README auf aktuellen Funktionsumfang angepasst

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2024 Simple-DHCP-Server contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -18,11 +18,20 @@ Benutze dieses Tool nur in isolierten Testumgebungen oder auf einem dedizierten
   - liest IP & Subnetz des gewählten Interface automatisch aus
   - vergibt Adressen aus einem dynamischen Pool (ab Start-IP)
   - **Neu:** Eingabefelder für Primary/Secondary DNS (DHCP Option 6)
+  - Lease-Time optional per Extended Option 51 oder pro Reservierung
+- **Config-Profiles**: Interface/IP/DNS + Reservierungen/Extended Options als JSON speichern & laden
+- **Statische Reservierungen**: MAC → IP Tabelle in der GUI, wird vom Server beachtet
+- **Leases-Tab**: Restlaufzeit sichtbar, Direkt-Button „Add“ um Leases in Reservierungen zu übernehmen
+- **Force Renew**: DHCPFORCERENEW an alle Hosts im Subnetz auslösen
+- **Optionale PXE-Infos**: DHCP Option 66 (TFTP-Server) und 67 (Bootfile), wenn gesetzt
 - **DHCP-Optionen:**
   - Option 1: Subnetzmaske
   - Option 3: Router/Gateway (setzt automatisch auf Server-IP)
   - Option 6: DNS-Server (aus GUI)
-  - Option 51: Lease-Time
+  - Option 42: NTP-Server (kommagetrennte IPs)
+  - Option 15: DNS-Suffix
+  - Option 51: Lease Time (Pflicht; Default 3600s, override per Extended Options/Reservierung)
+  - Option 66/67: TFTP-Server & Bootfile
 - **Log-Panel & Statusleiste**: zeigt DHCP-Events in Echtzeit
 - **Echte DHCP-Pakete**: DISCOVER → OFFER, REQUEST → ACK, RELEASE → Lease-Freigabe
 
@@ -134,9 +143,10 @@ Leases werden nur im Speicher gehalten (kein persistentes Lease-File).
 ## 🧭 Roadmap
 
 * [ ] Lease-Persistenz (JSON oder SQLite)
-* [ ] Statische MAC-Reservierungen
+* [x] Statische MAC-Reservierungen
+* [x] Mehr Optionen (NTP, PXE, Extended Options)
 * [ ] Konfigurierbarer Pool (Start/End-Adresse)
-* [ ] Mehr Optionen (NTP, PXE, benutzerdefiniert)
+* [ ] Persistente Config-/Lease-Imports für PXE-Labs
 
 ---
 

src/dhcp_server.py

@@ -1,13 +1,16 @@
 import os
+import select
 import socket
 import struct
 import threading
 import time
-import select
 from collections import deque
 from typing import Dict, List, Optional, Tuple
+
 import ipaddress
 
+from utils import normalize_mac
+
 
 MAGIC_COOKIE = b"\x63\x82\x53\x63"
 
@@ -20,8 +23,9 @@ DHCPACK      = 5
 DHCPNAK      = 6
 DHCPRELEASE  = 7
 DHCPINFORM   = 8
+DHCPFORCERENEW = 9
 
-LEASE_SECONDS = 3600  # 1 hour leases
+LEASE_SECONDS = 3600  # default 1 hour leases
 
 
 def mac_bytes_to_str(b: bytes) -> str:
@@ -94,18 +98,32 @@ class DHCPServer:
 
         # NEW: configurable DNS servers for DHCP Option 6
         self.dns_servers: List[str] = []
+        self.reservations: Dict[str, Dict[str, Optional[int]]] = {}  # normalized MAC -> {"ip": str, "lease": Optional[int]}
+        self.extended_options: Dict[str, str] = {}
+        self._network: Optional[ipaddress.IPv4Network] = None
+        self.default_lease_seconds: int = LEASE_SECONDS
 
     # -------------------- Public API --------------------
-    def start(self, interface: str, start_ip: str, mask: str, dns_servers: Optional[List[str]] = None) -> None:
+    def start(
+        self,
+        interface: str,
+        start_ip: str,
+        mask: str,
+        dns_servers: Optional[List[str]] = None,
+        reservations: Optional[List[Dict[str, str]]] = None,
+        extended_options: Optional[Dict[str, Dict[str, str]]] = None,
+    ) -> None:
         if self.is_running():
             raise RuntimeError("Server is already running.")
         self.interface = interface
         self.ip_start = start_ip
         self.subnet_mask = mask
+        self._network = ipaddress.IPv4Network((start_ip, mask), strict=False)
+        self.default_lease_seconds = LEASE_SECONDS
 
         # build pool based on interface network
         self.server_ip = start_ip  # in this lab version we use the provided IP as "server identifier"
-        self._pool = self._build_pool(start_ip, mask)
+        self._pool = self._build_pool(self._network, start_ip)
 
         # configure DNS (filter invalid entries); default to [server_ip, 8.8.8.8]
         self.dns_servers = []
@@ -119,6 +137,25 @@ class DHCPServer:
         if not self.dns_servers and self.server_ip:
             self.dns_servers = [self.server_ip, "8.8.8.8"]
 
+        # static MAC reservations
+        self.reservations = self._prepare_reservations(reservations or [])
+        # extended DHCP options (numeric keyed)
+        self.extended_options = {}
+        if extended_options:
+            for code, data in extended_options.items():
+                val = data.get("value") if isinstance(data, dict) else data
+                if val:
+                    self.extended_options[str(code)] = str(val)
+        # If option 51 is provided, use it as default lease
+        opt51 = self.extended_options.get("51")
+        if opt51:
+            try:
+                lease_int = int(opt51)
+                if lease_int > 0:
+                    self.default_lease_seconds = lease_int
+            except Exception:
+                self._log_line("Extended option 51 ignored (invalid integer).")
+
         self._stop_evt.clear()
         self._thread = threading.Thread(target=self._run_loop, name="DHCPWorker", daemon=True)
         self._thread.start()
@@ -150,6 +187,10 @@ class DHCPServer:
         with self._lock:
             return {mac: ip for mac, (ip, _) in self._leases.items()}
 
+    def get_leases_with_expiry(self) -> Dict[str, Tuple[str, float]]:
+        with self._lock:
+            return {mac: (ip, expiry) for mac, (ip, expiry) in self._leases.items()}
+
     def get_status(self) -> str:
         return self._status
 
@@ -160,6 +201,38 @@ class DHCPServer:
                 items.append(self._log.popleft())
         return items
 
