Added DHCP server tutorial

Author: ClemensElflein

content/en/docs/Tutorials/installing-dhcp-server/_index.md

@@ -0,0 +1,159 @@
+---
+title: "Installing and Configuring a DHCP Server"
+linkTitle: "Install a DHCP Server"
+description: This guide walks you through setting up `isc-dhcp-server` on your xCore board.
+---
+
+## Why Set Up a DHCP Server?
+
+The xCore board serves as the central hub in an internal network used by your robot.
+The xCore includes a microcontroller (STM32) which talks directly with the Linux system. To enable this, we create a private network on `eth0` with a static IP and assign dynamic IPs to connected devices using DHCP.
+The STM32 will acquire an IP address automatically.
+
+
+---
+
+## Step 1: Set Static IP on `eth0`
+
+We will assign a static IP `172.16.78.1` to `eth0`. You can do this using the built-in network configuration utility:
+
+```bash
+sudo nmtui
+```
+
+1. Select **Edit a connection**
+2. Choose your **Wired connection**
+3. Set **IPv4 Configuration** to **Manual**
+4. Add:
+    - Address: `172.16.78.1`
+    - Netmask: `255.255.255.0`
+    - Gateway: leave blank
+5. Save and **Activate** the connection
+
+> 💡 You may also use `nmcli` instead:
+```bash
+sudo nmcli con mod "Wired connection 1" ipv4.method manual ipv4.addresses 172.16.78.1/24
+sudo nmcli con up "Wired connection 1"
+```
+
+Verify the result by running `ip -4 address show dev eth0`.
+The expected output should be:
+```bash
+robot@robot:~ $ ip -4 address show dev eth0
+2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
+    inet 172.16.78.1/24 brd 172.16.78.255 scope global noprefixroute eth0
+       valid_lft forever preferred_lft forever
+```
+
+---
+
+## Step 2: Install the DHCP Server
+
+```bash
+sudo apt-get update
+sudo apt-get install isc-dhcp-server -y
+```
+
+---
+
+## Step 3: Configure DHCP Server
+
+### Edit default interface
+
+Open `/etc/default/isc-dhcp-server`:
+
+```bash
+sudo nano /etc/default/isc-dhcp-server
+```
+
+Find and modify this line:
+
+```bash
+INTERFACESv4="eth0"
+```
+
+Save the configuration by pressing `CTRL+O`, `ENTER`. Then exit nano by pressing `CTRL+X`.
+
+---
+
+### Add DHCP configuration
+
+Edit the main DHCP config file:
+
+```bash
+sudo nano /etc/dhcp/dhcpd.conf
+```
+
+Replace the config with the following:
+
+```conf
+default-lease-time 600;
+max-lease-time 7200;
+authoritative;
+
+subnet 172.16.78.0 netmask 255.255.255.0 {
+  interface eth0;
+  range 172.16.78.150 172.16.78.200;
+  option routers 172.16.78.1;
+  option domain-name-servers 172.16.78.1;
+  option domain-name "robot.local";
+}
+```
+
+---
+
+## Step 4: Start the DHCP Server
+
+```bash
+sudo systemctl start isc-dhcp-server
+```
+
+Enable it at boot:
+
+```bash
+sudo systemctl enable isc-dhcp-server
+```
+
+---
+
+## Verification
+
+Run:
+
+```bash
+sudo systemctl status isc-dhcp-server
+```
+
+Make sure the output includes `active (running)`.
+
+Try to ping your STM32:
+Get the assigned IP by running `cat /var/lib/dhcp/dhcpd.leases`
+
+**Example output:**
+```bash
+robot@robot:~ $ cat /var/lib/dhcp/dhcpd.leases
+# The format of this file is documented in the dhcpd.leases(5) manual page.
+# This lease file was written by isc-dhcp-4.4.3-P1
+
+# authoring-byte-order entry is generated, DO NOT DELETE
+authoring-byte-order little-endian;
+
+server-duid "\000\001\000\001/\244\342\375,\317gJ\305\345";
+
+lease 172.16.78.150 {
+  starts 3 2025/04/30 13:33:05;
+  ends 3 2025/04/30 13:43:05;
+  cltt 3 2025/04/30 13:33:05;
+  binding state active;
+  next binding state free;
+  rewind binding state free;
+  hardware ethernet d8:47:8f:91:b9:6c;
+}
+```
+
+Then you should be able to ping the STM32:
+```bash
+robot@robot:~ $ ping 172.16.78.150
+PING 172.16.78.150 (172.16.78.150) 56(84) bytes of data.
+64 bytes from 172.16.78.150: icmp_seq=1 ttl=255 time=0.354 ms
+```