reaction/config/reaction.yml

---
# TODO heavily comment this file
# definitions are just a place to put chunks of conf you want to reuse in another place
# they're not readed by reaction
definitions:
  - &iptablesban [ "iptables" "-w" "-A" "reaction" "1" "-s" "<ip>" "-j" "DROP" ]
  - &iptablesunban [ "iptables" "-w" "-D" "reaction" "1" "-s" "<ip>" "-j" "DROP" ]

# patterns are substitued in regexes.
# when a filter performs an action, it replaces the found pattern
patterns:
  ip: '(([0-9]{1,3}\.){3}[0-9]{1,3})|([0-9a-fA-F:]{2,90})'

# streams are command that are run
# their output will be used by one or more filters
streams:
  # streams have a user-defined name
  ssh:
    # note that if the command is not in environment's `PATH`
    # its full path must be given.
    cmd: [ "journalctl" "-fu" "sshd.service" ]
    # filters are a set of regexes on a stream
    # when a regex matches, it will trigger the filter's actions
    filters:
      # filters have a user-defined name
      failedlogin:
        regex:
          - authentication failure;.*rhost=<ip>
        # if retry and retry-period are defined,
        # the actions will only take place if a same pattern is
        # found `retry` times in a `retry-period` interval
        retry: 3
        # format is defined here: https://pkg.go.dev/time#ParseDuration
        retry-period: 6h
        actions:
          # actions have a user-defined name
          ban:
            # YAML substitutes *reference by the value at &reference
            cmd: *iptablesban
          unban:
            cmd:  *iptablesunban
            # if after is defined, the action will not take place immediately, but after a specified duration.
            # same format as retry-period
            after: 2d