+    def force_renew_all(self) -> int:
+        """
+        Send DHCPFORCERENEW across the subnet (all hosts).
+        Uses known MAC from leases when available; otherwise sends with empty CHADDR.
+        Returns count of attempted sends.
+        """
+        if not self.is_running() or not self._sock:
+            raise RuntimeError("Server not running.")
+        if not self._network:
+            raise RuntimeError("Subnet unbekannt.")
+
+        with self._lock:
+            lease_items = list(self._leases.items())  # (mac, (ip, expiry))
+            lease_by_ip = {ip: mac for mac, (ip, _) in lease_items}
+
+        sent = 0
+        for host in self._network.hosts():
+            ip = str(host)
+            if ip == self.server_ip:
+                continue
+            mac = lease_by_ip.get(ip)
+            pkt = self._build_forcerenew_packet(mac, ip)
+            if not pkt:
+                continue
+            try:
+                self._sock.sendto(pkt, (ip, 68))
+                sent += 1
+            except Exception as e:
+                self._log_line(f"FORCERENEW to {mac}/{ip} failed: {e}")
+        self._log_line(f"FORCERENEW sent to {sent} client(s).")
+        return sent
+
     # -------------------- Internals --------------------
     def _run_loop(self) -> None:
         try:
@@ -238,10 +311,9 @@ class DHCPServer:
                 if mac in self._active_clients:
                     self._active_clients.remove(mac)
 
-    def _build_pool(self, start_ip: str, mask: str) -> List[str]:
+    def _build_pool(self, network: ipaddress.IPv4Network, start_ip: str) -> List[str]:
         # Build pool from the network containing start_ip with provided mask
-        net = ipaddress.IPv4Network((start_ip, mask), strict=False)
-        all_hosts = list(net.hosts())
+        all_hosts = list(network.hosts())
         # Begin at/after start_ip; exclude start_ip (we use it as server/gateway)
         try:
             start_idx = all_hosts.index(ipaddress.IPv4Address(start_ip))
@@ -256,6 +328,61 @@ class DHCPServer:
             pool.remove(start_ip)
         return pool
 
+    def _prepare_reservations(self, reservations: List[Dict[str, str]]) -> Dict[str, Dict[str, Optional[int]]]:
+        prepared: Dict[str, Dict[str, Optional[int]]] = {}
+        for res in reservations:
+            mac_raw = res.get("mac", "")
+            ip = res.get("ip", "")
+            lease = res.get("lease_time")
+            try:
+                lease_int = int(lease) if lease not in (None, "") else None
+                if lease_int is not None and lease_int <= 0:
+                    lease_int = None
+            except Exception:
+                lease_int = None
+            try:
+                mac_norm = normalize_mac(mac_raw)
+            except Exception:
+                self._log_line(f"Ignoring reservation '{mac_raw}': invalid MAC")
+                continue
+            try:
+                ip_norm = str(ipaddress.IPv4Address(ip))
+            except Exception:
+                self._log_line(f"Ignoring reservation {mac_norm}: invalid IP '{ip}'")
+                continue
+            if ip_norm == self.server_ip:
+                self._log_line(f"Ignoring reservation {mac_norm}: IP {ip_norm} is server IP")
+                continue
+            if self._network and ipaddress.IPv4Address(ip_norm) not in self._network:
+                self._log_line(f"Ignoring reservation {mac_norm}: IP {ip_norm} not in subnet")
+                continue
+            prepared[mac_norm] = {"ip": ip_norm, "lease": lease_int}
+            if ip_norm in self._pool:
+                self._pool.remove(ip_norm)
+        return prepared
+
+    def _reserved_ip_for(self, mac: str) -> Optional[str]:
+        entry = self.reservations.get(mac.upper())
+        return entry["ip"] if entry else None
+
+    def _reserved_lease_for(self, mac: str) -> Optional[int]:
+        entry = self.reservations.get(mac.upper())
+        return entry.get("lease") if entry else None
+
+    def _is_ip_available(self, ip: Optional[str], mac: str) -> bool:
+        if not ip:
+            return False
+        # Reserved for different MAC?
+        for res_mac, res in self.reservations.items():
+            res_ip = res.get("ip")
+            if res_ip == ip and res_mac != mac:
+                return False
+        with self._lock:
+            for lease_mac, (lease_ip, _) in self._leases.items():
+                if lease_ip == ip and lease_mac != mac:
+                    return False
+        return True
+
     def _next_free_ip(self) -> Optional[str]:
         with self._lock:
             used = {ip for ip, _ in self._leases.values()}
@@ -309,37 +436,62 @@ class DHCPServer:
             pass
 
     def _dhcp_offer(self, mac: str, xid: int, giaddr: bytes) -> None:
+        reserved_ip = self._reserved_ip_for(mac)
+        lease_seconds = self._reserved_lease_for(mac) or self.default_lease_seconds
+        if reserved_ip and self._is_ip_available(reserved_ip, mac):
+            ip = reserved_ip
+        else:
             ip = self._next_free_ip()
         if not ip:
             self._log_line("No free IP to offer.")
             return
+        if reserved_ip:
+            self._log_line(f"OFFER (reserved) {ip} to {mac}")
+        else:
             self._log_line(f"OFFER {ip} to {mac}")
         pkt = self._build_reply_packet(
-            msg_type=DHCPOFFER, mac=mac, xid=xid, yiaddr=ip, giaddr=giaddr
+            msg_type=DHCPOFFER, mac=mac, xid=xid, yiaddr=ip, giaddr=giaddr, lease_seconds=lease_seconds
         )
         self._send_broadcast(pkt)
 
     def _dhcp_ack(self, mac: str, xid: int, giaddr: bytes, requested_ip: Optional[str]) -> None:
         # If requested IP is available or already leased to this MAC, use it; else choose next free
+        reserved_ip = self._reserved_ip_for(mac)
+        lease_seconds = self._reserved_lease_for(mac) or self.default_lease_seconds
+        if reserved_ip and not self._is_ip_available(reserved_ip, mac):
+            reserved_ip = None
+
         with self._lock:
             current = self._leases.get(mac, (None, 0))[0]
-        ip = requested_ip or current or self._next_free_ip()
+        ip: Optional[str] = None
+        if reserved_ip:
+            ip = reserved_ip
+        elif requested_ip and self._is_ip_available(requested_ip, mac):
+            ip = requested_ip
+        elif current and self._is_ip_available(current, mac):
+            ip = current
+        else:
+            ip = self._next_free_ip()
+
         if not ip:
             self._log_line("No IP available for ACK.")
             return
         # Register/renew lease
-        expiry = time.time() + LEASE_SECONDS
+        expiry = time.time() + lease_seconds
         with self._lock:
             self._leases[mac] = (ip, expiry)
             if mac not in self._active_clients:
                 self._active_clients.append(mac)
+        if reserved_ip:
+            self._log_line(f"ACK (reserved) {ip} to {mac}")
+        else:
             self._log_line(f"ACK {ip} to {mac}")
         pkt = self._build_reply_packet(
-            msg_type=DHCPACK, mac=mac, xid=xid, yiaddr=ip, giaddr=giaddr
+            msg_type=DHCPACK, mac=mac, xid=xid, yiaddr=ip, giaddr=giaddr, lease_seconds=lease_seconds
         )
         self._send_broadcast(pkt)
 
-    def _build_reply_packet(self, msg_type: int, mac: str, xid: int, yiaddr: str, giaddr: bytes) -> bytes:
+    def _build_reply_packet(self, msg_type: int, mac: str, xid: int, yiaddr: str, giaddr: bytes, lease_seconds: int) -> bytes:
         # BOOTP header
         op = 2  # reply
         htype = 1
@@ -374,8 +526,52 @@ class DHCPServer:
             dns_bytes = b"".join(ip2bytes(ip) for ip in self.dns_servers)
             options.append((6, dns_bytes))
 
