{
  "nftables": [
    {
      "metainfo": {
        "version": "1.0.9",
        "release_name": "Old Doc Yak #3",
        "json_schema_version": 1
      }
    },
    {
      "table": {
        "family": "inet",
        "name": "filter",
        "handle": 1
      }
    },
    {
      "chain": {
        "family": "inet",
        "table": "filter",
        "name": "input",
        "handle": 1,
        "type": "filter",
        "hook": "input",
        "prio": 0,
        "policy": "drop"
      }
    },
    {
      "chain": {
        "family": "inet",
        "table": "filter",
        "name": "forward",
        "handle": 2,
        "type": "filter",
        "hook": "forward",
        "prio": 0,
        "policy": "drop"
      }
    },
    {
      "chain": {
        "family": "inet",
        "table": "filter",
        "name": "output",
        "handle": 3,
        "type": "filter",
        "hook": "output",
        "prio": 0,
        "policy": "accept"
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 4,
        "comment": "early drop of invalid packets",
        "expr": [
          {
            "match": {
              "op": "in",
              "left": {
                "ct": {
                  "key": "state"
                }
              },
              "right": "invalid"
            }
          },
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          },
          {
            "drop": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 6,
        "comment": "accept all connections related to connections made by us",
        "expr": [
          {
            "match": {
              "op": "==",
              "left": {
                "ct": {
                  "key": "state"
                }
              },
              "right": {
                "set": [
                  "established",
                  "related"
                ]
              }
            }
          },
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          },
          {
            "accept": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 7,
        "comment": "accept loopback",
        "expr": [
          {
            "match": {
              "op": "==",
              "left": {
                "meta": {
                  "key": "iif"
                }
              },
              "right": "lo"
            }
          },
          {
            "accept": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 8,
        "comment": "drop connections to loopback not coming from loopback",
        "expr": [
          {
            "match": {
              "op": "!=",
              "left": {
                "meta": {
                  "key": "iif"
                }
              },
              "right": "lo"
            }
          },
          {
            "match": {
              "op": "==",
              "left": {
                "payload": {
                  "protocol": "ip",
                  "field": "daddr"
                }
              },
              "right": {
                "prefix": {
                  "addr": "127.0.0.0",
                  "len": 8
                }
              }
            }
          },
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          },
          {
            "drop": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 9,
        "comment": "drop connections to loopback not coming from loopback",
        "expr": [
          {
            "match": {
              "op": "!=",
              "left": {
                "meta": {
                  "key": "iif"
                }
              },
              "right": "lo"
            }
          },
          {
            "match": {
              "op": "==",
              "left": {
                "payload": {
                  "protocol": "ip6",
                  "field": "daddr"
                }
              },
              "right": "::1"
            }
          },
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          },
          {
            "drop": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 10,
        "comment": "accept all ICMP types",
        "expr": [
          {
            "match": {
              "op": "==",
              "left": {
                "payload": {
                  "protocol": "ip",
                  "field": "protocol"
                }
              },
              "right": "icmp"
            }
          },
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          },
          {
            "accept": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 11,
        "comment": "accept all ICMP types",
        "expr": [
          {
            "match": {
              "op": "==",
              "left": {
                "payload": {
                  "protocol": "ip6",
                  "field": "nexthdr"
                }
              },
              "right": "ipv6-icmp"
            }
          },
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          },
          {
            "accept": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 12,
        "comment": "accept SSH",
        "expr": [
          {
            "match": {
              "op": "==",
              "left": {
                "payload": {
                  "protocol": "tcp",
                  "field": "dport"
                }
              },
              "right": 22
            }
          },
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          },
          {
            "accept": null
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "input",
        "handle": 13,
        "comment": "count dropped packets",
        "expr": [
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "forward",
        "handle": 14,
        "comment": "count dropped packets",
        "expr": [
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          }
        ]
      }
    },
    {
      "rule": {
        "family": "inet",
        "table": "filter",
        "chain": "output",
        "handle": 15,
        "comment": "count accepted packets",
        "expr": [
          {
            "counter": {
              "packets": 0,
              "bytes": 0
            }
          }
        ]
      }
    }
  ]
}