diff --git a/.env.example b/.env.example
index 19d7c249..f022fab5 100644
--- a/.env.example
+++ b/.env.example
@@ -1,17 +1,14 @@
 # set timezone to get correct log timestamp
 TZ=ETC/UTC
 
-# generate secret with `openssl rand -base64 32`
-GODOXY_API_JWT_SECRET=
-
-# the JWT token time-to-live
-GODOXY_API_JWT_TOKEN_TTL=1h
-
-# API/WebUI login credentials
-# Important: If using OIDC authentication, the API_USER must match the username
-# provided by the OIDC provider.
+# API/WebUI user password login credentials (optional)
+# These fields are not required for OIDC authentication
 GODOXY_API_USER=admin
 GODOXY_API_PASSWORD=password
+# generate secret with `openssl rand -base64 32`
+GODOXY_API_JWT_SECRET=
+# the JWT token time-to-live
+GODOXY_API_JWT_TOKEN_TTL=1h
 
 # OIDC Configuration (optional)
 # Uncomment and configure these values to enable OIDC authentication.
@@ -22,6 +19,21 @@ GODOXY_API_PASSWORD=password
 # GODOXY_OIDC_REDIRECT_URL=https://your-domain/api/auth/callback
 # Comma-separated list of scopes
 # GODOXY_OIDC_SCOPES=openid, profile, email
+#
+# User definitions: Uncomment and configure these values to restrict access to specific users or groups.
+# These two fields act as a logical AND operator. For example, given the following membership:
+#   user1, group1
+#   user2, group1
+#   user3, group2
+#   user1, group2
+# You can allow access to user3 AND all users of group1 by providing:
+#   # GODOXY_OIDC_ALLOWED_USERS=user3
+#   # GODOXY_OIDC_ALLOWED_GROUPS=group1
+#
+# Comma-separated list of allowed users.
+# GODOXY_OIDC_ALLOWED_USERS=user1,user2
+# Optional: Comma-separated list of allowed groups.
+# GODOXY_OIDC_ALLOWED_GROUPS=group1,group2
 
 # Proxy listening address
 GODOXY_HTTP_ADDR=:80
diff --git a/Makefile b/Makefile
index 83b4e26f..4a7942cd 100755
--- a/Makefile
+++ b/Makefile
@@ -39,7 +39,7 @@ profile:
 
 run: build
 	sudo setcap CAP_NET_BIND_SERVICE=+eip bin/godoxy
-	bin/godoxy
+	[ -f .env ] && godotenv -f .env bin/godoxy || bin/godoxy
 
 mtrace:
 	bin/godoxy debug-ls-mtrace > mtrace.json
diff --git a/cmd/main.go b/cmd/main.go
index e2417472..b38fc0ee 100755
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -117,18 +117,13 @@ func main() {
 		return
 	}
 
+	if err := auth.Initialize(); err != nil {
+		logging.Fatal().Err(err).Msg("failed to initialize authentication")
+	}
+
 	cfg.Start()
 	config.WatchChanges()
 
-	if !auth.IsEnabled() {
-		logging.Warn().Msg("authentication is disabled, please set API_JWT_SECRET or OIDC_* to enable authentication")
-	} else {
-		// Initialize authentication providers
-		if err := auth.Initialize(); err != nil {
-			logging.Fatal().Err(err).Msg("Failed to initialize authentication providers")
-		}
-	}
-
 	sig := make(chan os.Signal, 1)
 	signal.Notify(sig, syscall.SIGINT)
 	signal.Notify(sig, syscall.SIGTERM)
diff --git a/internal/api/handler.go b/internal/api/handler.go
index 5e121616..eff102f4 100644
--- a/internal/api/handler.go
+++ b/internal/api/handler.go
@@ -1,45 +1,46 @@
 package api
 
 import (
-	"net"
 	"net/http"
 
 	v1 "github.com/yusing/go-proxy/internal/api/v1"
 	"github.com/yusing/go-proxy/internal/api/v1/auth"
 	"github.com/yusing/go-proxy/internal/api/v1/favicon"
-	. "github.com/yusing/go-proxy/internal/api/v1/utils"
-	"github.com/yusing/go-proxy/internal/common"
 	config "github.com/yusing/go-proxy/internal/config/types"
+	"github.com/yusing/go-proxy/internal/utils/strutils"
 )
 
 type ServeMux struct{ *http.ServeMux }
 
-func (mux ServeMux) HandleFunc(method, endpoint string, handler http.HandlerFunc) {
-	mux.ServeMux.HandleFunc(method+" "+endpoint, checkHost(handler))
+func (mux ServeMux) HandleFunc(methods, endpoint string, handler http.HandlerFunc) {
+	for _, m := range strutils.CommaSeperatedList(methods) {
+		mux.ServeMux.HandleFunc(m+" "+endpoint, handler)
+	}
 }
 
 func NewHandler(cfg config.ConfigInstance) http.Handler {
 	mux := ServeMux{http.NewServeMux()}
 	mux.HandleFunc("GET", "/v1", v1.Index)
 	mux.HandleFunc("GET", "/v1/version", v1.GetVersion)
-	mux.HandleFunc("POST", "/v1/login", auth.UserPassLoginHandler)
-	mux.HandleFunc("GET", "/v1/auth/redirect", auth.AuthRedirectHandler)
-	mux.HandleFunc("GET", "/v1/auth/callback", auth.OIDCCallbackHandler)
-	mux.HandleFunc("GET", "/v1/logout", auth.LogoutHandler)
-	mux.HandleFunc("POST", "/v1/logout", auth.LogoutHandler)
 	mux.HandleFunc("POST", "/v1/reload", useCfg(cfg, v1.Reload))
 	mux.HandleFunc("GET", "/v1/list", auth.RequireAuth(useCfg(cfg, v1.List)))
 	mux.HandleFunc("GET", "/v1/list/{what}", auth.RequireAuth(useCfg(cfg, v1.List)))
 	mux.HandleFunc("GET", "/v1/list/{what}/{which}", auth.RequireAuth(useCfg(cfg, v1.List)))
 	mux.HandleFunc("GET", "/v1/file/{type}/{filename}", auth.RequireAuth(v1.GetFileContent))
-	mux.HandleFunc("POST", "/v1/file/{type}/{filename}", auth.RequireAuth(v1.SetFileContent))
-	mux.HandleFunc("PUT", "/v1/file/{type}/{filename}", auth.RequireAuth(v1.SetFileContent))
+	mux.HandleFunc("POST,PUT", "/v1/file/{type}/{filename}", auth.RequireAuth(v1.SetFileContent))
 	mux.HandleFunc("GET", "/v1/schema/{filename...}", v1.GetSchemaFile)
 	mux.HandleFunc("GET", "/v1/stats", useCfg(cfg, v1.Stats))
 	mux.HandleFunc("GET", "/v1/stats/ws", useCfg(cfg, v1.StatsWS))
 	mux.HandleFunc("GET", "/v1/health/ws", useCfg(cfg, v1.HealthWS))
 	mux.HandleFunc("GET", "/v1/logs/ws", useCfg(cfg, v1.LogsWS()))
 	mux.HandleFunc("GET", "/v1/favicon/{alias}", auth.RequireAuth(favicon.GetFavIcon))
+
+	defaultAuth := auth.GetDefaultAuth()
+	if defaultAuth != nil {
+		mux.HandleFunc("GET", "/v1/auth/redirect", defaultAuth.RedirectLoginPage)
+		mux.HandleFunc("GET,POST", "/v1/auth/callback", defaultAuth.LoginCallbackHandler)
+		mux.HandleFunc("GET,POST", "/v1/auth/logout", auth.LogoutCallbackHandler(defaultAuth))
+	}
 	return mux
 }
 
@@ -48,20 +49,3 @@ func useCfg(cfg config.ConfigInstance, handler func(cfg config.ConfigInstance, w
 		handler(cfg, w, r)
 	}
 }
-
-// allow only requests to API server with localhost.
-func checkHost(f http.HandlerFunc) http.HandlerFunc {
-	if common.IsDebug {
-		return f
-	}
-	return func(w http.ResponseWriter, r *http.Request) {
-		host, _, _ := net.SplitHostPort(r.RemoteAddr)
-		if host != "127.0.0.1" && host != "localhost" && host != "[::1]" {
-			LogWarn(r).Msgf("blocked API request from %s", host)
-			http.Error(w, "forbidden", http.StatusForbidden)
-			return
-		}
-		LogDebug(r).Interface("headers", r.Header).Msg("API request")
-		f(w, r)
-	}
-}
diff --git a/internal/api/v1/auth/auth.go b/internal/api/v1/auth/auth.go
index 532d339b..ed0060e2 100644
--- a/internal/api/v1/auth/auth.go
+++ b/internal/api/v1/auth/auth.go
@@ -1,139 +1,54 @@
 package auth
 
 import (
-	"fmt"
 	"net/http"
-	"time"
 
-	"github.com/golang-jwt/jwt/v5"
 	U "github.com/yusing/go-proxy/internal/api/v1/utils"
 	"github.com/yusing/go-proxy/internal/common"
-	E "github.com/yusing/go-proxy/internal/error"
-	"github.com/yusing/go-proxy/internal/utils/strutils"
+	"github.com/yusing/go-proxy/internal/logging"
 )
 
-type (
-	Credentials struct {
-		Username string `json:"username"`
-		Password string `json:"password"`
-	}
-	Claims struct {
-		Username string `json:"username"`
-		jwt.RegisteredClaims
-	}
-)
+var defaultAuth Provider
 
