scripts/scan.awk: add script to scan IPv6 link local

scripts/scan.awk

@@ -0,0 +1,29 @@
+BEGIN {
+  "nix build -f '<nixpkgs>' nmap --no-link --json | jq -r '.[0].outputs.out'"|getline nmap
+  db = nmap"/share/nmap/nmap-mac-prefixes"
+  while((getline line < db) > 0)
+    {
+      n = split(line, rec, " ");
+      prefix = rec[1]
+      vendors[prefix] = rec[2]
+      for (i=3; i<n; i++)
+        vendors[prefix] = vendors[prefix]" "rec[i]
+    }
+  FS=" |%"
+}
+
+/ff:fe/ {
+  eui64 = $4
+  eui48 = eui64
+  gsub(/ff:fe|fe80::/, "", eui48)
+  gsub(":", "", eui48)
+  mac = xor(strtonum("0x"eui48), lshift(1, 41))
+  prefix = substr(sprintf("%X", mac), 0, 6)
+  mac = sprintf("%012x", mac)
+  prettymac = ""
+  for (i=0; i<=6; i++)
+  { prettymac = prettymac substr(mac,2*i+1,2)
+    if (i < 5) prettymac = prettymac":"
+  }
+  printf("%25s\t%s\t%s\n", eui64, prettymac, vendors[prefix])
+}