diff --git a/apps/gpauth/Cargo.toml b/apps/gpauth/Cargo.toml
index 5dd859f8..9a8acd00 100644
--- a/apps/gpauth/Cargo.toml
+++ b/apps/gpauth/Cargo.toml
@@ -1,5 +1,6 @@
 [package]
 name = "gpauth"
+authors.workspace = true
 version.workspace = true
 edition.workspace = true
 license.workspace = true
diff --git a/apps/gpauth/src/cli.rs b/apps/gpauth/src/cli.rs
index d59a775f..bf94362b 100644
--- a/apps/gpauth/src/cli.rs
+++ b/apps/gpauth/src/cli.rs
@@ -1,3 +1,5 @@
+use std::{env::temp_dir, fs, os::unix::fs::PermissionsExt};
+
 use clap::Parser;
 use gpapi::{
   auth::{SamlAuthData, SamlAuthResult},
@@ -11,36 +13,68 @@ use log::{info, LevelFilter};
 use serde_json::json;
 use tauri::{App, AppHandle, RunEvent};
 use tempfile::NamedTempFile;
+use tokio::{io::AsyncReadExt, net::TcpListener};
 
 use crate::auth_window::{portal_prelogin, AuthWindow};
 
 const VERSION: &str = concat!(env!("CARGO_PKG_VERSION"), " (", compile_time::date_str!(), ")");
 
 #[derive(Parser, Clone)]
-#[command(version = VERSION)]
+#[command(
+  version = VERSION,
+  author,
+  about = "The authentication component for the GlobalProtect VPN client, supports the SSO authentication method.",
+  help_template = "\
+{before-help}{name} {version}
+{author}
+
+{about}
+
+{usage-heading} {usage}
+
+{all-args}{after-help}
+
+See 'gpauth -h' for more information.
+"
+)]
 struct Cli {
+  #[arg(help = "The portal server to authenticate")]
   server: String,
-  #[arg(long)]
+
+  #[arg(long, help = "Treating the server as a gateway")]
   gateway: bool,
-  #[arg(long)]
+
+  #[arg(long, help = "The SAML authentication request")]
   saml_request: Option<String>,
-  #[arg(long, default_value = GP_USER_AGENT)]
+
+  #[arg(long, default_value = GP_USER_AGENT, help = "The user agent to use")]
   user_agent: String,
+
   #[arg(long, default_value = "Linux")]
   os: Os,
+
   #[arg(long)]
   os_version: Option<String>,
-  #[arg(long)]
+
+  #[arg(long, help = "The HiDPI mode, useful for high-resolution screens")]
   hidpi: bool,
-  #[arg(long)]
+
+  #[arg(long, help = "Get around the OpenSSL `unsafe legacy renegotiation` error")]
   fix_openssl: bool,
-  #[arg(long)]
+
+  #[arg(long, help = "Ignore TLS errors")]
   ignore_tls_errors: bool,
-  #[arg(long)]
+
+  #[arg(long, help = "Clean the cache of the embedded browser")]
   clean: bool,
-  #[arg(long)]
+
+  #[arg(long, help = "Use the default browser for authentication")]
   default_browser: bool,
-  #[arg(long)]
+
+  #[arg(
+    long,
+    help = "The browser to use for authentication, e.g., `default`, `firefox`, `chrome`, `chromium`, or the path to the browser executable"
+  )]
   browser: Option<String>,
 }
 
@@ -74,6 +108,15 @@ impl Cli {
 
       info!("Please continue the authentication process in the default browser");
 
+      let auth_result = match wait_auth_data().await {
+        Ok(auth_data) => SamlAuthResult::Success(auth_data),
+        Err(err) => SamlAuthResult::Failure(format!("{}", err)),
+      };
+
+      info!("Authentication completed");
+
+      println!("{}", json!(auth_result));
+
       return Ok(());
     }
 