-        options.append((51, struct.pack("!I", LEASE_SECONDS)))     # lease time
+        # Numeric extended options
+        for code_str, val in self.extended_options.items():
+            try:
+                code = int(code_str)
+            except Exception:
+                self._log_line(f"Ignoring extended option with non-numeric code '{code_str}'")
+                continue
+            opt_bytes = self._encode_extended_option(code, val)
+            if opt_bytes is None:
+                continue
+            options.append((code, opt_bytes))
 
+        options.append((51, struct.pack("!I", lease_seconds)))     # lease time
+
+        return hdr + build_options(options)
+
+    def _build_forcerenew_packet(self, mac: Optional[str], client_ip: str) -> Optional[bytes]:
+        """Minimal FORCERENEW per RFC 3203 to trigger clients to renew."""
+        try:
+            ciaddr = ip2bytes(client_ip)
+        except Exception:
+            return None
+        op = 2
+        htype = 1
+        hlen = 6 if mac else 0
+        hops = 0
+        xid = 0
+        secs = 0
+        flags = 0
+        yiaddr_b = b"\x00\x00\x00\x00"
+        siaddr = ip2bytes(self.server_ip or "0.0.0.0")
+        giaddr_b = b"\x00\x00\x00\x00"
+        chaddr = (
+            bytes.fromhex(mac.replace(":", "")) + b"\x00" * 10
+            if mac
+            else b"\x00" * 16
+        )
+        sname = b"\x00" * 64
+        filef = b"\x00" * 128
+        hdr = struct.pack("!BBBBIHH4s4s4s4s16s64s128s",
+                          op, htype, hlen, hops, xid, secs, flags,
+                          ciaddr, yiaddr_b, siaddr, giaddr_b, chaddr, sname, filef)
+        options = [
+            (53, bytes([DHCPFORCERENEW])),
+            (54, siaddr),
+        ]
         return hdr + build_options(options)
 
     def _send_broadcast(self, pkt: bytes) -> None:
@@ -393,3 +589,34 @@ class DHCPServer:
 
     def _set_status(self, st: str) -> None:
         self._status = st
+
+    def _encode_extended_option(self, code: int, value: str) -> Optional[bytes]:
+        if not value:
+            return None
+        if code == 42:
+            # NTP servers as comma-separated IP list
+            parts = [p.strip() for p in value.split(",") if p.strip()]
+            ips = []
+            for p in parts:
+                try:
+                    ips.append(ip2bytes(p))
+                except Exception:
+                    continue
+            if not ips:
+                self._log_line("Extended option 42 skipped (no valid IPs).")
+                return None
+            return b"".join(ips)
+        if code == 51:
+            try:
+                lease_int = int(value)
+                if lease_int <= 0:
+                    return None
+                return struct.pack("!I", lease_int)
+            except Exception:
+                self._log_line("Extended option 51 ignored (invalid integer).")
+                return None
+        try:
+            return value.encode("ascii")
+        except Exception:
+            self._log_line(f"Extended option {code} not sent (invalid encoding).")
+            return None

src/gui.py

@@ -1,10 +1,14 @@
+import ipaddress
+import json
 import os
 import socket
+import time
 import tkinter as tk
-from tkinter import messagebox, ttk
-from typing import Optional, List
+from tkinter import filedialog, messagebox, ttk
+from typing import Dict, List, Optional, Tuple
 
 from dhcp_server import DHCPServer
+from option_specs import EXTENDED_OPTION_SPECS
 import utils
 
 
@@ -55,86 +59,236 @@ class DHCPApp(tk.Frame):
     def __init__(self, master: tk.Tk) -> None:
         super().__init__(master)
         master.title("Simple DHCP Server (Lab)")
-        master.minsize(700, 500)
         self.pack(fill="both", expand=True, padx=12, pady=12)
 
         # Single server instance
         self.server: Optional[DHCPServer] = None
+        self.reservations: List[Dict[str, str]] = []
+        self.last_config_path: Optional[str] = None
+        self.ext_option_specs = list(EXTENDED_OPTION_SPECS)
+        self.ext_opt_values: Dict[str, tk.StringVar] = {}
+        self.ext_opt_enabled: Dict[str, tk.BooleanVar] = {}
 
-        # --- Top form ---
-        form = ttk.Frame(self)
-        form.pack(fill="x", pady=(0, 8))
+        # --- Toolbar ---
+        toolbar = ttk.Frame(self)
+        toolbar.pack(fill="x", pady=(0, 6))
+        self.btn_start = ttk.Button(toolbar, text="Start", command=self.start_server)
+        self.btn_stop = ttk.Button(toolbar, text="Stop", command=self.stop_server, state="disabled")
+        self.btn_rescan = ttk.Button(toolbar, text="Interfaces neu scannen", command=self.rescan_interfaces)
+        self.btn_load = ttk.Button(toolbar, text="Config laden", command=self.load_config)
+        self.btn_save = ttk.Button(toolbar, text="Config speichern", command=self.save_config)
+        self.btn_forcerenew = ttk.Button(toolbar, text="Force Renew", command=self.force_renew_all)
+        self.btn_start.pack(side="left", padx=(0, 6))
+        self.btn_stop.pack(side="left", padx=(0, 12))
+        self.btn_rescan.pack(side="left", padx=(0, 12))
+        self.btn_load.pack(side="left", padx=(0, 6))
+        self.btn_save.pack(side="left")
+        self.btn_forcerenew.pack(side="left", padx=(12, 0))
 
-        # Zeile 0
-        ttk.Label(form, text="Interface:").grid(row=0, column=0, sticky="w")
+        # --- Interface left, IP settings right ---
+        top = ttk.Frame(self)
+        top.pack(fill="x", pady=(0, 10), anchor="w")
+
+        # Left: Interface box with dropdown + info
+        iface_box = ttk.Labelframe(top, text="Interface")
+        iface_box.pack(side="left", padx=(0, 8), fill="y")
+        iface_box.update_idletasks()
+        iface_box.configure(width=400)
+        iface_box.pack_propagate(False)
+        iface_box.columnconfigure(1, weight=1)
+
+        ttk.Label(iface_box, text="Interface:").grid(row=0, column=0, sticky="w", padx=(8, 4), pady=(8, 6))
         self.if_var = tk.StringVar()
-        self.if_menu = ttk.OptionMenu(form, self.if_var, None, *utils.get_network_interfaces(), command=self.on_iface_change)
-        self.if_menu.grid(row=0, column=1, sticky="ew", padx=(6, 16))
-        form.columnconfigure(1, weight=1)
+        self.if_combo = ttk.Combobox(iface_box, textvariable=self.if_var, state="readonly", width=18)
+        self.if_combo.grid(row=0, column=1, sticky="ew", padx=(4, 8), pady=(8, 6))
+        self.if_combo.bind("<<ComboboxSelected>>", self.on_iface_change)
 
