             'removeWithBackspace': true,
             'minChars': 0,
+            'minInputWidth': '100%',
             'placeholderColor': '#666666'
         });
 
diff --git a/templates/clients.html b/templates/clients.html
index bcd5855..8b4e4ab 100644
--- a/templates/clients.html
+++ b/templates/clients.html
@@ -113,6 +113,10 @@ Wireguard Clients
                         <input type="text" data-role="tagsinput" class="form-control"
                                id="_client_extra_allowed_ips">
                     </div>
+                    <div class="form-group">
+                        <label for="_client_endpoint" class="control-label">Endpoint</label>
+                        <input type="text" class="form-control" id="_client_endpoint" name="client_endpoint">
+                    </div>
                     <div class="form-group">
                         <div class="icheck-primary d-inline">
                             <input type="checkbox" id="_use_server_dns">
@@ -423,6 +427,7 @@ Wireguard Clients
                     'defaultText': 'Add More',
                     'removeWithBackspace': true,
                     'minChars': 0,
+                    'minInputWidth': '100%',
                     'placeholderColor': '#666666'
                 });
 
@@ -434,6 +439,7 @@ Wireguard Clients
                     'defaultText': 'Add More',
                     'removeWithBackspace': true,
                     'minChars': 0,
+                    'minInputWidth': '100%',
                     'placeholderColor': '#666666'
                 });
 
@@ -444,6 +450,7 @@ Wireguard Clients
                     'defaultText': 'Add More',
                     'removeWithBackspace' : true,
                     'minChars': 0,
+                    'minInputWidth': '100%',
                     'placeholderColor': '#666666'
                 })
 
@@ -477,6 +484,8 @@ Wireguard Clients
                             modal.find("#_client_extra_allowed_ips").addTag(obj);
                         });
 
+                        modal.find("#_client_endpoint").val(client.endpoint);
+
                         modal.find("#_use_server_dns").prop("checked", client.use_server_dns);
                         modal.find("#_enabled").prop("checked", client.enabled);
 
@@ -564,6 +573,8 @@ Wireguard Clients
                 extra_allowed_ips = $("#_client_extra_allowed_ips").val().split(",");
             }
 
+            const endpoint = $("#_client_endpoint").val();
+
             if ($("#_use_server_dns").is(':checked')){
                 use_server_dns = true;
             }
@@ -575,7 +586,8 @@ Wireguard Clients
             }
 
             const data = {"id": client_id, "name": name, "email": email, "allocated_ips": allocated_ips,
-                "allowed_ips": allowed_ips, "extra_allowed_ips": extra_allowed_ips, "use_server_dns": use_server_dns, "enabled": enabled, "public_key": public_key, "preshared_key": preshared_key};
+                "allowed_ips": allowed_ips, "extra_allowed_ips": extra_allowed_ips, "endpoint": endpoint,
+                "use_server_dns": use_server_dns, "enabled": enabled, "public_key": public_key, "preshared_key": preshared_key};
 
             $.ajax({
                 cache: false,
diff --git a/templates/global_settings.html b/templates/global_settings.html
index cafb630..73b3c93 100644
--- a/templates/global_settings.html
+++ b/templates/global_settings.html
@@ -203,6 +203,7 @@ Global Settings
             'defaultText': 'Add More',
             'removeWithBackspace': true,
             'minChars': 0,
+            'minInputWidth': '100%',
             'placeholderColor': '#666666'
         });
 
diff --git a/templates/server.html b/templates/server.html
index 366d301..e1116a6 100644
--- a/templates/server.html
+++ b/templates/server.html
@@ -42,6 +42,12 @@ Wireguard Server Settings
                                 <input type="text" class="form-control" id="post_up" name="post_up"
                                        placeholder="Post Up Script" value="{{ .serverInterface.PostUp }}">
                             </div>
+                            <div class="form-group">
+                                <label for="pre_down">Pre Down Script</label>
+                                <input type="text" class="form-control" id="pre_down" name="pre_down"
+                                       placeholder="Pre Down Script" value="{{ .serverInterface.PreDown }}">
+                            </div>
+
                             <div class="form-group">
                                 <label for="post_down">Post Down Script</label>
                                 <input type="text" class="form-control" id="post_down" name="post_down"
@@ -130,8 +136,9 @@ Wireguard Server Settings
             const addresses = $("#addresses").val().split(",");
             const listen_port = $("#listen_port").val();
             const post_up = $("#post_up").val();
+            const pre_down = $("#pre_down").val();
             const post_down = $("#post_down").val();
-            const data = {"addresses": addresses, "listen_port": listen_port, "post_up": post_up, "post_down": post_down};
+            const data = {"addresses": addresses, "listen_port": listen_port, "post_up": post_up, "pre_down": pre_down, "post_down": post_down};
 
