add nmap service

configuration.nix

@@ -102,4 +102,46 @@
 
   system.stateVersion = "25.05";
 
+  systemd.timers."scan" = {
+    wantedBy = [ "timers.target" ];
+      timerConfig = {
+        OnBootSec = "5m";
+        OnCalendar = "*:0/5";
+        Unit = "scan.service";
+      };
+  };
+
+  systemd.services."scan" = {
+    script = ''
+      /run/current-system/sw/bin/nmap -sn 192.168.1.0/24 \
+      | /run/current-system/sw/bin/awk '
+      /Nmap scan report for/ {
+          if (match($0, /\(([^)]+)\)/)) {
+              ip = substr($0, RSTART+1, RLENGTH-2)
+              host = $5
+          } else {
+              ip = $NF
+              host = ""
+          }
+      }
+      /MAC Address:/ {
+          mac = $3
+          vendor = $0
+          sub(/^.*\(/, "", vendor)
+          sub(/\).*$/, "", vendor)
+
+          print ip "," host "," vendor "," mac
+      }
+      ' > "/data/nmap/$(date +%F_%H-%M-%S)-nmap.csv"
+    '';
+    serviceConfig = {
+      Type = "oneshot";
+      User = "root";
+    };
+  };
+  
+  systemd.tmpfiles.rules = [
+    "d /data 777 root root"
+    "d /data/nmap 777 root root"
+  ];
 }