diff --git a/.gitignore b/.gitignore
index fb6b006..9db7613 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,8 @@ gpservice
 *_adaptor.cpp
 *_adaptor.h
 
+gpservice_interface.*
+
 # C++ objects and libs
 *.slo
 *.lo
diff --git a/GPClient/GPClient.pro b/GPClient/GPClient.pro
index 7d38d2c..0be925e 100644
--- a/GPClient/GPClient.pro
+++ b/GPClient/GPClient.pro
@@ -35,7 +35,8 @@ SOURCES += \
     portalconfigresponse.cpp \
     preloginresponse.cpp \
     samlloginwindow.cpp \
-    gpclient.cpp
+    gpclient.cpp \
+    settingsdialog.cpp
 
 HEADERS += \
     cdpcommand.h \
@@ -50,11 +51,13 @@ HEADERS += \
     portalconfigresponse.h \
     preloginresponse.h \
     samlloginwindow.h \
-    gpclient.h
+    gpclient.h \
+    settingsdialog.h
 
 FORMS += \
     gpclient.ui \
-    normalloginwindow.ui
+    normalloginwindow.ui \
+    settingsdialog.ui
 
 DBUS_INTERFACES += ../GPService/gpservice.xml
 
diff --git a/GPClient/gpclient.cpp b/GPClient/gpclient.cpp
index 4b2d079..89d36cd 100644
--- a/GPClient/gpclient.cpp
+++ b/GPClient/gpclient.cpp
@@ -3,6 +3,7 @@
 #include "ui_gpclient.h"
 #include "portalauthenticator.h"
 #include "gatewayauthenticator.h"
+#include "settingsdialog.h"
 
 #include <plog/Log.h>
 #include <QIcon>
@@ -12,12 +13,16 @@ using namespace gpclient::helper;
 GPClient::GPClient(QWidget *parent)
     : QMainWindow(parent)
     , ui(new Ui::GPClient)
+    , settingsDialog(new SettingsDialog(this))
 {
     ui->setupUi(this);
+
     setWindowTitle("GlobalProtect");
     setFixedSize(width(), height());
     gpclient::helper::moveCenter(this);
 
+    setupSettings();
+
     // Restore portal from the previous settings
     ui->portalInput->setText(settings::get("portal", "").toString());
 
@@ -36,6 +41,37 @@ GPClient::~GPClient()
 {
     delete ui;
     delete vpn;
+    delete settingsDialog;
+    delete settingsButton;
+}
+
+void GPClient::setupSettings()
+{
+    settingsButton = new QPushButton(this);
+    settingsButton->setIcon(QIcon(":/images/settings_icon.svg"));
+    settingsButton->setFixedSize(QSize(28, 28));
+
+    QRect rect = this->geometry();
+    settingsButton->setGeometry(
+                rect.width() - settingsButton->width() - 15,
+                15,
+                settingsButton->geometry().width(),
+                settingsButton->geometry().height()
+                );
+
+    connect(settingsButton, &QPushButton::clicked, this, &GPClient::onSettingsButtonClicked);
+    connect(settingsDialog, &QDialog::accepted, this, &GPClient::onSettingsAccepted);
+}
+
+void GPClient::onSettingsButtonClicked()
+{
+    settingsDialog->setExtraArgs(settings::get("extraArgs", "").toString());
+    settingsDialog->show();
+}
+
+void GPClient::onSettingsAccepted()
+{
+    settings::save("extraArgs", settingsDialog->extraArgs());
 }
 
 void GPClient::on_connectButton_clicked()
@@ -330,7 +366,7 @@ void GPClient::onGatewaySuccess(const QString &authCookie)
     PLOGI << "Gateway login succeeded, got the cookie " << authCookie;
 
     isQuickConnect = false;
-    vpn->connect(currentGateway().address(), portalConfig.username(), authCookie);
+    vpn->connect(currentGateway().address(), portalConfig.username(), authCookie, settings::get("extraArgs", "").toString());
     ui->statusLabel->setText("Connecting...");
     updateConnectionStatus(VpnStatus::pending);
 }
diff --git a/GPClient/gpclient.h b/GPClient/gpclient.h
index f3a15d0..a993a19 100644
--- a/GPClient/gpclient.h
+++ b/GPClient/gpclient.h
@@ -3,10 +3,12 @@
 
 #include "gpservice_interface.h"
 #include "portalconfigresponse.h"
+#include "settingsdialog.h"
 
 #include <QMainWindow>
 #include <QSystemTrayIcon>
 #include <QMenu>
+#include <QPushButton>
 