 // Initialize sets up authentication providers.
 func Initialize() error {
+	if !IsEnabled() {
+		logging.Warn().Msg("authentication is disabled, please set API_JWT_SECRET or OIDC_* to enable authentication")
+		return nil
+	}
+
+	var err error
 	// Initialize OIDC if configured.
 	if common.OIDCIssuerURL != "" {
-		return InitOIDC(
-			common.OIDCIssuerURL,
-			common.OIDCClientID,
-			common.OIDCClientSecret,
-			common.OIDCRedirectURL,
-		)
+		defaultAuth, err = NewOIDCProviderFromEnv()
+	} else {
+		defaultAuth, err = NewUserPassAuthFromEnv()
 	}
-	return nil
+
+	return err
+}
+
+func GetDefaultAuth() Provider {
+	return defaultAuth
 }
 
 func IsEnabled() bool {
-	return common.APIJWTSecret != nil || common.OIDCIssuerURL != ""
+	return common.APIJWTSecret != nil || IsOIDCEnabled()
 }
 
-// AuthRedirectHandler handles redirect to login page or OIDC login base on configuration.
-func AuthRedirectHandler(w http.ResponseWriter, r *http.Request) {
-	switch {
-	case oauthConfig != nil:
-		RedirectOIDC(w, r)
-		return
-	case common.APIJWTSecret != nil:
-		http.Redirect(w, r, "/login", http.StatusTemporaryRedirect)
-		return
-	default:
-		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
-	}
-}
-
-func setAuthenticatedCookie(w http.ResponseWriter, username string) error {
-	expiresAt := time.Now().Add(common.APIJWTTokenTTL)
-	claim := &Claims{
-		Username: username,
-		RegisteredClaims: jwt.RegisteredClaims{
-			ExpiresAt: jwt.NewNumericDate(expiresAt),
-		},
-	}
-	token := jwt.NewWithClaims(jwt.SigningMethodHS512, claim)
-	tokenStr, err := token.SignedString(common.APIJWTSecret)
-	if err != nil {
-		return err
-	}
-	http.SetCookie(w, &http.Cookie{
-		Name:     CookieToken,
-		Value:    tokenStr,
-		Expires:  expiresAt,
-		HttpOnly: true,
-		Secure:   true,
-		SameSite: http.SameSiteStrictMode,
-		Path:     "/",
-	})
-	return nil
-}
-
-// LogoutHandler clear authentication cookie and redirect to login page.
-func LogoutHandler(w http.ResponseWriter, r *http.Request) {
-	http.SetCookie(w, &http.Cookie{
-		Name:     CookieToken,
-		Value:    "",
-		Expires:  time.Unix(0, 0),
-		HttpOnly: true,
-		Secure:   true,
-		SameSite: http.SameSiteStrictMode,
-		Path:     "/",
-	})
-	AuthRedirectHandler(w, r)
+func IsOIDCEnabled() bool {
+	return common.OIDCIssuerURL != ""
 }
 
 func RequireAuth(next http.HandlerFunc) http.HandlerFunc {
 	if IsEnabled() {
 		return func(w http.ResponseWriter, r *http.Request) {
-			if checkToken(w, r) {
+			if err := defaultAuth.CheckToken(r); err != nil {
+				U.RespondError(w, err, http.StatusUnauthorized)
+			} else {
 				next(w, r)
 			}
 		}
 	}
 	return next
 }
-
-func checkToken(w http.ResponseWriter, r *http.Request) (ok bool) {
-	tokenCookie, err := r.Cookie(CookieToken)
-	if err != nil {
-		U.RespondError(w, E.New("missing token"), http.StatusUnauthorized)
-		return false
-	}
-	var claims Claims
-	token, err := jwt.ParseWithClaims(tokenCookie.Value, &claims, func(t *jwt.Token) (interface{}, error) {
-		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
-			return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
-		}
-		return common.APIJWTSecret, nil
-	})
-
-	switch {
-	case err != nil:
-		break
-	case !token.Valid:
-		err = E.New("invalid token")
-	case claims.Username != common.APIUser:
-		err = E.New("username mismatch").Subject(claims.Username)
-	case claims.ExpiresAt.Before(time.Now()):
-		err = E.Errorf("token expired on %s", strutils.FormatTime(claims.ExpiresAt.Time))
-	}
-
-	if err != nil {
-		U.RespondError(w, err, http.StatusForbidden)
-		return false
-	}
-
-	return true
-}
diff --git a/internal/api/v1/auth/cookies.go b/internal/api/v1/auth/cookies.go
deleted file mode 100644
index c6d73862..00000000
--- a/internal/api/v1/auth/cookies.go
+++ /dev/null
@@ -1,6 +0,0 @@
-package auth
-
-const (
-	CookieToken      = "godoxy_token"
-	CookieOauthState = "godoxy_oauth_state"
-)
diff --git a/internal/api/v1/auth/oidc.go b/internal/api/v1/auth/oidc.go
index 3b1886ae..0c96559e 100644
--- a/internal/api/v1/auth/oidc.go
+++ b/internal/api/v1/auth/oidc.go
@@ -2,87 +2,186 @@ package auth
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
 	"fmt"
 	"net/http"
+	"slices"
+	"time"
 
 	"github.com/coreos/go-oidc/v3/oidc"
 	U "github.com/yusing/go-proxy/internal/api/v1/utils"
 	"github.com/yusing/go-proxy/internal/common"
 	E "github.com/yusing/go-proxy/internal/error"
+	CE "github.com/yusing/go-proxy/internal/utils"
 	"github.com/yusing/go-proxy/internal/utils/strutils"
 	"golang.org/x/oauth2"
 )
 
-var (
-	oauthConfig  *oauth2.Config
-	oidcProvider *oidc.Provider
-	oidcVerifier *oidc.IDTokenVerifier
+type OIDCProvider struct {
+	oauthConfig   *oauth2.Config
+	oidcProvider  *oidc.Provider
+	oidcVerifier  *oidc.IDTokenVerifier
+	allowedUsers  []string
+	allowedGroups []string
+	isMiddleware  bool
+}
+
+const CookieOauthState = "godoxy_oidc_state"
+
+const (
+	OIDCMiddlewareCallbackPath = "/auth/callback"
+	OIDCLogoutPath             = "/auth/logout"
 )
 
-// InitOIDC initializes the OIDC provider.
-func InitOIDC(issuerURL, clientID, clientSecret, redirectURL string) error {
-	if issuerURL == "" {
-		return nil // OIDC not configured
+func NewOIDCProvider(issuerURL, clientID, clientSecret, redirectURL string, allowedUsers, allowedGroups []string) (*OIDCProvider, error) {
+	if len(allowedUsers)+len(allowedGroups) == 0 {
+		return nil, errors.New("OIDC users, groups, or both must not be empty")
 	}
 
 	provider, err := oidc.NewProvider(context.Background(), issuerURL)
 	if err != nil {
-		return fmt.Errorf("failed to initialize OIDC provider: %w", err)
+		return nil, fmt.Errorf("failed to initialize OIDC provider: %w", err)
 	}
 
-	oidcProvider = provider
-	oidcVerifier = provider.Verifier(&oidc.Config{
-		ClientID: clientID,
-	})
+	return &OIDCProvider{
+		oauthConfig: &oauth2.Config{
+			ClientID:     clientID,
+			ClientSecret: clientSecret,
+			RedirectURL:  redirectURL,
+			Endpoint:     provider.Endpoint(),
+			Scopes:       strutils.CommaSeperatedList(common.OIDCScopes),
+		},
+		oidcProvider: provider,
+		oidcVerifier: provider.Verifier(&oidc.Config{
+			ClientID: clientID,
+		}),
+		allowedUsers:  allowedUsers,
+		allowedGroups: allowedGroups,
+	}, nil
+}
 
-	oauthConfig = &oauth2.Config{
-		ClientID:     clientID,
-		ClientSecret: clientSecret,
-		RedirectURL:  redirectURL,
-		Endpoint:     provider.Endpoint(),
-		Scopes:       strutils.CommaSeperatedList(common.OIDCScopes),
+// NewOIDCProviderFromEnv creates a new OIDCProvider from environment variables.
+func NewOIDCProviderFromEnv() (*OIDCProvider, error) {
+	return NewOIDCProvider(
+		common.OIDCIssuerURL,
+		common.OIDCClientID,
+		common.OIDCClientSecret,
+		common.OIDCRedirectURL,
+		common.OIDCAllowedUsers,
+		common.OIDCAllowedGroups,
+	)
+}
+
+func (auth *OIDCProvider) TokenCookieName() string {
+	return "godoxy_oidc_token"
+}
+
+func (auth *OIDCProvider) SetIsMiddleware(enabled bool) {
+	auth.isMiddleware = enabled
+}
+
+func (auth *OIDCProvider) SetAllowedUsers(users []string) {
+	auth.allowedUsers = users
+}
+
+func (auth *OIDCProvider) SetAllowedGroups(groups []string) {
+	auth.allowedGroups = groups
+}
+
+func (auth *OIDCProvider) CheckToken(r *http.Request) error {
+	token, err := r.Cookie(auth.TokenCookieName())
+	if err != nil {
+		return ErrMissingToken
 	}
 
