fail2ban

#!/bin/bash

# Create a dedicated fail2ban config (jail and filter conf files)
#
# usage 1: ynh_add_fail2ban_config --logpath=log_file --failregex=filter [--max_retry=max_retry] [--ports=ports]
# | arg: -l, --logpath=   - Log file to be checked by fail2ban
# | arg: -r, --failregex= - Failregex to be looked for by fail2ban
# | arg: -m, --max_retry= - Maximum number of retries allowed before banning IP address - default: 3
# | arg: -p, --ports=     - Ports blocked for a banned IP address - default: http,https
#
# -----------------------------------------------------------------------------
#
# usage 2: ynh_add_fail2ban_config --use_template [--others_var="list of others variables to replace"]
# | arg: -t, --use_template - Use this helper in template mode
# | arg: -v, --others_var=  - List of others variables to replace separeted by a space
# |                           for example : 'var_1 var_2 ...'
#
# This will use a template in ../conf/f2b_jail.conf and ../conf/f2b_filter.conf
#   __APP__      by  $app
#
#  You can dynamically replace others variables by example :
#   __VAR_1__    by $var_1
#   __VAR_2__    by $var_2
#
# Generally your template will look like that by example (for synapse):
#
# f2b_jail.conf:
#     [__APP__]
#     enabled = true
#     port = http,https
#     filter = __APP__
#     logpath = /var/log/__APP__/logfile.log
#     maxretry = 3
#
# f2b_filter.conf:
#     [INCLUDES]
#     before = common.conf
#     [Definition]
#
#     # Part of regex definition (just used to make more easy to make the global regex)
#     __synapse_start_line = .? \- synapse\..+ \-
#
#    # Regex definition.
#    failregex = ^%(__synapse_start_line)s INFO \- POST\-(\d+)\- <HOST> \- \d+ \- Received request\: POST /_matrix/client/r0/login\??<SKIPLINES>%(__synapse_start_line)s INFO \- POST\-\1\- Got login request with identifier: \{u'type': u'm.id.user', u'user'\: u'(.+?)'\}, medium\: None, address: None, user\: u'\5'<SKIPLINES>%(__synapse_start_line)s WARNING \- \- (Attempted to login as @\5\:.+ but they do not exist|Failed password login for user @\5\:.+)$
#
#     ignoreregex =
#
# -----------------------------------------------------------------------------
#
# Note about the "failregex" option:
#          regex to match the password failure messages in the logfile. The
#          host must be matched by a group named "host". The tag "<HOST>" can
#          be used for standard IP/hostname matching and is only an alias for
#          (?:::f{4,6}:)?(?P<host>[\w\-.^_]+)
#
#          You can find some more explainations about how to make a regex here :
#          https://www.fail2ban.org/wiki/index.php/MANUAL_0_8#Filters
#
# Note that the logfile need to exist before to call this helper !!
#
# To validate your regex you can test with this command:
# fail2ban-regex /var/log/YOUR_LOG_FILE_PATH /etc/fail2ban/filter.d/YOUR_APP.conf
#
# Requires YunoHost version 3.5.0 or higher.
ynh_add_fail2ban_config () {
    # Declare an array to define the options of this helper.
    local legacy_args=lrmptv
    local -A args_array=( [l]=logpath= [r]=failregex= [m]=max_retry= [p]=ports= [t]=use_template [v]=others_var=)
    local logpath
    local failregex
    local max_retry
    local ports
    local others_var
    local use_template
    # Manage arguments with getopts
    ynh_handle_getopts_args "$@"
    max_retry=${max_retry:-3}
    ports=${ports:-http,https}
    others_var=${others_var:-}
    use_template="${use_template:-0}"

    finalfail2banjailconf="/etc/fail2ban/jail.d/$app.conf"
    finalfail2banfilterconf="/etc/fail2ban/filter.d/$app.conf"
    ynh_backup_if_checksum_is_different "$finalfail2banjailconf"
    ynh_backup_if_checksum_is_different "$finalfail2banfilterconf"

    if [ $use_template -eq 1 ]
    then
        # Usage 2, templates
        cp ../conf/f2b_jail.conf $finalfail2banjailconf
        cp ../conf/f2b_filter.conf $finalfail2banfilterconf

        if [ -n "${app:-}" ]
        then
            ynh_replace_string "__APP__" "$app" "$finalfail2banjailconf"
            ynh_replace_string "__APP__" "$app" "$finalfail2banfilterconf"
        fi

        # Replace all other variable given as arguments
        for var_to_replace in $others_var
        do
            # ${var_to_replace^^} make the content of the variable on upper-cases
            # ${!var_to_replace} get the content of the variable named $var_to_replace
            ynh_replace_string --match_string="__${var_to_replace^^}__" --replace_string="${!var_to_replace}" --target_file="$finalfail2banjailconf"
            ynh_replace_string --match_string="__${var_to_replace^^}__" --replace_string="${!var_to_replace}" --target_file="$finalfail2banfilterconf"
        done

    else
        # Usage 1, no template. Build a config file from scratch.
        test -n "$logpath" || ynh_die "ynh_add_fail2ban_config expects a logfile path as first argument and received nothing."
        test -n "$failregex" || ynh_die "ynh_add_fail2ban_config expects a failure regex as second argument and received nothing."

        tee $finalfail2banjailconf <<EOF
[$app]
enabled = true
port = $ports
filter = $app
logpath = $logpath
maxretry = $max_retry
EOF

    tee $finalfail2banfilterconf <<EOF
[INCLUDES]
before = common.conf
[Definition]
failregex = $failregex
ignoreregex =
EOF
    fi

    # Common to usage 1 and 2.
    ynh_store_file_checksum "$finalfail2banjailconf"
    ynh_store_file_checksum "$finalfail2banfilterconf"

    ynh_systemd_action --service_name=fail2ban --action=reload --line_match="(Started|Reloaded) Fail2Ban Service" --log_path=systemd

    local fail2ban_error="$(journalctl --no-hostname --unit=fail2ban | tail --lines=50 | grep "WARNING.*$app.*")"
    if [[ -n "$fail2ban_error" ]]
    then
        ynh_print_err --message="Fail2ban failed to load the jail for $app"
        ynh_print_warn --message="${fail2ban_error#*WARNING}"
    fi
}

# Remove the dedicated fail2ban config (jail and filter conf files)
#
# usage: ynh_remove_fail2ban_config
#
# Requires YunoHost version 3.5.0 or higher.
ynh_remove_fail2ban_config () {
    ynh_secure_remove "/etc/fail2ban/jail.d/$app.conf"
    ynh_secure_remove "/etc/fail2ban/filter.d/$app.conf"
    ynh_systemd_action --service_name=fail2ban --action=reload
}