-        ttk.Label(form, text="Server/Start-IP:").grid(row=0, column=2, sticky="w")
+        self.mac_var = tk.StringVar(value="-")
+        self.speed_var = tk.StringVar(value="-")
+        ttk.Label(iface_box, text="MAC:").grid(row=1, column=0, sticky="w", padx=(8, 4), pady=(2, 8))
+        ttk.Label(iface_box, textvariable=self.mac_var).grid(row=1, column=1, sticky="w", padx=(4, 8), pady=(2, 8))
+        ttk.Label(iface_box, text="Link:").grid(row=2, column=0, sticky="w", padx=(8, 4), pady=(0, 10))
+        ttk.Label(iface_box, textvariable=self.speed_var).grid(row=2, column=1, sticky="w", padx=(4, 8), pady=(0, 10))
+
+        # Right: IP settings box
+        ip_box = ttk.Labelframe(top, text="IP-Settings")
+        ip_box.pack(side="left", fill="y")
+        ip_box.update_idletasks()
+        ip_box.configure(width=420)
+        ip_box.pack_propagate(False)
+        ip_box.columnconfigure(1, weight=1)
+        ip_box.columnconfigure(3, weight=1)
+
+        ttk.Label(ip_box, text="Server/Start-IP:").grid(row=0, column=0, sticky="w", padx=(8, 4), pady=(8, 4))
         self.ip_var = tk.StringVar(value="")
-        self.ip_entry = ttk.Entry(form, textvariable=self.ip_var, width=16)
-        self.ip_entry.grid(row=0, column=3, sticky="w", padx=(6, 16))
+        self.ip_entry = ttk.Entry(ip_box, textvariable=self.ip_var, width=16)
+        self.ip_entry.grid(row=0, column=1, sticky="w", padx=(4, 12), pady=(8, 4))
 
-        ttk.Label(form, text="Subnetzmaske:").grid(row=0, column=4, sticky="w")
+        ttk.Label(ip_box, text="Subnetzmaske:").grid(row=0, column=2, sticky="w", padx=(8, 4), pady=(8, 4))
         self.mask_var = tk.StringVar(value="")
-        self.mask_entry = ttk.Entry(form, textvariable=self.mask_var, width=16)
-        self.mask_entry.grid(row=0, column=5, sticky="w", padx=(6, 16))
+        self.mask_entry = ttk.Entry(ip_box, textvariable=self.mask_var, width=16)
+        self.mask_entry.grid(row=0, column=3, sticky="w", padx=(4, 12), pady=(8, 4))
 
-        # Zeile 1 – DNS Felder
-        ttk.Label(form, text="Primary DNS:").grid(row=1, column=0, sticky="w", pady=(6, 0))
+        ttk.Label(ip_box, text="Primary DNS:").grid(row=1, column=0, sticky="w", padx=(8, 4), pady=(4, 10))
         self.dns1_var = tk.StringVar(value="")
-        self.dns1_entry = ttk.Entry(form, textvariable=self.dns1_var, width=16)
-        self.dns1_entry.grid(row=1, column=1, sticky="w", padx=(6, 16), pady=(6, 0))
+        self.dns1_entry = ttk.Entry(ip_box, textvariable=self.dns1_var, width=16)
+        self.dns1_entry.grid(row=1, column=1, sticky="w", padx=(4, 12), pady=(4, 10))
 
-        ttk.Label(form, text="Secondary DNS:").grid(row=1, column=2, sticky="w", pady=(6, 0))
+        ttk.Label(ip_box, text="Secondary DNS:").grid(row=1, column=2, sticky="w", padx=(8, 4), pady=(4, 10))
         self.dns2_var = tk.StringVar(value="")
-        self.dns2_entry = ttk.Entry(form, textvariable=self.dns2_var, width=16)
-        self.dns2_entry.grid(row=1, column=3, sticky="w", padx=(6, 16), pady=(6, 0))
+        self.dns2_entry = ttk.Entry(ip_box, textvariable=self.dns2_var, width=16)
+        self.dns2_entry.grid(row=1, column=3, sticky="w", padx=(4, 12), pady=(4, 10))
 
-        # --- Buttons ---
-        btns = ttk.Frame(self)
-        btns.pack(fill="x", pady=(8, 8))
-        self.btn_start = ttk.Button(btns, text="Start", command=self.start_server)
-        self.btn_stop = ttk.Button(btns, text="Stop", command=self.stop_server, state="disabled")
-        self.btn_start.pack(side="left")
-        self.btn_stop.pack(side="left", padx=(8, 0))
-
-        # --- Clients & Logs Paned Layout ---
-        paned = ttk.Panedwindow(self, orient="horizontal")
-        paned.pack(fill="both", expand=True)
-
-        # Clients list
-        left = ttk.Labelframe(paned, text="Aktive Clients / Leases")
-        self.clients = tk.Listbox(left, height=12)
-        self.clients.pack(fill="both", expand=True, padx=6, pady=6)
-        paned.add(left, weight=1)
-
-        # Logs
-        right = ttk.Labelframe(paned, text="Log")
-        self.log = tk.Text(right, height=12, state="disabled")
-        self.log.pack(fill="both", expand=True, padx=6, pady=6)
-        paned.add(right, weight=2)
+        # --- Notebook with tabs ---
+        self._build_tabs()
 
         # --- Status bar ---
         self.status_var = tk.StringVar(value="Bereit.")
         status = ttk.Label(self, textvariable=self.status_var, anchor="w", relief="sunken")
         status.pack(fill="x", side="bottom")
 
-        # initial iface autofill (if any interface exists)
-        ifaces = utils.get_network_interfaces()
-        if ifaces:
-            self.if_var.set(ifaces[0])
-            self.on_iface_change(ifaces[0])
+        self._refresh_interface_list(initial=True)
+        self._apply_min_sizes()
+
+        # keep disabled option display in sync with GUI IP/DNS
+        for v in (self.ip_var, self.mask_var, self.dns1_var, self.dns2_var):
+            v.trace_add("write", lambda *_: self._refresh_disabled_ext_options())
+        self._refresh_disabled_ext_options()
 