+	// checks for Expiry, Audience == ClientID, Issuer, etc.
+	idToken, err := auth.oidcVerifier.Verify(r.Context(), token.Value)
+	if err != nil {
+		return fmt.Errorf("failed to verify ID token: %w: %w", ErrInvalidToken, err)
+	}
+
+	if len(idToken.Audience) == 0 {
+		return ErrInvalidToken
+	}
+
+	var claims struct {
+		Email    string   `json:"email"`
+		Username string   `json:"preferred_username"`
+		Groups   []string `json:"groups"`
+	}
+	if err := idToken.Claims(&claims); err != nil {
+		return fmt.Errorf("failed to parse claims: %w", err)
+	}
+
+	// Logical AND between allowed users and groups.
+	allowedUser := slices.Contains(auth.allowedUsers, claims.Username)
+	allowedGroup := len(CE.Intersect(claims.Groups, auth.allowedGroups)) > 0
+	if !allowedUser && !allowedGroup {
+		return ErrUserNotAllowed.Subject(claims.Username)
+	}
 	return nil
 }
 
+// generateState generates a random string for OIDC state.
+const oidcStateLength = 32
+
+func generateState() (string, error) {
+	b := make([]byte, oidcStateLength)
+	_, err := rand.Read(b)
+	if err != nil {
+		return "", err
+	}
+	return base64.URLEncoding.EncodeToString(b)[:oidcStateLength], nil
+}
+
 // RedirectOIDC initiates the OIDC login flow.
-func RedirectOIDC(w http.ResponseWriter, r *http.Request) {
-	if oauthConfig == nil {
-		U.HandleErr(w, r, E.New("OIDC not configured"), http.StatusNotImplemented)
+func (auth *OIDCProvider) RedirectLoginPage(w http.ResponseWriter, r *http.Request) {
+	state, err := generateState()
+	if err != nil {
+		U.HandleErr(w, r, err, http.StatusInternalServerError)
 		return
 	}
-
-	state := common.GenerateRandomString(32)
 	http.SetCookie(w, &http.Cookie{
 		Name:     CookieOauthState,
 		Value:    state,
 		MaxAge:   300,
 		HttpOnly: true,
-		SameSite: http.SameSiteNoneMode,
+		SameSite: http.SameSiteLaxMode,
 		Secure:   true,
 		Path:     "/",
 	})
 
-	url := oauthConfig.AuthCodeURL(state)
-	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
+	redirURL := auth.oauthConfig.AuthCodeURL(state)
+	if auth.isMiddleware {
+		u, err := r.URL.Parse(redirURL)
+		if err != nil {
+			U.HandleErr(w, r, err, http.StatusInternalServerError)
+			return
+		}
+		q := u.Query()
+		q.Set("redirect_uri", "https://"+r.Host+OIDCMiddlewareCallbackPath+q.Get("redirect_uri"))
+		u.RawQuery = q.Encode()
+		redirURL = u.String()
+	}
+	http.Redirect(w, r, redirURL, http.StatusTemporaryRedirect)
+}
+
+func (auth *OIDCProvider) exchange(r *http.Request) (*oauth2.Token, error) {
+	if auth.isMiddleware {
+		cfg := *auth.oauthConfig
+		cfg.RedirectURL = "https://" + r.Host + OIDCMiddlewareCallbackPath
+		return cfg.Exchange(r.Context(), r.URL.Query().Get("code"))
+	}
+	return auth.oauthConfig.Exchange(r.Context(), r.URL.Query().Get("code"))
 }
 
 // OIDCCallbackHandler handles the OIDC callback.
-func OIDCCallbackHandler(w http.ResponseWriter, r *http.Request) {
-	if oauthConfig == nil {
-		U.HandleErr(w, r, E.New("OIDC not configured"), http.StatusNotImplemented)
-		return
-	}
-
+func (auth *OIDCProvider) LoginCallbackHandler(w http.ResponseWriter, r *http.Request) {
 	// For testing purposes, skip provider verification
 	if common.IsTest {
-		handleTestCallback(w, r)
-		return
-	}
-
-	if oidcProvider == nil {
-		U.HandleErr(w, r, E.New("OIDC not configured"), http.StatusNotImplemented)
+		auth.handleTestCallback(w, r)
 		return
 	}
 
@@ -92,13 +191,13 @@ func OIDCCallbackHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if r.URL.Query().Get("state") != state.Value {
+	query := r.URL.Query()
+	if query.Get("state") != state.Value {
 		U.HandleErr(w, r, E.New("invalid oauth state"), http.StatusBadRequest)
 		return
 	}
 
-	code := r.URL.Query().Get("code")
-	oauth2Token, err := oauthConfig.Exchange(r.Context(), code)
+	oauth2Token, err := auth.exchange(r)
 	if err != nil {
 		U.HandleErr(w, r, fmt.Errorf("failed to exchange token: %w", err), http.StatusInternalServerError)
 		return
@@ -110,32 +209,20 @@ func OIDCCallbackHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	idToken, err := oidcVerifier.Verify(r.Context(), rawIDToken)
+	idToken, err := auth.oidcVerifier.Verify(r.Context(), rawIDToken)
 	if err != nil {
 		U.HandleErr(w, r, fmt.Errorf("failed to verify ID token: %w", err), http.StatusInternalServerError)
 		return
 	}
 
-	var claims struct {
-		Email    string `json:"email"`
-		Username string `json:"preferred_username"`
-	}
-	if err := idToken.Claims(&claims); err != nil {
-		U.HandleErr(w, r, fmt.Errorf("failed to parse claims: %w", err), http.StatusInternalServerError)
-		return
-	}
-
-	if err := setAuthenticatedCookie(w, claims.Username); err != nil {
-		U.HandleErr(w, r, err, http.StatusInternalServerError)
-		return
-	}
+	setTokenCookie(w, r, auth.TokenCookieName(), rawIDToken, time.Until(idToken.Expiry))
 
 	// Redirect to home page
 	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
 }
 
 // handleTestCallback handles OIDC callback in test environment.
-func handleTestCallback(w http.ResponseWriter, r *http.Request) {
+func (auth *OIDCProvider) handleTestCallback(w http.ResponseWriter, r *http.Request) {
 	state, err := r.Cookie(CookieOauthState)
 	if err != nil {
 		U.HandleErr(w, r, E.New("missing state cookie"), http.StatusBadRequest)
@@ -148,10 +235,7 @@ func handleTestCallback(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Create test JWT token
-	if err := setAuthenticatedCookie(w, "test-user"); err != nil {
-		U.HandleErr(w, r, err, http.StatusInternalServerError)
-		return
-	}
+	setTokenCookie(w, r, auth.TokenCookieName(), "test", time.Hour)
 
 	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
 }
diff --git a/internal/api/v1/auth/oidc_test.go b/internal/api/v1/auth/oidc_test.go
index 1e1f986d..d14715ea 100644
--- a/internal/api/v1/auth/oidc_test.go
+++ b/internal/api/v1/auth/oidc_test.go
@@ -1,77 +1,165 @@
 package auth
 
 import (
+	"context"
+	"crypto/rand"
+	"crypto/rsa"
+	"encoding/base64"
+	"encoding/json"
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"time"
 
 	"github.com/coreos/go-oidc/v3/oidc"
+	"github.com/golang-jwt/jwt/v5"
 	"github.com/yusing/go-proxy/internal/common"
+	E "github.com/yusing/go-proxy/internal/error"
 	"golang.org/x/oauth2"
+
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 // setupMockOIDC configures mock OIDC provider for testing.
 func setupMockOIDC(t *testing.T) {
 	t.Helper()
 
-	oauthConfig = &oauth2.Config{
-		ClientID:     "test-client",
-		ClientSecret: "test-secret",
-		RedirectURL:  "http://localhost/callback",
-		Endpoint: oauth2.Endpoint{
-			AuthURL:  "http://mock-provider/auth",
-			TokenURL: "http://mock-provider/token",
+	provider := (&oidc.ProviderConfig{}).NewProvider(context.TODO())
+	defaultAuth = &OIDCProvider{
+		oauthConfig: &oauth2.Config{
+			ClientID:     "test-client",
+			ClientSecret: "test-secret",
+			RedirectURL:  "http://localhost/callback",
+			Endpoint: oauth2.Endpoint{
+				AuthURL:  "http://mock-provider/auth",
+				TokenURL: "http://mock-provider/token",
+			},
+			Scopes: []string{oidc.ScopeOpenID, "profile", "email"},
 		},
-		Scopes: []string{oidc.ScopeOpenID, "profile", "email"},
+		oidcProvider: provider,
+		oidcVerifier: provider.Verifier(&oidc.Config{
+			ClientID: "test-client",
+		}),
+		allowedUsers:  []string{"test-user"},
+		allowedGroups: []string{"test-group1", "test-group2"},
+	}
+}
+
+// discoveryDocument returns a mock OIDC discovery document.
+func discoveryDocument(t *testing.T, server *httptest.Server) map[string]any {
+	t.Helper()
+
+	discovery := map[string]any{
+		"issuer":                 server.URL,
+		"authorization_endpoint": server.URL + "/auth",
+		"token_endpoint":         server.URL + "/token",
+	}
+
+	return discovery
+}
+
+const (
+	keyID    = "test-key-id"
+	clientID = "test-client-id"
+)
+
+type provider struct {
+	ts       *httptest.Server
+	key      *rsa.PrivateKey
+	verifier *oidc.IDTokenVerifier
+}
+
+func (j *provider) SignClaims(t *testing.T, claims jwt.Claims) string {
+	t.Helper()
+
+	token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+	token.Header["kid"] = keyID
+	signed, err := token.SignedString(j.key)
+	ExpectNoError(t, err)
+	return signed
+}
+
+func setupProvider(t *testing.T) *provider {
+	t.Helper()
+
+	// Generate an RSA key pair for the test.
+	privKey, err := rsa.GenerateKey(rand.Reader, 2048)
+	ExpectNoError(t, err)
+
+	// Build the matching public JWK that will be served by the endpoint.
+	jwk := buildRSAJWK(t, &privKey.PublicKey, keyID)
+
+	// Start a test server that serves the JWKS endpoint.
+	ts := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/.well-known/jwks.json":
+			_ = json.NewEncoder(w).Encode(map[string]any{
+				"keys": []any{jwk},
+			})
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	t.Cleanup(ts.Close)
+
+	// Create a test OIDCProvider.
+	providerCtx := oidc.ClientContext(context.Background(), ts.Client())
+	keySet := oidc.NewRemoteKeySet(providerCtx, ts.URL+"/.well-known/jwks.json")
+
+	return &provider{
+		ts:  ts,
+		key: privKey,
+		verifier: oidc.NewVerifier(ts.URL, keySet, &oidc.Config{
+			ClientID: clientID, // matches audience in the token
+		}),
+	}
+}
+
+// buildRSAJWK is a helper to construct a minimal JWK for the JWKS endpoint
+func buildRSAJWK(t *testing.T, pub *rsa.PublicKey, kid string) map[string]any {
+	t.Helper()
+
+	nBytes := pub.N.Bytes()
+	eBytes := []byte{0x01, 0x00, 0x01} // Usually 65537
+
+	return map[string]any{
+		"kty": "RSA",
+		"alg": "RS256",
+		"use": "sig",
+		"kid": kid,
+		"n":   base64.RawURLEncoding.EncodeToString(nBytes),
+		"e":   base64.RawURLEncoding.EncodeToString(eBytes),
 	}
 }
 