@@ -181,3 +224,35 @@ pub async fn run() {
     std::process::exit(1);
   }
 }
+
+async fn wait_auth_data() -> anyhow::Result<SamlAuthData> {
+  // Start a local server to receive the browser authentication data
+  let listener = TcpListener::bind("127.0.0.1:0").await?;
+  let port = listener.local_addr()?.port();
+  let port_file = temp_dir().join("gpcallback.port");
+
+  // Write the port to a file
+  fs::write(&port_file, port.to_string())?;
+  fs::set_permissions(&port_file, fs::Permissions::from_mode(0o600))?;
+
+  // Remove the previous log file
+  let callback_log = temp_dir().join("gpcallback.log");
+  let _ = fs::remove_file(&callback_log);
+
+  info!("Listening authentication data on port {}", port);
+  info!(
+    "If it hangs, please check the logs at `{}` for more information",
+    callback_log.display()
+  );
+  let (mut socket, _) = listener.accept().await?;
+
+  info!("Received the browser authentication data from the socket");
+  let mut data = String::new();
+  socket.read_to_string(&mut data).await?;
+
+  // Remove the port file
+  fs::remove_file(&port_file)?;
+
+  let auth_data = SamlAuthData::from_gpcallback(&data)?;
+  Ok(auth_data)
+}
diff --git a/apps/gpclient/src/cli.rs b/apps/gpclient/src/cli.rs
index 24a399d7..8c377d79 100644
--- a/apps/gpclient/src/cli.rs
+++ b/apps/gpclient/src/cli.rs
@@ -1,3 +1,5 @@
+use std::{env::temp_dir, fs::File};
+
 use clap::{Parser, Subcommand};
 use gpapi::utils::openssl;
 use log::{info, LevelFilter};
@@ -85,14 +87,29 @@ impl Cli {
   }
 }
 
-fn init_logger() {
-  env_logger::builder().filter_level(LevelFilter::Info).init();
+fn init_logger(command: &CliCommand) {
+  let mut builder = env_logger::builder();
+  builder.filter_level(LevelFilter::Info);
+
+  // Output the log messages to a file if the command is the auth callback
+  if let CliCommand::LaunchGui(args) = command {
+    let auth_data = args.auth_data.as_deref().unwrap_or_default();
+    if !auth_data.is_empty() {
+      if let Ok(log_file) = File::create(temp_dir().join("gpcallback.log")) {
+        let target = Box::new(log_file);
+        builder.target(env_logger::Target::Pipe(target));
+      }
+    }
+  }
+
+  builder.init();
 }
 
 pub(crate) async fn run() {
   let cli = Cli::parse();
 
-  init_logger();
+  init_logger(&cli.command);
+
   info!("gpclient started: {}", VERSION);
 
   if let Err(err) = cli.run().await {
diff --git a/apps/gpclient/src/connect.rs b/apps/gpclient/src/connect.rs
index d0536a23..15c24707 100644
--- a/apps/gpclient/src/connect.rs
+++ b/apps/gpclient/src/connect.rs
@@ -1,8 +1,10 @@
 use std::{cell::RefCell, fs, sync::Arc};
 
+use anyhow::bail;
 use clap::Args;
 use common::vpn_utils::find_csd_wrapper;
 use gpapi::{
+  auth::SamlAuthResult,
   clap::args::Os,
   credential::{Credential, PasswordCredential},
   error::PortalError,
@@ -19,9 +21,8 @@ use gpapi::{
 use inquire::{Password, PasswordDisplayMode, Select, Text};
 use log::info;
 use openconnect::Vpn;
-use tokio::{io::AsyncReadExt, net::TcpListener};
 
-use crate::{cli::SharedArgs, GP_CLIENT_LOCK_FILE, GP_CLIENT_PORT_FILE};
+use crate::{cli::SharedArgs, GP_CLIENT_LOCK_FILE};
 
 #[derive(Args)]
 pub(crate) struct ConnectArgs {
@@ -37,6 +38,9 @@ pub(crate) struct ConnectArgs {
   #[arg(long, help = "Read the password from standard input")]
   passwd_on_stdin: bool,
 
+  #[arg(long, help = "Read the cookie from standard input")]
+  cookie_on_stdin: bool,
+
   #[arg(long, short, help = "The VPNC script to use")]
   script: Option<String>,
 
@@ -89,7 +93,7 @@ pub(crate) struct ConnectArgs {
   #[arg(long, help = "Disable DTLS and ESP")]
   no_dtls: bool,
 
-  #[arg(long, help = "The HiDPI mode, useful for high resolution screens")]
+  #[arg(long, help = "The HiDPI mode, useful for high-resolution screens")]
   hidpi: bool,
 
   #[arg(long, help = "Do not reuse the remembered authentication cookie")]
@@ -100,7 +104,7 @@ pub(crate) struct ConnectArgs {
 