         # periodic refresh
         self.after(400, self._refresh)
 
+    # -------------------- UI builders --------------------
+    def _build_tabs(self) -> None:
+        self.notebook = ttk.Notebook(self)
+        self.notebook.pack(fill="both", expand=True)
+
+        self._build_lease_tab()
+        self._build_log_tab()
+        self._build_reservations_tab()
+        self._build_extended_options_tab()
+
+    def _build_lease_tab(self) -> None:
+        tab = ttk.Frame(self.notebook)
+        columns = ("mac", "ip", "remaining", "action")
+        self.leases_tree = ttk.Treeview(tab, columns=columns, show="headings", height=10)
+        self.leases_tree.heading("mac", text="MAC-Adresse")
+        self.leases_tree.heading("ip", text="IP-Adresse")
+        self.leases_tree.heading("remaining", text="Restlaufzeit")
+        self.leases_tree.heading("action", text="Reservierung")
+        self.leases_tree.column("mac", width=160, anchor="w")
+        self.leases_tree.column("ip", width=140, anchor="w")
+        self.leases_tree.column("remaining", width=120, anchor="w")
+        self.leases_tree.column("action", width=120, anchor="w")
+        scroll = ttk.Scrollbar(tab, orient="vertical", command=self.leases_tree.yview)
+        self.leases_tree.configure(yscrollcommand=scroll.set)
+        self.leases_tree.pack(side="left", fill="both", expand=True, padx=6, pady=6)
+        scroll.pack(side="right", fill="y")
+        self.leases_tree.bind("<ButtonRelease-1>", self._on_lease_click)
+        self.notebook.add(tab, text="Leases")
+
+    def _build_log_tab(self) -> None:
+        tab = ttk.Frame(self.notebook)
+        self.log = tk.Text(tab, height=12, state="disabled")
+        scroll = ttk.Scrollbar(tab, orient="vertical", command=self.log.yview)
+        self.log.configure(yscrollcommand=scroll.set)
+        self.log.pack(side="left", fill="both", expand=True, padx=6, pady=6)
+        scroll.pack(side="right", fill="y")
+        self.notebook.add(tab, text="Log")
+
+    def _build_reservations_tab(self) -> None:
+        tab = ttk.Frame(self.notebook)
+
+        tree_frame = ttk.Frame(tab)
+        tree_frame.pack(fill="both", expand=True, padx=6, pady=6)
+        columns = ("mac", "ip", "lease", "name")
+        self.res_tree = ttk.Treeview(tree_frame, columns=columns, show="headings", selectmode="extended", height=8)
+        self.res_tree.heading("mac", text="MAC-Adresse")
+        self.res_tree.heading("ip", text="IP-Adresse")
+        self.res_tree.heading("lease", text="Lease (s)")
+        self.res_tree.heading("name", text="Name/Notiz")
+        self.res_tree.column("mac", width=150, anchor="w")
+        self.res_tree.column("ip", width=140, anchor="w")
+        self.res_tree.column("lease", width=90, anchor="w")
+        self.res_tree.column("name", width=200, anchor="w")
+        scroll = ttk.Scrollbar(tree_frame, orient="vertical", command=self.res_tree.yview)
+        self.res_tree.configure(yscrollcommand=scroll.set)
+        self.res_tree.pack(side="left", fill="both", expand=True)
+        scroll.pack(side="right", fill="y")
+        self.res_tree.bind("<<TreeviewSelect>>", self._on_reservation_select)
+
+        form = ttk.Labelframe(tab, text="Eintrag bearbeiten")
+        form.pack(fill="x", padx=6, pady=(0, 8))
+
+        ttk.Label(form, text="MAC:").grid(row=0, column=0, sticky="w", padx=(6, 2), pady=4)
+        self.res_mac_var = tk.StringVar()
+        ttk.Entry(form, textvariable=self.res_mac_var, width=22).grid(row=0, column=1, sticky="w", pady=4)
+
+        ttk.Label(form, text="IP:").grid(row=0, column=2, sticky="w", padx=(12, 2), pady=4)
+        self.res_ip_var = tk.StringVar()
+        ttk.Entry(form, textvariable=self.res_ip_var, width=18).grid(row=0, column=3, sticky="w", pady=4)
+
+        ttk.Label(form, text="Lease (s):").grid(row=0, column=4, sticky="w", padx=(12, 2), pady=4)
+        self.res_lease_var = tk.StringVar()
+        ttk.Entry(form, textvariable=self.res_lease_var, width=10).grid(row=0, column=5, sticky="w", pady=4)
+
+        ttk.Label(form, text="Name/Notiz:").grid(row=0, column=6, sticky="w", padx=(12, 2), pady=4)
+        self.res_name_var = tk.StringVar()
+        ttk.Entry(form, textvariable=self.res_name_var, width=22).grid(row=0, column=7, sticky="w", pady=4)
+
+        actions = ttk.Frame(form)
+        actions.grid(row=0, column=8, sticky="e", padx=(12, 6))
+        ttk.Button(actions, text="Hinzufügen/Aktualisieren", command=self.add_or_update_reservation).pack(side="left", padx=(0, 6))
+        ttk.Button(actions, text="Löschen", command=self.remove_reservation).pack(side="left")
+
+        self.notebook.add(tab, text="Reservierungen")
+
+    def _build_extended_options_tab(self) -> None:
+        tab = ttk.Frame(self.notebook)
+
+        form = ttk.Frame(tab)
+        form.pack(fill="x", padx=8, pady=(8, 8))
+        ttk.Label(form, text="Aktiv").grid(row=0, column=0, sticky="w", padx=(0, 12))
+        ttk.Label(form, text="Option").grid(row=0, column=1, sticky="w", padx=(0, 12))
+        ttk.Label(form, text="Wert").grid(row=0, column=2, sticky="w", padx=(0, 12))
+        ttk.Label(form, text="Beschreibung").grid(row=0, column=3, sticky="w", padx=(0, 12))
+        form.columnconfigure(3, weight=1)
+
+        row = 1
+        for spec in self.ext_option_specs:
+            code = spec["code"]
+            default_val = spec.get("default", "")
+            mandatory = bool(spec.get("mandatory"))
+            self.ext_opt_values[code] = tk.StringVar(value=default_val)
+            self.ext_opt_enabled[code] = tk.BooleanVar(value=mandatory)
+            disabled = bool(spec.get("disabled"))
+            desc_txt = spec.get("desc", "")
+            if disabled:
+                desc_txt = f"{desc_txt} (aus GUI/Server, gesperrt)"
+
+            chk = ttk.Checkbutton(form, variable=self.ext_opt_enabled[code])
+            if disabled:
+                chk.state(["disabled"])
+            chk.grid(row=row, column=0, sticky="w", pady=4)
+            ttk.Label(form, text=code).grid(row=row, column=1, sticky="w", pady=4)
+            entry = ttk.Entry(form, textvariable=self.ext_opt_values[code], width=32, state="disabled" if disabled else "normal")
+            entry.grid(row=row, column=2, sticky="w", padx=(0, 12), pady=4)
+            ttk.Label(form, text=desc_txt).grid(row=row, column=3, sticky="w", padx=(0, 12), pady=4)
+            row += 1
+
+        ttk.Label(tab, text="Weitere Optionen kannst du in option_specs.py ergänzen.").pack(anchor="w", padx=8, pady=(4, 8))
+
+        self.notebook.add(tab, text="Extended Options")
+
     # -------------------- UI logic --------------------
     def on_iface_change(self, _sel=None):
         iface = self.if_var.get().strip()
+        if not iface:
+            self._clear_iface_fields()
+            return
+
         ip, mask = utils.get_iface_ipv4_config(iface)
+        self._clear_iface_fields()
         if ip:
             self.ip_var.set(ip)
             # sinnvolles Default: Primary DNS = Interface-IP
@@ -142,16 +296,78 @@ class DHCPApp(tk.Frame):
         if mask:
             self.mask_var.set(mask)
         # Secondary DNS bleibt leer, damit du frei wählen kannst
+        self._update_iface_info(iface)
 