 func cleanup() {
-	oauthConfig = nil
-	oidcProvider = nil
-	oidcVerifier = nil
+	defaultAuth = nil
 }
 
 func TestOIDCLoginHandler(t *testing.T) {
 	// Setup
 	common.APIJWTSecret = []byte("test-secret")
-	common.IsTest = true
-	t.Cleanup(func() {
-		cleanup()
-		common.IsTest = false
-	})
+	t.Cleanup(cleanup)
 	setupMockOIDC(t)
 
 	tests := []struct {
-		name           string
-		configureOAuth bool
-		wantStatus     int
-		wantRedirect   bool
+		name         string
+		wantStatus   int
+		wantRedirect bool
 	}{
 		{
-			name:           "Success - Redirects to provider",
-			configureOAuth: true,
-			wantStatus:     http.StatusTemporaryRedirect,
-			wantRedirect:   true,
-		},
-		{
-			name:           "Failure - OIDC not configured",
-			configureOAuth: false,
-			wantStatus:     http.StatusNotImplemented,
-			wantRedirect:   false,
+			name:         "Success - Redirects to provider",
+			wantStatus:   http.StatusTemporaryRedirect,
+			wantRedirect: true,
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if !tt.configureOAuth {
-				oauthConfig = nil
-			}
-
 			req := httptest.NewRequest(http.MethodGet, "/auth/redirect", nil)
 			w := httptest.NewRecorder()
 
-			RedirectOIDC(w, req)
+			defaultAuth.RedirectLoginPage(w, req)
 
 			if got := w.Code; got != tt.wantStatus {
 				t.Errorf("OIDCLoginHandler() status = %v, want %v", got, tt.wantStatus)
@@ -94,110 +182,267 @@ func TestOIDCLoginHandler(t *testing.T) {
 func TestOIDCCallbackHandler(t *testing.T) {
 	// Setup
 	common.APIJWTSecret = []byte("test-secret")
-	common.IsTest = true
-	t.Cleanup(func() {
-		cleanup()
-		common.IsTest = false
-	})
+	t.Cleanup(cleanup)
 	tests := []struct {
-		name           string
-		configureOAuth bool
-		state          string
-		code           string
-		setupMocks     func()
-		wantStatus     int
+		name       string
+		state      string
+		code       string
+		setupMocks bool
+		wantStatus int
 	}{
 		{
-			name:           "Success - Valid callback",
-			configureOAuth: true,
-			state:          "valid-state",
-			code:           "valid-code",
-			setupMocks: func() {
-				setupMockOIDC(t)
-			},
+			name:       "Success - Valid callback",
+			state:      "valid-state",
+			code:       "valid-code",
+			setupMocks: true,
 			wantStatus: http.StatusTemporaryRedirect,
 		},
 		{
-			name:           "Failure - OIDC not configured",
-			configureOAuth: false,
-			wantStatus:     http.StatusNotImplemented,
-		},
-		{
-			name:           "Failure - Missing state",
-			configureOAuth: true,
-			code:           "valid-code",
-			setupMocks: func() {
-				setupMockOIDC(t)
-			},
+			name:       "Failure - Missing state",
+			code:       "valid-code",
+			setupMocks: true,
 			wantStatus: http.StatusBadRequest,
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if tt.setupMocks != nil {
-				tt.setupMocks()
-			}
-
-			if !tt.configureOAuth {
-				oauthConfig = nil
+			if tt.setupMocks {
+				setupMockOIDC(t)
 			}
 
 			req := httptest.NewRequest(http.MethodGet, "/auth/callback?code="+tt.code+"&state="+tt.state, nil)
 			if tt.state != "" {
 				req.AddCookie(&http.Cookie{
-					Name:  "oauth_state",
+					Name:  CookieOauthState,
 					Value: tt.state,
 				})
 			}
 			w := httptest.NewRecorder()
 
-			OIDCCallbackHandler(w, req)
+			defaultAuth.LoginCallbackHandler(w, req)
 
 			if got := w.Code; got != tt.wantStatus {
 				t.Errorf("OIDCCallbackHandler() status = %v, want %v", got, tt.wantStatus)
 			}
 
 			if tt.wantStatus == http.StatusTemporaryRedirect {
-				cookie := w.Header().Get("Set-Cookie")
-				if cookie == "" {
-					t.Error("OIDCCallbackHandler() missing token cookie")
-				}
+				setCookie := E.Must(http.ParseSetCookie(w.Header().Get("Set-Cookie")))
+				ExpectEqual(t, setCookie.Name, defaultAuth.TokenCookieName())
+				ExpectTrue(t, setCookie.Value != "")
+				ExpectEqual(t, setCookie.Path, "/")
+				ExpectEqual(t, setCookie.SameSite, http.SameSiteLaxMode)
+				ExpectEqual(t, setCookie.HttpOnly, true)
 			}
 		})
 	}
 }
 
