diff --git a/src/main.rs b/src/main.rs
index 7639793..3cc55b1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,12 +1,30 @@
+use std::process::exit;
+use std::thread::sleep;
+use std::time::Duration;
 use crate::log::LogLevel;
+use crate::log::log;
+use crate::network::network_card::is_network_card_up;
 
 mod log;
+mod network;
 
 fn main() {
-    log::log("main", "========== PROGRAMM START ==========", LogLevel::Info);
+    log("main", "========== PROGRAMM START ==========", LogLevel::Info);
 
-    log::log("main", "Hello, world!", LogLevel::Error);
-    log::log("main", "Hello, world!", LogLevel::Warn);
-    log::log("main", "Hello, world!", LogLevel::Info);
-    log::log("main", "Hello, world!", LogLevel::Debug);
+    let mut count = 0;
+    loop {
+        if count >= 10 {
+            log("main", "Couldn't find active network card, exiting.", LogLevel::Error);
+            exit(1);
+        }
+        if is_network_card_up() {
+            break;
+        }
+
+        log("main", "No active network card found, waiting 10 seconds.", LogLevel::Warn);
+        count = count+1;
+        sleep(Duration::from_secs(10));
+    }
+    
+    log("main", "========== PROGRAMM END ==========", LogLevel::Info);
 }
diff --git a/src/network/mod.rs b/src/network/mod.rs
new file mode 100644
index 0000000..5decd83
--- /dev/null
+++ b/src/network/mod.rs
@@ -0,0 +1 @@
+pub mod network_card;
\ No newline at end of file
diff --git a/src/network/network_card.rs b/src/network/network_card.rs
new file mode 100644
index 0000000..10b3910
--- /dev/null
+++ b/src/network/network_card.rs
@@ -0,0 +1,136 @@
+use crate::log;
+use crate::log::LogLevel;
+use std::process::Command;
+
+/// Prüft, ob mindestens eine verfügbare Netzwerkschnittstelle (LAN/WLAN etc.) aktiv ist
+/// und nicht nur die Loopback-Schnittstelle.
+///
+/// Rückgabe:
+/// - true: Mindestens eine NIC ist aktiv
+/// - false: Keine aktive NIC gefunden oder Fehler beim Prüfen
+pub fn is_network_card_up() -> bool {
+    #[cfg(target_os = "linux")]
+    {
+        use std::fs;
+        use std::path::Path;
+
+        // Prüfe Interfaces in /sys/class/net
+        let sysfs = Path::new("/sys/class/net");
+        if let Ok(entries) = fs::read_dir(sysfs) {
+            for entry in entries.flatten() {
+                let ifname = match entry.file_name().into_string() {
+                    Ok(n) => n,
+                    Err(_) => continue,
+                };
+                if ifname == "lo" {
+                    continue;
+                }
+
+                let iface_path = entry.path();
+
+                // 1) operstate == "up"
+                let operstate = fs::read_to_string(iface_path.join("operstate"))
+                    .unwrap_or_default()
+                    .trim()
+                    .to_string();
+                if operstate != "up" {
+                    continue;
+                }
+
+                // 2) carrier == "1" (hat Link)
+                let carrier = fs::read_to_string(iface_path.join("carrier"))
+                    .unwrap_or_default()
+                    .trim()
+                    .to_string();
+                if carrier != "1" {
+                    continue;
+                }
+
+                // 3) Virtuell ausschließen:
+                //    /sys/class/net/<if>/device -> Symlink zu physischer HW;
+                //    zeigt der Pfad unterhalb von ".../virtual/..." oder existiert er gar nicht,
+                //    dann ist das i. d. R. ein virtuelles Interface.
+                let device_link = iface_path.join("device");
+                let is_virtual = match fs::read_link(&device_link) {
+                    Ok(target) => target.as_os_str().to_string_lossy().contains("/virtual/"),
+                    Err(_) => true, // kein device-Link -> in der Regel virtuell
+                };
+                if is_virtual {
+                    continue;
+                }
+
+                // Optional: bekannte „logische“ Typen via Verzeichnis-Erkennung ausschließen
+                // (Bridges, VLANs, Macvlan etc.)
+                if iface_path.join("bridge").exists()
+                    || iface_path.join("bonding").exists()
+                    || iface_path.join("team").exists()
+                    || iface_path.join("vlan").exists()
+                    || iface_path.join("macvlan").exists()
+                {
+                    continue;
+                }
+
+                // Wenn wir hier sind, haben wir eine aktive physische NIC
+                log::log("network_status", "Found active network interface.", LogLevel::Info);
+                return true;
+            }
+        }
+
+        let output = Command::new("ip")
+            .args(["-o", "link", "show", "up"])
+            .output();
+
+        if let Ok(out) = output {
+            if !out.status.success() {
+                return false;
+            }
+            let stdout = String::from_utf8_lossy(&out.stdout);
+            for line in stdout.lines() {
+                if let Some(rest) = line.splitn(2, ": ").nth(1) {
+                    if let Some(ifname) = rest.split(':').next() {
+                        let name = ifname.trim();
+                        if name != "lo" {
+                            log::log("network_status", "Found active network interface.", LogLevel::Info);
+                            return true;
+                        }
+                    }
+                }
+            }
+        }
+        false
+    }
+
+    #[cfg(target_os = "windows")]
+    {
+        // Windows: PowerShell verwenden, um aktive Adapter zu finden (Status = Up).
+        // Wir ignorieren Loopback/Pseudo-Interfaces, indem wir Physical=true filtern.
+        let ps_cmd = r#"
+$adapters = Get-NetAdapter -Physical | Where-Object {$_.Status -eq 'Up'}
+if ($adapters -and $adapters.Count -ge 1) { 'UP' } else { 'DOWN' }
+"#;
+        let output = Command::new("powershell")
+            .args(["-NoProfile", "-NonInteractive", "-Command", ps_cmd])
+            .output();
+
+        if let Ok(out) = output {
+            if !out.status.success() {
+                return false;
+            }
+            let stdout = String::from_utf8_lossy(&out.stdout).to_ascii_uppercase();
+
+            return if stdout.contains("UP") {
+                log::log("network_status", "Found active network interface.", LogLevel::Info);
+                true
+            } else {
+                false
+            }
+        }
+        false
+    }
+
+    #[cfg(not(any(target_os = "linux", target_os = "windows")))]
+    {
+        log::log("network_status", "OS not supported.", LogLevel::Error);
+        false
+    }
+}