 QT_BEGIN_NAMESPACE
 namespace Ui { class GPClient; }
@@ -23,6 +25,9 @@ public:
     void activate();
 
 private slots:
+    void onSettingsButtonClicked();
+    void onSettingsAccepted();
+
     void on_connectButton_clicked();
     void on_portalInput_returnPressed();
     void on_portalInput_editingFinished();
@@ -62,10 +67,15 @@ private:
     QAction *clearAction;
     QAction *quitAction;
 
+    SettingsDialog *settingsDialog;
+    QPushButton *settingsButton;
+
     bool isQuickConnect { false };
     bool isSwitchingGateway { false };
     PortalConfigResponse portalConfig;
 
+    void setupSettings();
+
     void initSystemTrayIcon();
     void initVpnStatus();
     void populateGatewayMenu();
diff --git a/GPClient/resources.qrc b/GPClient/resources.qrc
index 88130b8..f6ee3f6 100644
--- a/GPClient/resources.qrc
+++ b/GPClient/resources.qrc
@@ -6,5 +6,6 @@
         <file>not_connected.png</file>
         <file>radio_unselected.png</file>
         <file>radio_selected.png</file>
+        <file>settings_icon.svg</file>
     </qresource>
 </RCC>
diff --git a/GPClient/settings_icon.svg b/GPClient/settings_icon.svg
new file mode 100644
index 0000000..7a6140a
--- /dev/null
+++ b/GPClient/settings_icon.svg
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Generator: Adobe Illustrator 23.0.3, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+<svg version="1.1" id="Icons" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 viewBox="0 0 32 32" style="enable-background:new 0 0 32 32;" xml:space="preserve">
+<g>
+	<path d="M16.5,19.9C16.5,19.9,16.5,19.9,16.5,19.9l3.1-3.1c0,0,0,0,0,0l2.3-2.3c2.2,0.6,4.5,0,6.2-1.6c1.8-1.8,2.3-4.4,1.4-6.8
+		c-0.1-0.3-0.4-0.5-0.7-0.6c-0.3-0.1-0.7,0-0.9,0.3L25.6,8l-1.3-0.3L24,6.4l2.2-2.2c0.2-0.2,0.3-0.6,0.3-0.9
+		c-0.1-0.3-0.3-0.6-0.6-0.7c-2.3-0.9-5-0.4-6.8,1.4c-1.6,1.6-2.2,4-1.6,6.2l-1.6,1.6l-2.6-2.6L11,5.3c-0.1-0.1-0.2-0.3-0.3-0.3
+		L6.8,2.7C6.4,2.4,5.9,2.5,5.5,2.8L2.5,5.9C2.1,6.2,2.1,6.7,2.3,7.1L4.6,11c0.1,0.1,0.2,0.3,0.3,0.3l3.7,2.2l2.6,2.6l-1.2,1.2
+		c-2.2-0.6-4.5,0-6.2,1.6c-1.8,1.8-2.3,4.4-1.4,6.8c0.1,0.3,0.4,0.5,0.7,0.6c0.3,0.1,0.7,0,0.9-0.3L6.4,24l1.3,0.3L8,25.6l-2.2,2.2
+		c-0.2,0.2-0.3,0.6-0.3,0.9c0.1,0.3,0.3,0.6,0.6,0.7c0.8,0.3,1.5,0.4,2.3,0.4c1.6,0,3.3-0.6,4.5-1.9c1.6-1.6,2.2-4,1.6-6.2
+		L16.5,19.9z"/>
+	<path d="M22.5,16.8l-6,6l6.1,6.1c0.8,0.8,1.9,1.3,3,1.3s2.2-0.4,3-1.3c0.8-0.8,1.3-1.9,1.3-3c0-1.1-0.4-2.2-1.3-3L22.5,16.8z"/>
+</g>
+</svg>
diff --git a/GPClient/settingsdialog.cpp b/GPClient/settingsdialog.cpp
new file mode 100644
index 0000000..b36a729
--- /dev/null
+++ b/GPClient/settingsdialog.cpp
@@ -0,0 +1,26 @@
+#include "settingsdialog.h"
+#include "ui_settingsdialog.h"
+
+SettingsDialog::SettingsDialog(QWidget *parent) :
+    QDialog(parent),
+    ui(new Ui::SettingsDialog)
+{
+    ui->setupUi(this);
+
+    ui->extraArgsInput->setPlaceholderText("e.g. --name=value");
+}
+
+SettingsDialog::~SettingsDialog()
+{
+    delete ui;
+}
+
+void SettingsDialog::setExtraArgs(QString args)
+{
+    ui->extraArgsInput->setPlainText(args);
+}
+
+QString SettingsDialog::extraArgs()
+{
+    return ui->extraArgsInput->toPlainText().trimmed();
+}
diff --git a/GPClient/settingsdialog.h b/GPClient/settingsdialog.h
new file mode 100644
index 0000000..9208a9c
--- /dev/null
+++ b/GPClient/settingsdialog.h
@@ -0,0 +1,25 @@
+#ifndef SETTINGSDIALOG_H
+#define SETTINGSDIALOG_H
+
+#include <QDialog>
+
+namespace Ui {
+class SettingsDialog;
+}
+
+class SettingsDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit SettingsDialog(QWidget *parent = nullptr);
+    ~SettingsDialog();
+
+    void setExtraArgs(QString);
+    QString extraArgs();
+
+private:
+    Ui::SettingsDialog *ui;
+};
+
+#endif // SETTINGSDIALOG_H
diff --git a/GPClient/settingsdialog.ui b/GPClient/settingsdialog.ui
new file mode 100644
index 0000000..b601d9e
--- /dev/null
+++ b/GPClient/settingsdialog.ui
@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>SettingsDialog</class>
+ <widget class="QDialog" name="SettingsDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>470</width>
+    <height>183</height>
+   </rect>
+  </property>
+  <property name="sizePolicy">
+   <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
+    <horstretch>0</horstretch>
+    <verstretch>0</verstretch>
+   </sizepolicy>
+  </property>
+  <property name="windowTitle">
+   <string>Settings</string>
+  </property>
+  <property name="windowIcon">
+   <iconset resource="resources.qrc">
+    <normaloff>:/images/connected.png</normaloff>:/images/connected.png</iconset>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <widget class="QLabel" name="label">
+     <property name="text">
+      <string>Custom Parameters:</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QPlainTextEdit" name="extraArgsInput"/>
+   </item>
+   <item>
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources>
+  <include location="resources.qrc"/>
+ </resources>
+ <connections>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>accepted()</signal>
+   <receiver>SettingsDialog</receiver>
+   <slot>accept()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>248</x>
+     <y>254</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>157</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>rejected()</signal>
+   <receiver>SettingsDialog</receiver>
+   <slot>reject()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>316</x>
+     <y>260</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>286</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+ </connections>
+</ui>
diff --git a/GPService/gpservice.cpp b/GPService/gpservice.cpp
index 5426d59..b3f72d6 100644
--- a/GPService/gpservice.cpp
+++ b/GPService/gpservice.cpp
@@ -49,7 +49,7 @@ void GPService::quit()
     }
 }
 