     def _set_controls_enabled(self, enabled: bool):
-        state = "normal" if enabled else "disabled"
-        self.if_menu.configure(state=state)
+        state = "readonly" if enabled else "disabled"
+        self.if_combo.configure(state=state)
         self.ip_entry.configure(state=state)
         self.mask_entry.configure(state=state)
         self.dns1_entry.configure(state=state)
         self.dns2_entry.configure(state=state)
+        self.btn_rescan.configure(state=state)
         self.btn_start.configure(state="normal" if enabled else "disabled")
         self.btn_stop.configure(state="disabled" if enabled else "normal")
+        self.btn_forcerenew.configure(state="disabled" if enabled else "normal")
+
+    def _clear_iface_fields(self) -> None:
+        self.ip_var.set("")
+        self.mask_var.set("")
+        self.dns1_var.set("")
+        self.dns2_var.set("")
+        self.mac_var.set("-")
+        self.speed_var.set("-")
+        self._refresh_disabled_ext_options()
+
+    def _select_iface(self, iface: str) -> None:
+        self.if_var.set(iface)
+        self.on_iface_change()
+
+    def _refresh_interface_list(self, initial: bool = False) -> None:
+        interfaces = utils.get_network_interfaces()
+        current = self.if_var.get().strip()
+        self.if_combo["values"] = interfaces
+
+        if current in interfaces:
+            selection = current
+        elif interfaces:
+            selection = interfaces[0]
+        else:
+            selection = ""
+
+        if selection:
+            self._select_iface(selection)
+            if not initial:
+                self.status_var.set(f"{len(interfaces)} Interface(s) geladen.")
+        else:
+            self.if_var.set("")
+            self._clear_iface_fields()
+            if not initial:
+                self.status_var.set("Keine Netzwerk-Interfaces gefunden.")
+        if selection:
+            self._update_iface_info(selection)
+        self._refresh_disabled_ext_options()
+
+    def _apply_min_sizes(self) -> None:
+        # Ensure window cannot shrink below a comfortable layout
+        self.update_idletasks()
+        min_w = max(self.winfo_reqwidth() + 16, 840)
+        min_h = max(self.winfo_reqheight() + 16, 580)
+        self.master.minsize(min_w, min_h)
+
+    def _update_iface_info(self, iface: str) -> None:
+        mac, speed = utils.get_iface_hwinfo(iface)
+        self.mac_var.set(mac or "-")
+        if speed is None or speed <= 0:
+            self.speed_var.set("-")
+        else:
+            self.speed_var.set(f"{speed} Mbit/s")
+
+    def rescan_interfaces(self) -> None:
+        if self.server and self.server.is_running():
+            messagebox.showinfo("Server läuft", "Stoppe den Server, bevor du Interfaces neu scannst.")
+            return
+        self._refresh_interface_list()
 
     def start_server(self) -> None:
         if self.server and self.server.is_running():
@@ -196,13 +412,28 @@ class DHCPApp(tk.Frame):
             messagebox.showerror("Start fehlgeschlagen (Bind)", f"Konnte Port 67 auf {iface} nicht binden:\n{e}")
             return
 
+        reservations = self._get_reservation_dict()
+        extended_opts = self._collect_extended_options()
+        try:
+            self._ensure_mandatory_ext_options(fail_on_missing=True)
+        except Exception as e:
+            messagebox.showerror("Pflicht-Option fehlt", str(e))
+            return
+
         # --- Start ---
         try:
             self.server = DHCPServer()
-            # NEU: DNS-Liste an den Server übergeben
-            self.server.start(iface, ip, mask, dns_servers=dns_list)
+            self.server.start(
+                iface,
+                ip,
+                mask,
+                dns_servers=dns_list,
+                reservations=reservations,
+                extended_options=extended_opts,
+            )
             self.status_var.set("Server gestartet.")
             self._set_controls_enabled(False)
+            self.btn_forcerenew.configure(state="normal")
         except Exception as e:
             self.server = None
             self.status_var.set("Start fehlgeschlagen.")
@@ -212,8 +443,208 @@ class DHCPApp(tk.Frame):
         if self.server:
             self.server.stop()
         self._set_controls_enabled(True)
+        self.btn_forcerenew.configure(state="disabled")
         self.status_var.set("Server gestoppt.")
 
