docs: update readme and add development

Author: umegbewe

DEVELOPMENT.md

@@ -0,0 +1,111 @@
+# Development
+
+This doc will guide you through testing ``dhcpd`` safely without impacting your main network. Deploying a DHCP server on your main network can cause conflicts with existing DHCP services (like the one provided by your router). 
+
+We'll set up an isolated test environment using linux network namespaces and virtual Ethernet interfaces.
+
+
+## Guide
+
+create network namespaces for client and server
+
+```bash
+sudo ip netns add server_ns
+sudo ip netns add client_ns
+```
+
+create virtual ethernet pair to connect server and client namespace
+
+```bash
+sudo ip link add veth-server type veth peer name veth-client
+```
+
+assign interfaces to namespaces
+```bash
+sudo ip link set veth-server netns server_ns
+sudo ip link set veth-client netns client_ns
+```
+
+configure server namespace
+
+```bash
+sudo ip netns exec server_ns ip addr add 192.168.100.1/24 dev veth-server
+sudo ip netns exec server_ns ip link set dev veth-server up
+sudo ip netns exec server_ns ip link set dev lo up
+sudo ip netns exec server_ns ip route add 255.255.255.255 dev veth-server
+
+```
+
+
+configure client namespace
+```bash 
+sudo ip netns exec client_ns ip link set dev veth-client up
+sudo ip netns exec client_ns ip link set dev lo up
+```
+
+update config to listen on ``veth server``
+
+conf.yaml:
+```yaml
+server:
+  ip_start: 192.168.100.10
+  ip_end: 192.168.100.255
+  subnet_mask: 255.255.255.0
+  lease_time: 600
+  gateway: 192.168.1.10
+  server_ip: 192.168.1.10
+  port: 67
+  dns_servers:
+    - 8.8.8.8
+    - 8.8.4.4
+  interface: en0
+  lease_db_path: leases.db
+  cleanup_expired_interval: 120
+logging:
+  level: info
+metrics:
+  enabled: true
+  listen_address: '0.0.0.0:9100' 
+```
+
+run dhcpd in server namespace
+
+```bash
+sudo ip netns exec server_ns ./dhcpd
+```
+ensure it's running and listening on ``veth-server``, you should see an output similar to this:
+
+```
+INFO[2025-01-03T10:07:47+01:00] [INIT] Set to cleanup expired leases every 120 seconds 
+INFO[2025-01-03T10:07:47+01:00] [INIT] Metrics server listening on :9100     
+INFO[2025-01-03T10:07:47+01:00] [INIT] DHCP server listening on 0.0.0.0:67 (interface: veth-server, IP: 192.168.100.10)
+```
+
+
+run dhcp client in client namespace
+
+```bash
+sudo ip netns exec client_ns dhclient -v veth-client
+```
+
+verify ip assignment 
+```bash
+sudo ip netns exec client_ns ip addr show dev veth-client
+```
+
+you should see an IP assigned within the range specified in ``conf.yaml``
+
+```bash
+3: veth-client@if4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP 
+    link/ether ba:ad:c0:ff:ee:01 brd ff:ff:ff:ff:ff:ff
+    inet 192.168.100.10/24 brd 192.168.100.255 scope global dynamic veth-client
+       valid_lft 86396sec preferred_lft 86396sec
+```
+
+cleanup
+
+```bash
+sudo ip netns del server_ns
+sudo ip netns del client_ns
+sudo ip link delete veth-server
+```

README.md

@@ -58,7 +58,6 @@ bound to 192.168.100.92 -- renewal in 261 seconds.
 `dhcpd` also provides server and lease metrics, accessible at `:9100/metrics`. Additionally, a sample Grafana dashboard [JSON](https://github.com/umegbewe/dhcpd/blob/699c7546e35768876f2b3d40d43bfb46b5d5f612/grafana/%20dashboard.json) is available for visualizing these metrics."
 
 
-
 <img src="https://github.com/umegbewe/dhcpd/blob/main/grafana/screenshot.png">
 
 ## Future work