   #[arg(
     long,
-    help = "Use the specified browser to authenticate, e.g., firefox, chromium, chrome, or the path to the browser"
+    help = "Use the specified browser to authenticate, e.g., `default`, `firefox`, `chrome`, `chromium`, or the path to the browser executable"
   )]
   browser: Option<String>,
 }
@@ -147,6 +151,10 @@ impl<'a> ConnectHandler<'a> {
   }
 
   pub(crate) async fn handle(&self) -> anyhow::Result<()> {
+    if self.args.default_browser && self.args.browser.is_some() {
+      bail!("Cannot use `--default-browser` and `--browser` options at the same time");
+    }
+
     self.latest_key_password.replace(self.args.key_password.clone());
 
     loop {
@@ -327,6 +335,10 @@ impl<'a> ConnectHandler<'a> {
   }
 
   async fn obtain_credential(&self, prelogin: &Prelogin, server: &str) -> anyhow::Result<Credential> {
+    if self.args.cookie_on_stdin {
+      return read_cookie_from_stdin();
+    }
+
     let is_gateway = prelogin.is_gateway();
 
     match prelogin {
@@ -353,18 +365,9 @@ impl<'a> ConnectHandler<'a> {
           .launch()
           .await?;
 
-        if let Some(cred) = cred {
-          return Ok(cred);
-        }
-
-        if !use_default_browser {
-          // This should never happen
-          unreachable!("SAML authentication failed without using the default browser");
-        }
-
-        info!("Waiting for the browser authentication to complete...");
-        wait_credentials().await
+        Ok(cred)
       }
+
       Prelogin::Standard(prelogin) => {
         let prefix = if is_gateway { "Gateway" } else { "Portal" };
         println!("{} ({}: {})", prelogin.auth_message(), prefix, server);
@@ -394,25 +397,17 @@ impl<'a> ConnectHandler<'a> {
   }
 }
 
-async fn wait_credentials() -> anyhow::Result<Credential> {
-  // Start a local server to receive the browser authentication data
-  let listener = TcpListener::bind("127.0.0.1:0").await?;
-  let port = listener.local_addr()?.port();
-
-  // Write the port to a file
-  fs::write(GP_CLIENT_PORT_FILE, port.to_string())?;
-
-  info!("Listening authentication data on port {}", port);
-  let (mut socket, _) = listener.accept().await?;
+fn read_cookie_from_stdin() -> anyhow::Result<Credential> {
+  info!("Reading cookie from standard input");
 
-  info!("Received the browser authentication data from the socket");
-  let mut data = String::new();
-  socket.read_to_string(&mut data).await?;
+  let mut cookie = String::new();
+  std::io::stdin().read_line(&mut cookie)?;
 
-  // Remove the port file
-  fs::remove_file(GP_CLIENT_PORT_FILE)?;
+  let Ok(auth_result) = serde_json::from_str::<SamlAuthResult>(cookie.trim_end()) else {
+    bail!("Failed to parse auth data")
+  };
 
-  Credential::from_gpcallback(&data)
+  Credential::try_from(auth_result)
 }
 
 fn write_pid_file() {
diff --git a/apps/gpclient/src/launch_gui.rs b/apps/gpclient/src/launch_gui.rs
index 4104d351..8cb6069d 100644
--- a/apps/gpclient/src/launch_gui.rs
+++ b/apps/gpclient/src/launch_gui.rs
@@ -9,15 +9,13 @@ use gpapi::{
 use log::info;
 use tokio::io::AsyncWriteExt;
 
-use crate::GP_CLIENT_PORT_FILE;
-
 #[derive(Args)]
 pub(crate) struct LaunchGuiArgs {
   #[arg(
     required = false,
     help = "The authentication data, used for the default browser authentication"
   )]
-  auth_data: Option<String>,
+  pub auth_data: Option<String>,
   #[arg(long, help = "Launch the GUI minimized")]
   minimized: bool,
 }
@@ -40,6 +38,7 @@ impl<'a> LaunchGuiHandler<'a> {
 
     let auth_data = self.args.auth_data.as_deref().unwrap_or_default();
     if !auth_data.is_empty() {
+      info!("Received auth callback data");
       // Process the authentication data, its format is `globalprotectcallback:<data>`
       return feed_auth_data(auth_data).await;
     }
@@ -81,16 +80,26 @@ impl<'a> LaunchGuiHandler<'a> {
 }
 
 async fn feed_auth_data(auth_data: &str) -> anyhow::Result<()> {
-  let _ = tokio::join!(feed_auth_data_gui(auth_data), feed_auth_data_cli(auth_data));
+  let (res_gui, res_cli) = tokio::join!(feed_auth_data_gui(auth_data), feed_auth_data_cli(auth_data));
+  if let Err(err) = res_gui {
+    info!("Failed to feed auth data to the GUI: {}", err);
+  }
+
+  if let Err(err) = res_cli {
+    info!("Failed to feed auth data to the CLI: {}", err);
+  }
 