             $.ajax({
                 cache: false,
@@ -160,6 +167,7 @@ Wireguard Server Settings
             'defaultText': 'Add More',
             'removeWithBackspace': true,
             'minChars': 0,
+            'minInputWidth': '100%',
             'placeholderColor': '#666666'
         });
 
diff --git a/templates/wg.conf b/templates/wg.conf
index 81893a8..9269912 100644
--- a/templates/wg.conf
+++ b/templates/wg.conf
@@ -9,6 +9,7 @@ ListenPort = {{ .serverConfig.Interface.ListenPort }}
 PrivateKey = {{ .serverConfig.KeyPair.PrivateKey }}
 {{if .globalSettings.MTU}}MTU = {{ .globalSettings.MTU }}{{end}}
 PostUp = {{ .serverConfig.Interface.PostUp }}
+PreDown = {{ .serverConfig.Interface.PreDown }}
 PostDown = {{ .serverConfig.Interface.PostDown }}
 Table = {{ .globalSettings.Table }}
 
@@ -20,6 +21,7 @@ Table = {{ .globalSettings.Table }}
 # Update at:    {{ .Client.UpdatedAt }}
 [Peer]
 PublicKey = {{ .Client.PublicKey }}
-{{if .Client.PresharedKey }}PresharedKey = {{ .Client.PresharedKey }}
-{{end}}AllowedIPs = {{$first :=true}}{{range .Client.AllocatedIPs }}{{if $first}}{{$first = false}}{{else}},{{end}}{{.}}{{end}}{{range .Client.ExtraAllowedIPs }},{{.}}{{end}}
-{{end}}{{end}}
+{{if .Client.PresharedKey }}PresharedKey = {{ .Client.PresharedKey }}{{end}}
+AllowedIPs = {{$first :=true}}{{range .Client.AllocatedIPs }}{{if $first}}{{$first = false}}{{else}},{{end}}{{.}}{{end}}{{range .Client.ExtraAllowedIPs }},{{.}}{{end}}{{end}}
+{{if .Client.Endpoint }}Endpoint = {{ .Client.Endpoint }}{{end}}
+{{end}}
diff --git a/util/config.go b/util/config.go
index 3c3bd18..6d5a8df 100644
--- a/util/config.go
+++ b/util/config.go
@@ -30,12 +30,14 @@ const (
 	DefaultDNS                             = "1.1.1.1"
 	DefaultMTU                             = 1450
 	DefaultPersistentKeepalive             = 15
-	DefaultFirewallMark                    = "0xca6c"  // i.e. 51820
+	DefaultFirewallMark                    = "0xca6c" // i.e. 51820
 	DefaultTable                           = "auto"
 	DefaultConfigFilePath                  = "/etc/wireguard/wg0.conf"
 	UsernameEnvVar                         = "WGUI_USERNAME"
 	PasswordEnvVar                         = "WGUI_PASSWORD"
+	PasswordFileEnvVar                     = "WGUI_PASSWORD_FILE"
 	PasswordHashEnvVar                     = "WGUI_PASSWORD_HASH"
+	PasswordHashFileEnvVar                 = "WGUI_PASSWORD_HASH_FILE"
 	FaviconFilePathEnvVar                  = "WGUI_FAVICON_FILE_PATH"
 	EndpointAddressEnvVar                  = "WGUI_ENDPOINT_ADDRESS"
 	DNSEnvVar                              = "WGUI_DNS"
diff --git a/util/util.go b/util/util.go
index 44f8f01..f455fc8 100644
--- a/util/util.go
+++ b/util/util.go
@@ -1,11 +1,10 @@
 package util
 
 import (
+	"bufio"
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/ngoduykhanh/wireguard-ui/store"
-	"golang.org/x/mod/sumdb/dirhash"
 	"io"
 	"io/fs"
 	"io/ioutil"
@@ -19,6 +18,9 @@ import (
 	"text/template"
 	"time"
 
+	"github.com/ngoduykhanh/wireguard-ui/store"
+	"golang.org/x/mod/sumdb/dirhash"
+
 	externalip "github.com/glendc/go-external-ip"
 	"github.com/labstack/gommon/log"
 	"github.com/ngoduykhanh/wireguard-ui/model"
@@ -466,6 +468,20 @@ func LookupEnvOrStrings(key string, defaultVal []string) []string {
 	return defaultVal
 }
 
+func LookupEnvOrFile(key string, defaultVal string) string {
+	if val, ok := os.LookupEnv(key); ok {
+		if file, err := os.Open(val); err == nil {
+			var content string
+			scanner := bufio.NewScanner(file)
+			for scanner.Scan() {
+				content += scanner.Text()
+			}
+			return content
+		}
+	}
+	return defaultVal
+}
+
 func StringFromEmbedFile(embed fs.FS, filename string) (string, error) {
 	file, err := embed.Open(filename)
 	if err != nil {
@@ -540,3 +556,8 @@ func RandomString(length int) string {
 	}
 	return string(b)
 }
+
+func ManagePerms(path string) error {
+	err := os.Chmod(path, 0600)
+	return err
+}