feat: basic firewall config to test it out

applications/firewall.nix

@@ -0,0 +1,51 @@
+{
+
+  networking.nftables.enable = true;
+
+  # fules for the
+  networking.nftables.ruleset = ''
+    # Check out https://wiki.nftables.org/ for better documentation.
+    # Table for both IPv4 and IPv6.
+    table inet filter {
+      # Block all incomming connections traffic except SSH and "ping".
+      chain input {
+        type filter hook input priority 0;
+
+        # accept any localhost traffic
+        iifname lo accept
+
+        # accept traffic originated from us
+        ct state {established, related} accept
+
+        # ICMP
+        # routers may also want: mld-listener-query, nd-router-solicit
+        ip6 nexthdr icmpv6 icmpv6 type { destination-unreachable, packet-too-big, time-exceeded, parameter-problem, nd-router-advert, nd-neighbor-solicit, nd-neighbor-advert } accept
+        ip protocol icmp icmp type { destination-unreachable, router-advertisement, time-exceeded, parameter-problem } accept
+
+        # allow "ping"
+        ip6 nexthdr icmpv6 icmpv6 type echo-request accept
+        ip protocol icmp icmp type echo-request accept
+
+        # accept SSH connections (required for a server)
+        tcp dport 22 accept
+        # tcp dport 21 accept
+
+        # count and drop any other traffic
+        counter drop
+      }
+
+      # Allow all outgoing connections.
+      chain output {
+        type filter hook output priority 0;
+        accept
+      }
+
+      chain forward {
+        type filter hook forward priority 0;
+        accept
+      }
+    }
+  '';
+
+
+}