   // Cleanup the temporary file
   let html_file = temp_dir().join("gpauth.html");
-  let _ = std::fs::remove_file(html_file);
+  if let Err(err) = std::fs::remove_file(&html_file) {
+    info!("Failed to remove {}: {}", html_file.display(), err);
+  }
 
   Ok(())
 }
 
 async fn feed_auth_data_gui(auth_data: &str) -> anyhow::Result<()> {
+  info!("Feeding auth data to the GUI");
   let service_endpoint = http_endpoint().await?;
 
   reqwest::Client::default()
@@ -104,7 +113,10 @@ async fn feed_auth_data_gui(auth_data: &str) -> anyhow::Result<()> {
 }
 
 async fn feed_auth_data_cli(auth_data: &str) -> anyhow::Result<()> {
-  let port = tokio::fs::read_to_string(GP_CLIENT_PORT_FILE).await?;
+  info!("Feeding auth data to the CLI");
+
+  let port_file = temp_dir().join("gpcallback.port");
+  let port = tokio::fs::read_to_string(port_file).await?;
   let mut stream = tokio::net::TcpStream::connect(format!("127.0.0.1:{}", port.trim())).await?;
 
   stream.write_all(auth_data.as_bytes()).await?;
@@ -124,7 +136,7 @@ async fn try_active_gui() -> anyhow::Result<()> {
   Ok(())
 }
 
-pub fn get_log_file() -> anyhow::Result<PathBuf> {
+fn get_log_file() -> anyhow::Result<PathBuf> {
   let dirs = ProjectDirs::from("com.yuezk", "GlobalProtect-openconnect", "gpclient")
     .ok_or_else(|| anyhow::anyhow!("Failed to get project dirs"))?;
 
diff --git a/apps/gpclient/src/main.rs b/apps/gpclient/src/main.rs
index 0c6e7634..41343ed2 100644
--- a/apps/gpclient/src/main.rs
+++ b/apps/gpclient/src/main.rs
@@ -4,7 +4,6 @@ mod disconnect;
 mod launch_gui;
 
 pub(crate) const GP_CLIENT_LOCK_FILE: &str = "/var/run/gpclient.lock";
-pub(crate) const GP_CLIENT_PORT_FILE: &str = "/var/run/gpclient.port";
 
 #[tokio::main]
 async fn main() {
diff --git a/crates/gpapi/src/auth.rs b/crates/gpapi/src/auth.rs
index 245c7d01..86ddcd4f 100644
--- a/crates/gpapi/src/auth.rs
+++ b/crates/gpapi/src/auth.rs
@@ -85,7 +85,6 @@ impl SamlAuthData {
       return Ok(auth_data);
     }
 
-    info!("Parsing SAML auth data...");
     let auth_data = decode_to_string(auth_data).map_err(|e| {
       warn!("Failed to decode SAML auth data: {}", e);
       AuthDataParseError::Invalid
diff --git a/crates/gpapi/src/credential.rs b/crates/gpapi/src/credential.rs
index 93a06df2..259385d3 100644
--- a/crates/gpapi/src/credential.rs
+++ b/crates/gpapi/src/credential.rs
@@ -1,9 +1,10 @@
 use std::collections::HashMap;
 
+use anyhow::bail;
 use serde::{Deserialize, Serialize};
 use specta::Type;
 
-use crate::auth::SamlAuthData;
+use crate::auth::{SamlAuthData, SamlAuthResult};
 
 #[derive(Debug, Serialize, Deserialize, Type, Clone)]
 #[serde(rename_all = "camelCase")]
@@ -230,6 +231,17 @@ impl From<SamlAuthData> for Credential {
   }
 }
 