 func TestInitOIDC(t *testing.T) {
-	common.IsTest = true
-	t.Cleanup(func() {
-		common.IsTest = false
+	setupMockOIDC(t)
+	// Create a test server that serves the discovery document
+	var server *httptest.Server
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		ExpectNoError(t, json.NewEncoder(w).Encode(discoveryDocument(t, server)))
 	})
+	server = httptest.NewServer(mux)
+	t.Cleanup(server.Close)
+	t.Cleanup(cleanup)
+
 	tests := []struct {
-		name         string
-		issuerURL    string
-		clientID     string
-		clientSecret string
-		redirectURL  string
-		wantErr      bool
+		name          string
+		issuerURL     string
+		clientID      string
+		clientSecret  string
+		redirectURL   string
+		allowedUsers  []string
+		allowedGroups []string
+		wantErr       bool
 	}{
 		{
-			name:         "Success - Empty configuration",
+			name:         "Fail - Empty configuration",
 			issuerURL:    "",
 			clientID:     "",
 			clientSecret: "",
 			redirectURL:  "",
+			allowedUsers: nil,
+			wantErr:      true,
+		},
+		{
+			name:         "Success - Valid configuration with users",
+			issuerURL:    server.URL,
+			clientID:     "client_id",
+			clientSecret: "client_secret",
+			redirectURL:  "https://example.com/callback",
+			allowedUsers: []string{"user1", "user2"},
 			wantErr:      false,
 		},
+		{
+			name:          "Success - Valid configuration with groups",
+			issuerURL:     server.URL,
+			clientID:      "client_id",
+			clientSecret:  "client_secret",
+			redirectURL:   "https://example.com/callback",
+			allowedGroups: []string{"group1", "group2"},
+			wantErr:       false,
+		},
+		{
+			name:         "Fail - No allowed users or allowed groups",
+			issuerURL:    "https://example.com",
+			clientID:     "client_id",
+			clientSecret: "client_secret",
+			redirectURL:  "https://example.com/callback",
+			wantErr:      true,
+		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			t.Cleanup(cleanup)
-			err := InitOIDC(tt.issuerURL, tt.clientID, tt.clientSecret, tt.redirectURL)
+			_, err := NewOIDCProvider(tt.issuerURL, tt.clientID, tt.clientSecret, tt.redirectURL, tt.allowedUsers, tt.allowedGroups)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("InitOIDC() error = %v, wantErr %v", err, tt.wantErr)
 			}
 		})
 	}
 }
+
+func TestCheckToken(t *testing.T) {
+	provider := setupProvider(t)
+
+	tests := []struct {
+		name          string
+		allowedUsers  []string
+		allowedGroups []string
+		claims        jwt.Claims
+		wantErr       error
+	}{
+		{
+			name:         "Success - Valid token with allowed user",
+			allowedUsers: []string{"user1"},
+			claims: jwt.MapClaims{
+				"iss":                provider.ts.URL,
+				"aud":                clientID,
+				"exp":                time.Now().Add(time.Hour).Unix(),
+				"preferred_username": "user1",
+				"groups":             []string{"group1"},
+			},
+		},
+		{
+			name:          "Success - Valid token with allowed group",
+			allowedGroups: []string{"group1"},
+			claims: jwt.MapClaims{
+				"iss":                provider.ts.URL,
+				"aud":                clientID,
+				"exp":                time.Now().Add(time.Hour).Unix(),
+				"preferred_username": "user1",
+				"groups":             []string{"group1"},
+			},
+		},
+		{
+			name:         "Success - Server omits groups, but user is allowed",
+			allowedUsers: []string{"user1"},
+			claims: jwt.MapClaims{
+				"iss":                provider.ts.URL,
+				"aud":                clientID,
+				"exp":                time.Now().Add(time.Hour).Unix(),
+				"preferred_username": "user1",
+			},
+		},
+		{
+			name:          "Success - Server omits preferred_username, but group is allowed",
+			allowedGroups: []string{"group1"},
+			claims: jwt.MapClaims{
+				"iss":    provider.ts.URL,
+				"aud":    clientID,
+				"exp":    time.Now().Add(time.Hour).Unix(),
+				"groups": []string{"group1"},
+			},
+		},
+		{
+			name:          "Success - Valid token with allowed user and group",
+			allowedUsers:  []string{"user1"},
+			allowedGroups: []string{"group1"},
+			claims: jwt.MapClaims{
+				"iss":                provider.ts.URL,
+				"aud":                clientID,
+				"exp":                time.Now().Add(time.Hour).Unix(),
+				"preferred_username": "user1",
+				"groups":             []string{"group1"},
+			},
+		},
+		{
+			name:          "Error - User not allowed",
+			allowedUsers:  []string{"user2", "user3"},
+			allowedGroups: []string{"group2", "group3"},
+			claims: jwt.MapClaims{
+				"iss":                provider.ts.URL,
+				"aud":                clientID,
+				"exp":                time.Now().Add(time.Hour).Unix(),
+				"preferred_username": "user1",
+				"groups":             []string{"group1"},
+			},
+			wantErr: ErrUserNotAllowed,
+		},
+		{
+			name: "Error - Server returns incorrect issuer",
+			claims: jwt.MapClaims{
+				"iss":                "https://example.com",
+				"aud":                clientID,
+				"exp":                time.Now().Add(time.Hour).Unix(),
+				"preferred_username": "user1",
+				"groups":             []string{"group1"},
+			},
+			wantErr: ErrInvalidToken,
+		},
+		{
+			name: "Error - Server returns incorrect audience",
+			claims: jwt.MapClaims{
+				"iss":                provider.ts.URL,
+				"aud":                "some-other-audience",
+				"exp":                time.Now().Add(time.Hour).Unix(),
+				"preferred_username": "user1",
+				"groups":             []string{"group1"},
+			},
+			wantErr: ErrInvalidToken,
+		},
+		{
+			name: "Error - Server returns expired token",
+			claims: jwt.MapClaims{
+				"iss":                provider.ts.URL,
+				"aud":                clientID,
+				"exp":                time.Now().Add(-time.Hour).Unix(),
+				"preferred_username": "user1",
+				"groups":             []string{"group1"},
+			},
+			wantErr: ErrInvalidToken,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			// Create the Auth Provider.
+			auth := &OIDCProvider{
+				oidcVerifier:  provider.verifier,
+				allowedUsers:  tc.allowedUsers,
+				allowedGroups: tc.allowedGroups,
+			}
+			// Sign the claims to create a token.
+			signedToken := provider.SignClaims(t, tc.claims)
+			// Craft a test HTTP request that includes the token as a cookie.
+			req := httptest.NewRequest(http.MethodGet, "/", nil)
+			req.AddCookie(&http.Cookie{
+				Name:  auth.TokenCookieName(),
+				Value: signedToken,
+			})
+
+			// Call CheckToken and verify the result.
+			err := auth.CheckToken(req)
+			if tc.wantErr == nil {
+				ExpectNoError(t, err)
+			} else {
+				ExpectError(t, tc.wantErr, err)
+			}
+		})
+	}
+}
diff --git a/internal/api/v1/auth/provider.go b/internal/api/v1/auth/provider.go
new file mode 100644
index 00000000..8ea4d320
--- /dev/null
+++ b/internal/api/v1/auth/provider.go
@@ -0,0 +1,12 @@
+package auth
+
+import (
+	"net/http"
+)
+
+type Provider interface {
+	TokenCookieName() string
+	CheckToken(r *http.Request) error
+	RedirectLoginPage(w http.ResponseWriter, r *http.Request)
+	LoginCallbackHandler(w http.ResponseWriter, r *http.Request)
+}
diff --git a/internal/api/v1/auth/userpass.go b/internal/api/v1/auth/userpass.go
index 6d00e6a7..ae80c1c7 100644
--- a/internal/api/v1/auth/userpass.go
+++ b/internal/api/v1/auth/userpass.go
@@ -1,13 +1,17 @@
 package auth
 
 import (
-	"bytes"
 	"encoding/json"
+	"fmt"
 	"net/http"
+	"time"
 
+	"github.com/golang-jwt/jwt/v5"
 	U "github.com/yusing/go-proxy/internal/api/v1/utils"
 	"github.com/yusing/go-proxy/internal/common"
 	E "github.com/yusing/go-proxy/internal/error"
+	"github.com/yusing/go-proxy/internal/utils/strutils"
+	"golang.org/x/crypto/bcrypt"
 )
 
 var (
@@ -15,31 +19,120 @@ var (
 	ErrInvalidPassword = E.New("invalid password")
 )
 
-func validatePassword(cred *Credentials) error {
-	if cred.Username != common.APIUser {
-		return ErrInvalidUsername.Subject(cred.Username)
+type (
+	UserPassAuth struct {
+		username string
+		pwdHash  []byte
+		secret   []byte
+		tokenTTL time.Duration
 	}
-	if !bytes.Equal(common.HashPassword(cred.Password), common.APIPasswordHash) {
-		return ErrInvalidPassword.Subject(cred.Password)
+	UserPassClaims struct {
+		Username string `json:"username"`
+		jwt.RegisteredClaims
 	}
+)
+
+func NewUserPassAuth(username, password string, secret []byte, tokenTTL time.Duration) (*UserPassAuth, error) {
+	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		return nil, err
+	}
+	return &UserPassAuth{
+		username: username,
+		pwdHash:  hash,
+		secret:   secret,
+		tokenTTL: tokenTTL,
+	}, nil
+}
+
+func NewUserPassAuthFromEnv() (*UserPassAuth, error) {
+	return NewUserPassAuth(
+		common.APIUser,
+		common.APIPassword,
+		common.APIJWTSecret,
+		common.APIJWTTokenTTL,
+	)
+}
+
+func (auth *UserPassAuth) TokenCookieName() string {
+	return "godoxy_token"
+}
+
+func (auth *UserPassAuth) NewToken() (token string, err error) {
+	claim := &UserPassClaims{
+		Username: auth.username,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(auth.tokenTTL)),
+		},
+	}
+	tok := jwt.NewWithClaims(jwt.SigningMethodHS512, claim)
+	token, err = tok.SignedString(auth.secret)
+	if err != nil {
+		return "", err
+	}
+	return token, nil
+}
+
+func (auth *UserPassAuth) CheckToken(r *http.Request) error {
+	jwtCookie, err := r.Cookie(auth.TokenCookieName())
+	if err != nil {
+		return ErrMissingToken
+	}
+	var claims UserPassClaims
+	token, err := jwt.ParseWithClaims(jwtCookie.Value, &claims, func(t *jwt.Token) (interface{}, error) {
+		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
+		}
+		return auth.secret, nil
+	})
+	if err != nil {
+		return err
+	}
+	switch {
+	case !token.Valid:
+		return ErrInvalidToken
+	case claims.Username != auth.username:
+		return ErrUserNotAllowed.Subject(claims.Username)
+	case claims.ExpiresAt.Before(time.Now()):
+		return E.Errorf("token expired on %s", strutils.FormatTime(claims.ExpiresAt.Time))
+	}
+
 	return nil
 }
 