+    # -------------------- Reservations --------------------
+    def _refresh_reservations_view(self) -> None:
+        for item in self.res_tree.get_children():
+            self.res_tree.delete(item)
+        for entry in self.reservations:
+            lease_raw = entry.get("lease_time", "")
+            lease = lease_raw if lease_raw is not None else ""
+            self.res_tree.insert("", "end", values=(entry.get("mac", ""), entry.get("ip", ""), lease, entry.get("name", "")))
+
+    def add_or_update_reservation(self) -> None:
+        mac = self.res_mac_var.get().strip()
+        ip = self.res_ip_var.get().strip()
+        lease = self.res_lease_var.get().strip()
+        name = self.res_name_var.get().strip()
+        if not mac or not ip:
+            messagebox.showerror("Fehler", "MAC und IP sind erforderlich.")
+            return
+        try:
+            mac_norm = utils.normalize_mac(mac)
+            ip_norm = utils.format_ip_address(ip)
+            lease_val = None
+            if lease:
+                lease_int = int(lease)
+                if lease_int <= 0:
+                    raise ValueError("Lease muss > 0 sein.")
+                lease_val = lease_int
+        except Exception as e:
+            messagebox.showerror("Ungültige Eingabe", str(e))
+            return
+
+        existing = next((r for r in self.reservations if r.get("mac") == mac_norm), None)
+        if existing:
+            existing.update({"ip": ip_norm, "name": name, "lease_time": lease_val})
+        else:
+            self.reservations.append({"mac": mac_norm, "ip": ip_norm, "name": name, "lease_time": lease_val})
+        self._refresh_reservations_view()
+
+    def remove_reservation(self) -> None:
+        selected = self.res_tree.selection()
+        if not selected:
+            return
+        macs = {self.res_tree.item(item, "values")[0] for item in selected}
+        self.reservations = [r for r in self.reservations if r.get("mac") not in macs]
+        self._refresh_reservations_view()
+
+    def _on_reservation_select(self, _event=None) -> None:
+        selected = self.res_tree.selection()
+        if not selected:
+            return
+        vals = self.res_tree.item(selected[0], "values")
+        if vals:
+            self.res_mac_var.set(vals[0])
+            self.res_ip_var.set(vals[1])
+            self.res_lease_var.set(vals[2])
+            self.res_name_var.set(vals[3] if len(vals) > 3 else "")
+
+    def _get_reservation_dict(self) -> List[Dict[str, str]]:
+        return [
+            {
+                "mac": entry["mac"],
+                "ip": entry["ip"],
+                "name": entry.get("name", ""),
+                "lease_time": entry.get("lease_time"),
+            }
+            for entry in self.reservations
+            if entry.get("mac") and entry.get("ip")
+        ]
+
+    def _has_reservation(self, mac: str) -> bool:
+        return any(r.get("mac") == mac for r in self.reservations)
+
+    # -------------------- Extended Options --------------------
+    def _collect_extended_options(self) -> Dict[str, str]:
+        opts: Dict[str, Dict[str, str]] = {}
+        for spec in self.ext_option_specs:
+            code = spec["code"]
+            if spec.get("disabled"):
+                continue
+            val = (self.ext_opt_values.get(code) or tk.StringVar()).get().strip()
+            enabled = bool((self.ext_opt_enabled.get(code) or tk.BooleanVar()).get())
+            if spec.get("mandatory") and not val:
+                continue
+            if (enabled or spec.get("mandatory")) and val:
+                opts[code] = {"value": val, "enabled": True}
+        return opts
+
+    # -------------------- Config load/save --------------------
+    def _collect_config(self) -> Dict:
+        dns_entries = [d for d in (self.dns1_var.get().strip(), self.dns2_var.get().strip()) if d]
+        return {
+            "interface": self.if_var.get().strip(),
+            "server_ip": self.ip_var.get().strip(),
+            "subnet_mask": self.mask_var.get().strip(),
+            "dns": dns_entries,
+            "reservations": self.reservations,
+            "extended_options": {
+                spec["code"]: {
+                    "value": (self.ext_opt_values[spec["code"]].get().strip()),
+                    "enabled": bool(self.ext_opt_enabled[spec["code"]].get()),
+                }
+                for spec in self.ext_option_specs
+                if not spec.get("disabled")
+            },
+        }
+
+    def _apply_config(self, cfg: Dict) -> None:
+        self.if_var.set(cfg.get("interface", ""))
+        self.ip_var.set(cfg.get("server_ip", ""))
+        self.mask_var.set(cfg.get("subnet_mask", ""))
+        dns = cfg.get("dns") or []
+        self.dns1_var.set(dns[0] if len(dns) > 0 else "")
+        self.dns2_var.set(dns[1] if len(dns) > 1 else "")
+        self._refresh_disabled_ext_options()
+
+        # reservations
+        self.reservations = []
+        for item in cfg.get("reservations") or []:
+            mac = item.get("mac") or ""
+            ip = item.get("ip") or ""
+            name = item.get("name") or ""
+            lease_time = item.get("lease_time")
+            try:
+                lease_time = int(lease_time) if lease_time not in (None, "", "None") else None
+                if lease_time is not None and lease_time <= 0:
+                    lease_time = None
+            except Exception:
+                lease_time = None
+            try:
+                mac_norm = utils.normalize_mac(mac)
+                ip_norm = utils.format_ip_address(ip)
+            except Exception:
+                continue
+            self.reservations.append({"mac": mac_norm, "ip": ip_norm, "name": name, "lease_time": lease_time})
+        self._refresh_reservations_view()
+
+        ext = cfg.get("extended_options") or {}
+        # First clear
+        for code in self.ext_option_specs:
+            default_val = code.get("default", "")
+            self.ext_opt_values[code["code"]].set(default_val)
+            self.ext_opt_enabled[code["code"]].set(bool(code.get("mandatory")))
+        self._refresh_disabled_ext_options()
+
+        # Apply values if present (numeric keys preferred)
+        for code in self.ext_option_specs:
+            c = code["code"]
+            if code.get("disabled"):
+                continue
+            entry = ext.get(c)
+            if entry is None:
+                continue
+            if isinstance(entry, dict):
+                self.ext_opt_values[c].set(entry.get("value", "") or code.get("default", ""))
+                self.ext_opt_enabled[c].set(bool(entry.get("enabled")) or bool(code.get("mandatory")))
+            else:
+                self.ext_opt_values[c].set(str(entry))
+                self.ext_opt_enabled[c].set(True)
+
+        # Enforce mandatory defaults if still empty
+        self._ensure_mandatory_ext_options(fail_on_missing=False)
+
+    def load_config(self) -> None:
+        path = filedialog.askopenfilename(
+            title="Config laden",
+            filetypes=[("JSON", "*.json"), ("Alle Dateien", "*.*")],
+            initialfile=os.path.basename(self.last_config_path or ""),
+        )
+        if not path:
+            return
+        try:
+            with open(path, "r", encoding="utf-8") as f:
+                cfg = json.load(f)
+        except Exception as e:
+            messagebox.showerror("Fehler beim Laden", str(e))
+            return
+        self._apply_config(cfg)
+        self.last_config_path = path
+        self.status_var.set(f"Config geladen: {os.path.basename(path)}")
+
+    def save_config(self) -> None:
+        path = filedialog.asksaveasfilename(
+            title="Config speichern",
+            defaultextension=".json",
+            filetypes=[("JSON", "*.json"), ("Alle Dateien", "*.*")],
+            initialfile=os.path.basename(self.last_config_path or "dhcp_config.json"),
+        )
+        if not path:
+            return
+        cfg = self._collect_config()
+        try:
+            with open(path, "w", encoding="utf-8") as f:
+                json.dump(cfg, f, indent=2)
+        except Exception as e:
+            messagebox.showerror("Fehler beim Speichern", str(e))
+            return
+        self.last_config_path = path
+        self.status_var.set(f"Config gespeichert: {os.path.basename(path)}")
+
+    # -------------------- Refresh / Log --------------------
     def _append_log(self, lines):
         if not lines:
             return
@@ -223,14 +654,135 @@ class DHCPApp(tk.Frame):
         self.log.see("end")
         self.log.configure(state="disabled")
 