-void GPService::connect(QString server, QString username, QString passwd)
+void GPService::connect(QString server, QString username, QString passwd, QString extraArgs)
 {
     if (vpnStatus != GPService::VpnNotConnected) {
         log("VPN status is: " + QVariant::fromValue(vpnStatus).toString());
@@ -65,10 +65,13 @@ void GPService::connect(QString server, QString username, QString passwd)
     QStringList args;
     args << QCoreApplication::arguments().mid(1)
      << "--protocol=gp"
+     << QProcess::splitCommand(extraArgs)
      << "-u" << username
      << "-C" << passwd
      << server;
 
+    log("Start process with arugments: " + args.join(" "));
+
     openconnect->start(bin, args);
 }
 
diff --git a/GPService/gpservice.h b/GPService/gpservice.h
index 0d1e536..ce753a8 100644
--- a/GPService/gpservice.h
+++ b/GPService/gpservice.h
@@ -34,7 +34,7 @@ signals:
     void logAvailable(QString log);
 
 public slots:
-    void connect(QString server, QString username, QString passwd);
+    void connect(QString server, QString username, QString passwd, QString extraArgs);
     void disconnect();
     int status();
     void quit();
diff --git a/GPService/gpservice.xml b/GPService/gpservice.xml
index de8b11d..202573d 100644
--- a/GPService/gpservice.xml
+++ b/GPService/gpservice.xml
@@ -12,6 +12,7 @@
       <arg name="server" type="s" direction="in"/>
       <arg name="username" type="s" direction="in"/>
       <arg name="passwd" type="s" direction="in"/>
+      <arg name="extraArgs" type="s" direction="in"/>
     </method>
     <method name="disconnect">
     </method>
diff --git a/README.md b/README.md
index 5d4985b..1e25bd8 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,13 @@ A GlobalProtect VPN client (GUI) for Linux based on Openconnect and built with Q
 - Supports automatically selecting the preferred gateway from the multiple gateways.
 - Supports switching gateway from the system tray menu manually.
 
+## Passing the Custom Parameters to `OpenConnect` CLI
+
+Custom parameters can be appended to the `OpenConnect` CLI with the following settings.
+<p align="center">
+ <img src="https://user-images.githubusercontent.com/3297602/129464304-94eb8a2b-1c4a-47e1-b931-4422fff6eb81.png" />
+<p>
+  
 ## Prerequisites
 
 - Openconnect v8.x