-// UserPassLoginHandler handles user login.
-func UserPassLoginHandler(w http.ResponseWriter, r *http.Request) {
-	var creds Credentials
+func (auth *UserPassAuth) RedirectLoginPage(w http.ResponseWriter, r *http.Request) {
+	http.Redirect(w, r, "/login", http.StatusTemporaryRedirect)
+}
+
+func (auth *UserPassAuth) LoginCallbackHandler(w http.ResponseWriter, r *http.Request) {
+	var creds struct {
+		User string `json:"username"`
+		Pass string `json:"password"`
+	}
 	err := json.NewDecoder(r.Body).Decode(&creds)
 	if err != nil {
 		U.HandleErr(w, r, err, http.StatusBadRequest)
 		return
 	}
-	if err := validatePassword(&creds); err != nil {
+	if err := auth.validatePassword(creds.User, creds.Pass); err != nil {
 		U.HandleErr(w, r, err, http.StatusUnauthorized)
 		return
 	}
-	if err := setAuthenticatedCookie(w, creds.Username); err != nil {
+	token, err := auth.NewToken()
+	if err != nil {
 		U.HandleErr(w, r, err, http.StatusInternalServerError)
 		return
 	}
+	setTokenCookie(w, r, auth.TokenCookieName(), token, auth.tokenTTL)
 	w.WriteHeader(http.StatusOK)
 }
+
+func (auth *UserPassAuth) validatePassword(user, pass string) error {
+	if user != auth.username {
+		return ErrInvalidUsername.Subject(user)
+	}
+	if err := bcrypt.CompareHashAndPassword(auth.pwdHash, []byte(pass)); err != nil {
+		return ErrInvalidPassword.With(err).Subject(pass)
+	}
+	return nil
+}
diff --git a/internal/api/v1/auth/userpass_test.go b/internal/api/v1/auth/userpass_test.go
new file mode 100644
index 00000000..c43360e7
--- /dev/null
+++ b/internal/api/v1/auth/userpass_test.go
@@ -0,0 +1,116 @@
+package auth
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	E "github.com/yusing/go-proxy/internal/error"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+	"golang.org/x/crypto/bcrypt"
+)
+
+func newMockUserPassAuth() *UserPassAuth {
+	return &UserPassAuth{
+		username: "username",
+		pwdHash:  E.Must(bcrypt.GenerateFromPassword([]byte("password"), bcrypt.DefaultCost)),
+		secret:   []byte("abcdefghijklmnopqrstuvwxyz"),
+		tokenTTL: time.Hour,
+	}
+}
+
+func TestUserPassValidateCredentials(t *testing.T) {
+	auth := newMockUserPassAuth()
+	err := auth.validatePassword("username", "password")
+	ExpectNoError(t, err)
+	err = auth.validatePassword("username", "wrong-password")
+	ExpectError(t, ErrInvalidPassword, err)
+	err = auth.validatePassword("wrong-username", "password")
+	ExpectError(t, ErrInvalidUsername, err)
+}
+
+func TestUserPassCheckToken(t *testing.T) {
+	auth := newMockUserPassAuth()
+	token, err := auth.NewToken()
+	ExpectNoError(t, err)
+	tests := []struct {
+		token   string
+		wantErr bool
+	}{
+		{
+			token:   token,
+			wantErr: false,
+		},
+		{
+			token:   "invalid-token",
+			wantErr: true,
+		},
+		{
+			token:   "",
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		req := &http.Request{Header: http.Header{}}
+		if tt.token != "" {
+			req.Header.Set("Cookie", auth.TokenCookieName()+"="+tt.token)
+		}
+		err = auth.CheckToken(req)
+		if tt.wantErr {
+			ExpectTrue(t, err != nil)
+		} else {
+			ExpectNoError(t, err)
+		}
+	}
+}
+
+func TestUserPassLoginCallbackHandler(t *testing.T) {
+	type cred struct {
+		User string `json:"username"`
+		Pass string `json:"password"`
+	}
+	auth := newMockUserPassAuth()
+	tests := []struct {
+		creds   cred
+		wantErr bool
+	}{
+		{
+			creds: cred{
+				User: "username",
+				Pass: "password",
+			},
+			wantErr: false,
+		},
+		{
+			creds: cred{
+				User: "username",
+				Pass: "wrong-password",
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		w := httptest.NewRecorder()
+		req := &http.Request{
+			Host: "app.example.com",
+			Body: io.NopCloser(bytes.NewReader(E.Must(json.Marshal(tt.creds)))),
+		}
+		auth.LoginCallbackHandler(w, req)
+		if tt.wantErr {
+			ExpectEqual(t, w.Code, http.StatusUnauthorized)
+		} else {
+			setCookie := E.Must(http.ParseSetCookie(w.Header().Get("Set-Cookie")))
+			ExpectTrue(t, setCookie.Name == auth.TokenCookieName())
+			ExpectTrue(t, setCookie.Value != "")
+			ExpectEqual(t, setCookie.Domain, "example.com")
+			ExpectEqual(t, setCookie.Path, "/")
+			ExpectEqual(t, setCookie.SameSite, http.SameSiteLaxMode)
+			ExpectEqual(t, setCookie.HttpOnly, true)
+			ExpectEqual(t, w.Code, http.StatusOK)
+		}
+	}
+}
diff --git a/internal/api/v1/auth/utils.go b/internal/api/v1/auth/utils.go
new file mode 100644
index 00000000..1d57de13
--- /dev/null
+++ b/internal/api/v1/auth/utils.go
@@ -0,0 +1,70 @@
+package auth
+
+import (
+	"net"
+	"net/http"
+	"time"
+
+	E "github.com/yusing/go-proxy/internal/error"
+	"github.com/yusing/go-proxy/internal/utils/strutils"
+)
+
+var (
+	ErrMissingToken   = E.New("missing token")
+	ErrInvalidToken   = E.New("invalid token")
+	ErrUserNotAllowed = E.New("user not allowed")
+)
+
+// cookieFQDN returns the fully qualified domain name of the request host
+// with subdomain stripped.
+//
+// If the request host does not have a subdomain,
+// an empty string is returned
+//
+//	"abc.example.com" -> "example.com"
+//	"example.com" -> ""
+func cookieFQDN(r *http.Request) string {
+	host, _, err := net.SplitHostPort(r.Host)
+	if err != nil {
+		host = r.Host
+	}
+	parts := strutils.SplitRune(host, '.')
+	if len(parts) < 2 {
+		return ""
+	}
+	parts[0] = ""
+	return strutils.JoinRune(parts, '.')
+}
+
+func setTokenCookie(w http.ResponseWriter, r *http.Request, name, value string, ttl time.Duration) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     name,
+		Value:    value,
+		MaxAge:   int(ttl.Seconds()),
+		Domain:   cookieFQDN(r),
+		HttpOnly: true,
+		Secure:   true,
+		SameSite: http.SameSiteLaxMode,
+		Path:     "/",
+	})
+}
+
+func clearTokenCookie(w http.ResponseWriter, r *http.Request, name string) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     name,
+		Value:    "",
+		MaxAge:   -1,
+		Domain:   cookieFQDN(r),
+		HttpOnly: true,
+		Secure:   true,
+		SameSite: http.SameSiteLaxMode,
+		Path:     "/",
+	})
+}
+
+func LogoutCallbackHandler(auth Provider) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		clearTokenCookie(w, r, auth.TokenCookieName())
+		auth.RedirectLoginPage(w, r)
+	}
+}
diff --git a/internal/api/v1/utils/logging.go b/internal/api/v1/utils/logging.go
index ac795b8c..194735f5 100644
--- a/internal/api/v1/utils/logging.go
+++ b/internal/api/v1/utils/logging.go
@@ -11,6 +11,7 @@ func reqLogger(r *http.Request, level zerolog.Level) *zerolog.Event {
 	return logging.WithLevel(level).
 		Str("module", "api").
 		Str("remote", r.RemoteAddr).
+		Str("host", r.Host).
 		Str("uri", r.Method+" "+r.RequestURI)
 }
 
diff --git a/internal/common/crypto.go b/internal/common/crypto.go
index 5afd0bfe..6214a572 100644
--- a/internal/common/crypto.go
+++ b/internal/common/crypto.go
@@ -1,18 +1,11 @@
 package common
 
 import (
-	"crypto/sha512"
 	"encoding/base64"
 
 	"github.com/rs/zerolog/log"
 )
 
-func HashPassword(pwd string) []byte {
-	h := sha512.New()
-	h.Write([]byte(pwd))
-	return h.Sum(nil)
-}
-
 func decodeJWTKey(key string) []byte {
 	if key == "" {
 		return nil
diff --git a/internal/common/env.go b/internal/common/env.go
index 0cc17553..4d13afe2 100644
--- a/internal/common/env.go
+++ b/internal/common/env.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/rs/zerolog/log"
+	"github.com/yusing/go-proxy/internal/utils/strutils"
 )
 
 var (
@@ -43,17 +44,19 @@ var (
 	MetricsHTTPURL = GetAddrEnv("PROMETHEUS_ADDR", "", "http")
 	PrometheusEnabled = MetricsHTTPURL != ""
 
-	APIJWTSecret    = decodeJWTKey(GetEnvString("API_JWT_SECRET", ""))
-	APIJWTTokenTTL  = GetDurationEnv("API_JWT_TOKEN_TTL", time.Hour)
-	APIUser         = GetEnvString("API_USER", "admin")
-	APIPasswordHash = HashPassword(GetEnvString("API_PASSWORD", "password"))
+	APIJWTSecret   = decodeJWTKey(GetEnvString("API_JWT_SECRET", ""))
+	APIJWTTokenTTL = GetDurationEnv("API_JWT_TOKEN_TTL", time.Hour)
+	APIUser        = GetEnvString("API_USER", "admin")
+	APIPassword    = GetEnvString("API_PASSWORD", "password")
 