+    def _update_leases_view(self, leases: Dict[str, Tuple[str, float]]) -> None:
+        current_items = {self.leases_tree.item(i, "values")[0]: i for i in self.leases_tree.get_children()}
+        # remove stale
+        for mac in set(current_items.keys()) - set(leases.keys()):
+            self.leases_tree.delete(current_items[mac])
+        # add/update
+        now = time.time()
+        for mac, (ip, expiry) in sorted(leases.items()):
+            remaining = max(int(expiry - now), 0)
+            remaining_txt = self._format_duration(remaining)
+            action = "Reserviert" if self._has_reservation(mac) else "Add"
+            if mac in current_items:
+                self.leases_tree.item(current_items[mac], values=(mac, ip, remaining_txt, action))
+            else:
+                self.leases_tree.insert("", "end", values=(mac, ip, remaining_txt, action))
+
     def _refresh(self) -> None:
-        # update clients
-        self.clients.delete(0, "end")
+        leases: Dict[str, Tuple[str, float]] = {}
         if self.server and self.server.is_running():
-            leases = self.server.get_leases()
-            for mac, ip in leases.items():
-                self.clients.insert("end", f"{mac}  →  {ip}")
+            leases = self.server.get_leases_with_expiry()
             self.status_var.set(f"Status: {self.server.get_status()}")
             # pull logs
             self._append_log(self.server.pop_logs(100))
+        else:
+            self.status_var.set("Bereit.")
+
+        self._update_leases_view(leases)
         self.after(400, self._refresh)
+
+    def _refresh_disabled_ext_options(self) -> None:
+        # Update display values for disabled, auto-managed DHCP options
+        dns_list = [d for d in (self.dns1_var.get().strip(), self.dns2_var.get().strip()) if d]
+        dns_text = ", ".join(dns_list)
+        auto_values = {
+            "1": self.mask_var.get().strip(),
+            "3": self.ip_var.get().strip(),
+            "6": dns_text,
+        }
+        for spec in self.ext_option_specs:
+            if not spec.get("disabled"):
+                continue
+            code = spec["code"]
+            if code in auto_values:
+                self.ext_opt_values[code].set(auto_values[code])
+
+    # -------------------- Force Renew --------------------
+    def force_renew_all(self) -> None:
+        if not self.server or not self.server.is_running():
+            messagebox.showinfo("Info", "Server läuft nicht.")
+            return
+
+        ip = self.ip_var.get().strip()
+        mask = self.mask_var.get().strip()
+        try:
+            net = ipaddress.IPv4Network((ip, mask), strict=False)
+        except Exception:
+            messagebox.showerror("Fehler", "Ungültiges Netz (IP/Subnetzmaske) für Force Renew.")
+            return
+        host_count = len(list(net.hosts()))
+        targets = max(host_count - 1, 0)  # exclude server IP roughly
+        extra_warn = ""
+        if targets > 512:
+            extra_warn = f"\nACHTUNG: {targets} Ziele – das kann dauern."
+
+        if not messagebox.askyesno(
+            "Warnung",
+            f"DHCPFORCERENEW wird an alle {targets} IPs im Subnetz {net} gesendet.\n"
+            "Viele Clients ignorieren das, aber es erzeugt Traffic." + extra_warn,
+            icon="warning",
+        ):
+            return
+        try:
+            sent = self.server.force_renew_all()
+            self.status_var.set(f"FORCERENEW gesendet an {sent} Client(s).")
+        except Exception as e:
+            messagebox.showerror("Fehler", str(e))
+
+    # -------------------- Leases actions --------------------
+    def _on_lease_click(self, event) -> None:
+        item_id = self.leases_tree.identify_row(event.y)
+        col = self.leases_tree.identify_column(event.x)
+        if not item_id or col != "#4":  # action column
+            return
+        vals = self.leases_tree.item(item_id, "values")
+        if len(vals) < 4:
+            return
+        mac, ip, action = vals[0], vals[1], vals[3]
+        if action != "Add":
+            return
+        self._add_reservation_from_lease(mac, ip)
+
+    def _add_reservation_from_lease(self, mac: str, ip: str) -> None:
+        if self._has_reservation(mac):
+            messagebox.showinfo("Info", "Reservierung existiert bereits.")
+            return
+        self.res_mac_var.set(mac)
+        self.res_ip_var.set(ip)
+        self.res_name_var.set("")
+        self.add_or_update_reservation()
+
+    # -------------------- Helpers --------------------
+    def _format_duration(self, seconds: int) -> str:
+        if seconds <= 0:
+            return "0s"
+        m, s = divmod(seconds, 60)
+        h, m = divmod(m, 60)
+        if h > 0:
+            return f"{h}h {m}m"
+        if m > 0:
+            return f"{m}m {s}s"
+        return f"{s}s"
+
+    def _ensure_mandatory_ext_options(self, fail_on_missing: bool) -> None:
+        missing = []
+        for spec in self.ext_option_specs:
+            if spec.get("disabled"):
+                continue
+            if not spec.get("mandatory"):
+                continue
+            code = spec["code"]
+            val = self.ext_opt_values[code].get().strip()
+            if not val:
+                default_val = spec.get("default", "")
+                if default_val:
+                    self.ext_opt_values[code].set(default_val)
+                    val = default_val
+            if not val:
+                missing.append(f"Option {code} ({spec.get('label','')})")
+            else:
+                self.ext_opt_enabled[code].set(True)
+        if missing and fail_on_missing:
+            raise ValueError("Folgende Pflicht-Optionen fehlen: " + ", ".join(missing))

src/option_specs.py

@@ -0,0 +1,18 @@
+"""
+Definitions for supported extended DHCP options in the GUI.
+Extend this list to add more options; codes must be numeric strings.
+"""
+
+EXTENDED_OPTION_SPECS = [
+    # Managed internally (anzeige, aber nicht editierbar)
+    {"code": "1", "label": "Subnet Mask", "desc": "Automatisch aus IP-Settings", "type": "text", "disabled": True},
+    {"code": "3", "label": "Router/Gateway", "desc": "Automatisch auf Server-IP", "type": "text", "disabled": True},
+    {"code": "6", "label": "DNS-Server", "desc": "Aus IP-Settings (GUI)", "type": "text", "disabled": True},
+
+    # Freie Optionen (aufsteigend)
+    {"code": "15", "label": "DNS-Suffix", "desc": "DNS-Domäne", "type": "text"},
+    {"code": "42", "label": "NTP-Server", "desc": "NTP-Server IPs (kommagetrennt)", "type": "text"},
+    {"code": "51", "label": "Lease Time", "desc": "Lease in Sekunden (mandatory)", "type": "text", "mandatory": True, "default": "3600"},
+    {"code": "66", "label": "TFTP-Server", "desc": "TFTP-Servername oder IP", "type": "text"},
+    {"code": "67", "label": "Bootfile", "desc": "Bootfile-Name (PXE)", "type": "text"},
+]

src/utils.py

@@ -1,8 +1,11 @@
-import socket
 import ipaddress
-import psutil
+import socket
+import string
 from typing import Optional, Tuple
 
+import psutil
+
+
 def get_network_interfaces():
     """Return only interfaces that have an IPv4 address to keep choices sane."""
     interfaces = []
@@ -21,6 +24,19 @@ def get_iface_ipv4_config(iface: str) -> Tuple[Optional[str], Optional[str]]:
             return a.address, a.netmask
     return None, None
 
+
+def get_iface_hwinfo(iface: str) -> Tuple[Optional[str], Optional[int]]:
+    """Return (MAC, speed_mbps) where available."""
+    mac = None
+    addrs = psutil.net_if_addrs().get(iface, [])
+    for a in addrs:
+        if getattr(a, "family", None) == getattr(psutil, "AF_LINK", None):
+            mac = a.address
+            break
+    stats = psutil.net_if_stats().get(iface)
+    speed = stats.speed if stats else None
+    return mac, speed
+
 def format_ip_address(ip: str) -> str:
     """Normalize dotted quad; raises on invalid input."""
     ip_obj = ipaddress.ip_address(ip)
@@ -31,3 +47,11 @@ def format_ip_address(ip: str) -> str:
 def validate_subnet_mask(mask: str) -> None:
     """Accept masks like 255.255.255.0; raise ValueError if invalid."""
     ipaddress.IPv4Network(f"0.0.0.0/{mask}")
+
+
+def normalize_mac(mac: str) -> str:
+    """Return MAC as AA:BB:CC:DD:EE:FF; raises on invalid input."""
+    cleaned = mac.strip().replace("-", "").replace(":", "").replace(".", "").lower()
+    if len(cleaned) != 12 or any(c not in string.hexdigits for c in cleaned):
+        raise ValueError("Ungültige MAC-Adresse.")
+    return ":".join(cleaned[i:i+2] for i in range(0, 12, 2)).upper()