+impl TryFrom<SamlAuthResult> for Credential {
+  type Error = anyhow::Error;
+
+  fn try_from(value: SamlAuthResult) -> anyhow::Result<Self> {
+    match value {
+      SamlAuthResult::Success(auth_data) => Ok(Self::from(auth_data)),
+      SamlAuthResult::Failure(err) => bail!(err),
+    }
+  }
+}
+
 impl From<PasswordCredential> for Credential {
   fn from(value: PasswordCredential) -> Self {
     Self::Password(value)
diff --git a/crates/gpapi/src/gateway/login.rs b/crates/gpapi/src/gateway/login.rs
index 8c4cc684..0188e22b 100644
--- a/crates/gpapi/src/gateway/login.rs
+++ b/crates/gpapi/src/gateway/login.rs
@@ -29,7 +29,7 @@ pub async fn gateway_login(gateway: &str, cred: &Credential, gp_params: &GpParam
   params.extend(extra_params);
   params.insert("server", &gateway);
 
-  info!("Gateway login, user_agent: {}", gp_params.user_agent());
+  info!("Perform gateway login, user_agent: {}", gp_params.user_agent());
 
   let res = client
     .post(&login_url)
diff --git a/crates/gpapi/src/portal/config.rs b/crates/gpapi/src/portal/config.rs
index 709fd56f..f775d572 100644
--- a/crates/gpapi/src/portal/config.rs
+++ b/crates/gpapi/src/portal/config.rs
@@ -109,7 +109,7 @@ pub async fn retrieve_config(portal: &str, cred: &Credential, gp_params: &GpPara
   params.insert("server", &server);
   params.insert("host", &server);
 
-  info!("Portal config, user_agent: {}", gp_params.user_agent());
+  info!("Retrieve the portal config, user_agent: {}", gp_params.user_agent());
 
   let res = client
     .post(&url)
diff --git a/crates/gpapi/src/portal/prelogin.rs b/crates/gpapi/src/portal/prelogin.rs
index 3952a73e..4c10d2ab 100644
--- a/crates/gpapi/src/portal/prelogin.rs
+++ b/crates/gpapi/src/portal/prelogin.rs
@@ -116,6 +116,8 @@ pub async fn prelogin(portal: &str, gp_params: &GpParams) -> anyhow::Result<Prel
 
   let client = Client::try_from(gp_params)?;
 
+  info!("Perform prelogin, user_agent: {}", gp_params.user_agent());
+
   let res = client
     .post(&prelogin_url)
     .form(&params)
diff --git a/crates/gpapi/src/process/auth_launcher.rs b/crates/gpapi/src/process/auth_launcher.rs
index 4eae32e5..15edcef8 100644
--- a/crates/gpapi/src/process/auth_launcher.rs
+++ b/crates/gpapi/src/process/auth_launcher.rs
@@ -96,7 +96,7 @@ impl<'a> SamlAuthLauncher<'a> {
   }
 
   /// Launch the authenticator binary as the current user or SUDO_USER if available.
-  pub async fn launch(self) -> anyhow::Result<Option<Credential>> {
+  pub async fn launch(self) -> anyhow::Result<Credential> {
     let mut auth_cmd = Command::new(GP_AUTH_BINARY);
     auth_cmd.arg(self.server);
 
@@ -152,17 +152,10 @@ impl<'a> SamlAuthLauncher<'a> {
       .wait_with_output()
       .await?;
 
-    if self.default_browser {
-      return Ok(None);
-    }
-
     let Ok(auth_result) = serde_json::from_slice::<SamlAuthResult>(&output.stdout) else {
       bail!("Failed to parse auth data")
     };
 
-    match auth_result {
-      SamlAuthResult::Success(auth_data) => Ok(Some(Credential::from(auth_data))),
-      SamlAuthResult::Failure(msg) => bail!(msg),
-    }
+    Credential::try_from(auth_result)
   }
 }
diff --git a/crates/gpapi/src/process/browser_authenticator.rs b/crates/gpapi/src/process/browser_authenticator.rs
index ffdf0d87..9da35d06 100644
--- a/crates/gpapi/src/process/browser_authenticator.rs
+++ b/crates/gpapi/src/process/browser_authenticator.rs
@@ -19,7 +19,7 @@ impl BrowserAuthenticator<'_> {
   pub fn new_with_browser<'a>(auth_request: &'a str, browser: &'a str) -> BrowserAuthenticator<'a> {
     BrowserAuthenticator {
       auth_request,
-      browser: Some(browser),
+      browser: if browser == "default" { None } else { Some(browser) },
     }
   }