 	// OIDC Configuration.
-	OIDCIssuerURL    = GetEnvString("OIDC_ISSUER_URL", "")
-	OIDCClientID     = GetEnvString("OIDC_CLIENT_ID", "")
-	OIDCClientSecret = GetEnvString("OIDC_CLIENT_SECRET", "")
-	OIDCRedirectURL  = GetEnvString("OIDC_REDIRECT_URL", "")
-	OIDCScopes       = GetEnvString("OIDC_SCOPES", "openid, profile, email")
+	OIDCIssuerURL     = GetEnvString("OIDC_ISSUER_URL", "")
+	OIDCClientID      = GetEnvString("OIDC_CLIENT_ID", "")
+	OIDCClientSecret  = GetEnvString("OIDC_CLIENT_SECRET", "")
+	OIDCRedirectURL   = GetEnvString("OIDC_REDIRECT_URL", "")
+	OIDCScopes        = GetEnvString("OIDC_SCOPES", "openid, profile, email")
+	OIDCAllowedUsers  = GetCommaSepEnv("OIDC_ALLOWED_USERS", "")
+	OIDCAllowedGroups = GetCommaSepEnv("OIDC_ALLOWED_GROUPS", "")
 )
 
 func GetEnv[T any](key string, defaultValue T, parser func(string) (T, error)) T {
@@ -105,3 +108,7 @@ func GetAddrEnv(key, defaultValue, scheme string) (addr, host, port, fullURL str
 func GetDurationEnv(key string, defaultValue time.Duration) time.Duration {
 	return GetEnv(key, defaultValue, time.ParseDuration)
 }
+
+func GetCommaSepEnv(key string, defaultValue string) []string {
+	return strutils.CommaSeperatedList(GetEnvString(key, defaultValue))
+}
diff --git a/internal/common/random.go b/internal/common/random.go
deleted file mode 100644
index ea4586f1..00000000
--- a/internal/common/random.go
+++ /dev/null
@@ -1,13 +0,0 @@
-package common
-
-import (
-	"crypto/rand"
-	"encoding/base64"
-)
-
-// GenerateRandomString generates a random string of specified length.
-func GenerateRandomString(length int) string {
-	b := make([]byte, length)
-	rand.Read(b)
-	return base64.URLEncoding.EncodeToString(b)[:length]
-}
diff --git a/internal/entrypoint/entrypoint.go b/internal/entrypoint/entrypoint.go
index a2f5c0a6..faed4898 100644
--- a/internal/entrypoint/entrypoint.go
+++ b/internal/entrypoint/entrypoint.go
@@ -89,7 +89,11 @@ func (ep *Entrypoint) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Then scraper / scanners will know the subdomain is invalid.
 	// With StatusNotFound, they won't know whether it's the path, or the subdomain that is invalid.
 	if served := middleware.ServeStaticErrorPageFile(w, r); !served {
-		logger.Err(err).Str("method", r.Method).Str("url", r.URL.String()).Msg("request")
+		logger.Err(err).
+			Str("method", r.Method).
+			Str("url", r.URL.String()).
+			Str("remote", r.RemoteAddr).
+			Msg("request")
 		errorPage, ok := errorpage.GetErrorPageByStatus(http.StatusNotFound)
 		if ok {
 			w.WriteHeader(http.StatusNotFound)
diff --git a/internal/net/http/middleware/middleware.go b/internal/net/http/middleware/middleware.go
index 78410d36..a2719722 100644
--- a/internal/net/http/middleware/middleware.go
+++ b/internal/net/http/middleware/middleware.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"reflect"
+	"sort"
 	"strings"
 
 	E "github.com/yusing/go-proxy/internal/error"
@@ -26,28 +27,50 @@ type (
 		name      string
 		construct ImplNewFunc
 		impl      any
+		// priority is only applied for ReverseProxy.
+		//
+		// Middleware compose follows the order of the slice
+		//
+		// Default is 10, 0 is the highest
+		priority int
 	}
+	ByPriority []*Middleware
 
 	RequestModifier interface {
 		before(w http.ResponseWriter, r *http.Request) (proceed bool)
 	}
-	ResponseModifier     interface{ modifyResponse(r *http.Response) error }
-	MiddlewareWithSetup  interface{ setup() }
-	MiddlewareFinalizer  interface{ finalize() }
+	ResponseModifier             interface{ modifyResponse(r *http.Response) error }
+	MiddlewareWithSetup          interface{ setup() }
+	MiddlewareFinalizer          interface{ finalize() }
+	MiddlewareFinalizerWithError interface {
+		finalize() error
+	}
 	MiddlewareWithTracer interface {
 		enableTrace()
 		getTracer() *Tracer
 	}
 )
 
+const DefaultPriority = 10
+
+func (m ByPriority) Len() int           { return len(m) }
+func (m ByPriority) Swap(i, j int)      { m[i], m[j] = m[j], m[i] }
+func (m ByPriority) Less(i, j int) bool { return m[i].priority < m[j].priority }
+
 func NewMiddleware[ImplType any]() *Middleware {
 	// type check
-	switch any(new(ImplType)).(type) {
+	t := any(new(ImplType))
+	switch t.(type) {
 	case RequestModifier:
 	case ResponseModifier:
 	default:
 		panic("must implement RequestModifier or ResponseModifier")
 	}
+	_, hasFinializer := t.(MiddlewareFinalizer)
+	_, hasFinializerWithError := t.(MiddlewareFinalizerWithError)
+	if hasFinializer && hasFinializerWithError {
+		panic("MiddlewareFinalizer and MiddlewareFinalizerWithError are mutually exclusive")
+	}
 	return &Middleware{
 		name:      strings.ToLower(reflect.TypeFor[ImplType]().Name()),
 		construct: func() any { return new(ImplType) },
@@ -84,13 +107,29 @@ func (m *Middleware) apply(optsRaw OptionsRaw) E.Error {
 	if len(optsRaw) == 0 {
 		return nil
 	}
+	priority, ok := optsRaw["priority"].(int)
+	if ok {
+		m.priority = priority
+		// remove priority for deserialization, restore later
+		delete(optsRaw, "priority")
+		defer func() {
+			optsRaw["priority"] = priority
+		}()
+	} else {
+		m.priority = DefaultPriority
+	}
 	return utils.Deserialize(optsRaw, m.impl)
 }
 
-func (m *Middleware) finalize() {
+func (m *Middleware) finalize() error {
 	if finalizer, ok := m.impl.(MiddlewareFinalizer); ok {
 		finalizer.finalize()
+		return nil
 	}
+	if finalizer, ok := m.impl.(MiddlewareFinalizerWithError); ok {
+		return finalizer.finalize()
+	}
+	return nil
 }
 
 func (m *Middleware) New(optsRaw OptionsRaw) (*Middleware, E.Error) {
@@ -105,7 +144,9 @@ func (m *Middleware) New(optsRaw OptionsRaw) (*Middleware, E.Error) {
 	if err := mid.apply(optsRaw); err != nil {
 		return nil, err
 	}
-	mid.finalize()
+	if err := mid.finalize(); err != nil {
+		return nil, E.From(err)
+	}
 	return mid, nil
 }
 
@@ -119,8 +160,9 @@ func (m *Middleware) String() string {
 
 func (m *Middleware) MarshalJSON() ([]byte, error) {
 	return json.MarshalIndent(map[string]any{
-		"name":    m.name,
-		"options": m.impl,
+		"name":     m.name,
+		"options":  m.impl,
+		"priority": m.priority,
 	}, "", "  ")
 }
 
@@ -193,6 +235,7 @@ func PatchReverseProxy(rp *ReverseProxy, middlewaresMap map[string]OptionsRaw) (
 }
 
 func patchReverseProxy(rp *ReverseProxy, middlewares []*Middleware) {
+	sort.Sort(ByPriority(middlewares))
 	middlewares = append([]*Middleware{newSetUpstreamHeaders(rp)}, middlewares...)
 
 	mid := NewMiddlewareChain(rp.TargetName, middlewares)
diff --git a/internal/net/http/middleware/middleware_test.go b/internal/net/http/middleware/middleware_test.go
new file mode 100644
index 00000000..5b6e5218
--- /dev/null
+++ b/internal/net/http/middleware/middleware_test.go
@@ -0,0 +1,37 @@
+package middleware
+
+import (
+	"net/http"
+	"strconv"
+	"strings"
+	"testing"
+
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+type testPriority struct {
+	Value int `json:"value"`
+}
+
+var test = NewMiddleware[testPriority]()
+
+func (t testPriority) before(w http.ResponseWriter, r *http.Request) bool {
+	w.Header().Add("Test-Value", strconv.Itoa(t.Value))
+	return true
+}
+
+func TestMiddlewarePriority(t *testing.T) {
+	priorities := []int{4, 7, 9, 0}
+	chain := make([]*Middleware, len(priorities))
+	for i, p := range priorities {
+		mid, err := test.New(OptionsRaw{
+			"priority": p,
+			"value":    i,
+		})
+		ExpectNoError(t, err)
+		chain[i] = mid
+	}
+	res, err := newMiddlewaresTest(chain, nil)
+	ExpectNoError(t, err)
+	ExpectEqual(t, strings.Join(res.ResponseHeaders["Test-Value"], ","), "3,0,1,2")
+}
diff --git a/internal/net/http/middleware/middlewares.go b/internal/net/http/middleware/middlewares.go
index cfea2c35..1785083c 100644
--- a/internal/net/http/middleware/middlewares.go
+++ b/internal/net/http/middleware/middlewares.go
@@ -14,6 +14,8 @@ import (
 var allMiddlewares = map[string]*Middleware{
 	"redirecthttp": RedirectHTTP,
 
+	"oidc": OIDC,
+
 	"request":        ModifyRequest,
 	"modifyrequest":  ModifyRequest,
 	"response":       ModifyResponse,
diff --git a/internal/net/http/middleware/oidc.go b/internal/net/http/middleware/oidc.go
new file mode 100644
index 00000000..8e1b3e67
--- /dev/null
+++ b/internal/net/http/middleware/oidc.go
@@ -0,0 +1,59 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/api/v1/auth"
+	E "github.com/yusing/go-proxy/internal/error"
+)
+
+type oidcMiddleware struct {
+	AllowedUsers  []string `json:"allowed_users"`
+	AllowedGroups []string `json:"allowed_groups"`
+
+	auth          auth.Provider
+	authMux       *http.ServeMux
+	logoutHandler http.HandlerFunc
+}
+
+var OIDC = NewMiddleware[oidcMiddleware]()
+
+func (amw *oidcMiddleware) finalize() error {
+	if !auth.IsOIDCEnabled() {
+		return E.New("OIDC not enabled but ODIC middleware is used")
+	}
+	authProvider, err := auth.NewOIDCProviderFromEnv()
+	if err != nil {
+		return err
+	}
+
+	authProvider.SetIsMiddleware(true)
+	if len(amw.AllowedUsers) > 0 {
+		authProvider.SetAllowedUsers(amw.AllowedUsers)
+	}
+	if len(amw.AllowedGroups) > 0 {
+		authProvider.SetAllowedGroups(amw.AllowedGroups)
+	}
+
+	amw.authMux = http.NewServeMux()
+	amw.authMux.HandleFunc(auth.OIDCMiddlewareCallbackPath, authProvider.LoginCallbackHandler)
+	amw.authMux.HandleFunc(auth.OIDCLogoutPath, func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+	})
+	amw.authMux.HandleFunc("/", authProvider.RedirectLoginPage)
+	amw.logoutHandler = auth.LogoutCallbackHandler(authProvider)
+	amw.auth = authProvider
+	return nil
+}
+
+func (amw *oidcMiddleware) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	if err := amw.auth.CheckToken(r); err != nil {
+		amw.authMux.ServeHTTP(w, r)
+		return false
+	}
+	if r.URL.Path == auth.OIDCLogoutPath {
+		amw.logoutHandler(w, r)
+		return false
+	}
+	return true
+}
diff --git a/internal/net/http/middleware/test_utils.go b/internal/net/http/middleware/test_utils.go
index dceeb39a..9c8ce3a4 100644
--- a/internal/net/http/middleware/test_utils.go
+++ b/internal/net/http/middleware/test_utils.go
@@ -127,6 +127,20 @@ func newMiddlewareTest(middleware *Middleware, args *testArgs) (*TestResult, E.E
 	}
 	args.setDefaults()
 
+	mid, setOptErr := middleware.New(args.middlewareOpt)
+	if setOptErr != nil {
+		return nil, setOptErr
+	}
+
+	return newMiddlewaresTest([]*Middleware{mid}, args)
+}
+
+func newMiddlewaresTest(middlewares []*Middleware, args *testArgs) (*TestResult, E.Error) {
+	if args == nil {
+		args = new(testArgs)
+	}
+	args.setDefaults()
+
 	req := httptest.NewRequest(args.reqMethod, args.reqURL.String(), args.bodyReader())
 	for k, v := range args.headers {
 		req.Header[k] = v
@@ -139,14 +153,8 @@ func newMiddlewareTest(middleware *Middleware, args *testArgs) (*TestResult, E.E
 		rr.parent = http.DefaultTransport
 	}
 
-	rp := reverseproxy.NewReverseProxy(middleware.name, args.upstreamURL, rr)
-
-	mid, setOptErr := middleware.New(args.middlewareOpt)
-	if setOptErr != nil {
-		return nil, setOptErr
-	}
-
-	patchReverseProxy(rp, []*Middleware{mid})
+	rp := reverseproxy.NewReverseProxy("test", args.upstreamURL, rr)
+	patchReverseProxy(rp, middlewares)
 	rp.ServeHTTP(w, req)
 
 	resp := w.Result()
diff --git a/internal/utils/slices.go b/internal/utils/slices.go
new file mode 100644
index 00000000..afe2914c
--- /dev/null
+++ b/internal/utils/slices.go
@@ -0,0 +1,20 @@
+package utils
+
+// Intersect returns a new slice containing the elements that are present in both input slices.
+// This provides a more efficient solution than using two nested loops.
+func Intersect[T comparable, Slice ~[]T](slice1 Slice, slice2 Slice) Slice {
+	var result Slice
+	seen := map[T]struct{}{}
+
+	for i := range slice1 {
+		seen[slice1[i]] = struct{}{}
+	}
+
+	for i := range slice2 {
+		if _, ok := seen[slice2[i]]; ok {
+			result = append(result, slice2[i])
+		}
+	}
+
+	return result
+}
diff --git a/internal/utils/slices_test.go b/internal/utils/slices_test.go
new file mode 100644
index 00000000..8d2a1f1a
--- /dev/null
+++ b/internal/utils/slices_test.go
@@ -0,0 +1,96 @@
+package utils
+
+import (
+	"slices"
+	"strings"
+	"testing"
+
+	utils "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+func TestIntersect(t *testing.T) {
+	t.Run("strings", func(t *testing.T) {
+		t.Run("no intersection", func(t *testing.T) {
+			var (
+				slice1 = []string{"a", "b", "c"}
+				slice2 = []string{"d", "e", "f"}
+				want   []string
+			)
+			result := Intersect(slice1, slice2)
+			slices.Sort(result)
+			slices.Sort(want)
+			utils.ExpectDeepEqual(t, result, want)
+		})
+		t.Run("intersection", func(t *testing.T) {
+			var (
+				slice1 = []string{"a", "b", "c"}
+				slice2 = []string{"b", "c", "d"}
+				want   = []string{"b", "c"}
+			)
+			result := Intersect(slice1, slice2)
+			slices.Sort(result)
+			slices.Sort(want)
+			utils.ExpectDeepEqual(t, result, want)
+		})
+	})
+	t.Run("ints", func(t *testing.T) {
+		t.Run("no intersection", func(t *testing.T) {
+			var (
+				slice1 = []int{1, 2, 3}
+				slice2 = []int{4, 5, 6}
+				want   []int
+			)
+			result := Intersect(slice1, slice2)
+			slices.Sort(result)
+			slices.Sort(want)
+			utils.ExpectDeepEqual(t, result, want)
+		})
+		t.Run("intersection", func(t *testing.T) {
+			var (
+				slice1 = []int{1, 2, 3}
+				slice2 = []int{2, 3, 4}
+				want   = []int{2, 3}
+			)
+			result := Intersect(slice1, slice2)
+			slices.Sort(result)
+			slices.Sort(want)
+			utils.ExpectDeepEqual(t, result, want)
+		})
+	})
+	t.Run("complex", func(t *testing.T) {
+		type T struct {
+			A string
+			B int
+		}
+		t.Run("no intersection", func(t *testing.T) {
+			var (
+				slice1 = []T{{"a", 1}, {"b", 2}, {"c", 3}}
+				slice2 = []T{{"d", 4}, {"e", 5}, {"f", 6}}
+				want   []T
+			)
+			result := Intersect(slice1, slice2)
+			slices.SortFunc(result, func(i T, j T) int {
+				return strings.Compare(i.A, j.A)
+			})
+			slices.SortFunc(want, func(i T, j T) int {
+				return strings.Compare(i.A, j.A)
+			})
+			utils.ExpectDeepEqual(t, result, want)
+		})
+		t.Run("intersection", func(t *testing.T) {
+			var (
+				slice1 = []T{{"a", 1}, {"b", 2}, {"c", 3}}
+				slice2 = []T{{"b", 2}, {"c", 3}, {"d", 4}}
+				want   = []T{{"b", 2}, {"c", 3}}
+			)
+			result := Intersect(slice1, slice2)
+			slices.SortFunc(result, func(i T, j T) int {
+				return strings.Compare(i.A, j.A)
+			})
+			slices.SortFunc(want, func(i T, j T) int {
+				return strings.Compare(i.A, j.A)
+			})
+			utils.ExpectDeepEqual(t, result, want)
+		})
+	})
+}
diff --git a/internal/utils/strutils/string.go b/internal/utils/strutils/string.go
index 4664c2b1..18f78c61 100644
--- a/internal/utils/strutils/string.go
+++ b/internal/utils/strutils/string.go
@@ -10,6 +10,9 @@ import (
 // CommaSeperatedList returns a list of strings split by commas,
 // then trim spaces from each element.
 func CommaSeperatedList(s string) []string {
+	if s == "" {
+		return []string{}
+	}
 	res := SplitComma(s)
 	for i, part := range res {
 		res[i] = strings.TrimSpace(part)
diff --git a/next-release.md b/next-release.md
index ae1989a5..e398b33e 100644
--- a/next-release.md
+++ b/next-release.md
@@ -73,6 +73,26 @@ GoDoxy v0.8.2 expected changes
   * Connection #0 to host localhost left intact
   ```
 
+- **Thanks [polds](https://github.com/polds)**
+  Support WebUI authentication via OIDC by setting these environment variables:
+  - `GODOXY_OIDC_ISSUER_URL` e.g.:
+    - Pocket ID: `https://pocker-id.yourdomain.com`
+    - Authentik: `https://authentik.yourdomain.com/application/o/<application_slug>/` **The ending slash is required**
+  - `GODOXY_OIDC_CLIENT_ID`
+  - `GODOXY_OIDC_CLIENT_SECRET`
+  - `GODOXY_OIDC_REDIRECT_URL`
+  - `GODOXY_OIDC_SCOPES` _(optional)_
+  - `GODOXY_OIDC_ALLOWED_USERS`
+
+- Use OpenID Connect to authenticate GoDoxy's WebUI and all your services (SSO)
+  ```yaml
+    # default
+  proxy.app.middlewares.oidc:
+
+  # override allowed users
+  proxy.app.middlewares.oidc.allowed_users: user1, user2
+  ```
+
 - Caddyfile like rules
 
   ```yaml