forked from mirrors/nixpkgs
afb6fe2fff
some ban actions need additional packages (eg ipset). since actions can be provided by the user we need something general that's easy to configure. we could also enable ipset regardless of the actual configuration of the system if the iptables firewall is in use (like sshguard does), but that seems very clumsy and wouldn't easily solve the binary-not-found problems other actions may also have.
323 lines
11 KiB
Nix
323 lines
11 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.services.fail2ban;
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fail2banConf = pkgs.writeText "fail2ban.local" cfg.daemonConfig;
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jailConf = pkgs.writeText "jail.local" ''
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[INCLUDES]
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before = paths-nixos.conf
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${concatStringsSep "\n" (attrValues (flip mapAttrs cfg.jails (name: def:
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optionalString (def != "")
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''
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[${name}]
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${def}
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'')))}
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'';
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pathsConf = pkgs.writeText "paths-nixos.conf" ''
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# NixOS
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[INCLUDES]
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before = paths-common.conf
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after = paths-overrides.local
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[DEFAULT]
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'';
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in
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{
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###### interface
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options = {
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services.fail2ban = {
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enable = mkOption {
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default = false;
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type = types.bool;
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description = "Whether to enable the fail2ban service.";
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};
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package = mkOption {
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default = pkgs.fail2ban;
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type = types.package;
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example = "pkgs.fail2ban_0_11";
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description = "The fail2ban package to use for running the fail2ban service.";
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};
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packageFirewall = mkOption {
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default = pkgs.iptables;
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type = types.package;
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example = "pkgs.nftables";
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description = "The firewall package used by fail2ban service.";
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};
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extraPackages = mkOption {
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default = [];
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type = types.listOf types.package;
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example = lib.literalExample "[ pkgs.ipset ]";
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description = ''
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Extra packages to be made available to the fail2ban service. The example contains
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the packages needed by the `iptables-ipset-proto6` action.
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'';
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};
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maxretry = mkOption {
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default = 3;
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type = types.ints.unsigned;
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description = "Number of failures before a host gets banned.";
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};
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banaction = mkOption {
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default = "iptables-multiport";
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type = types.str;
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example = "nftables-multiport";
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description = ''
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Default banning action (e.g. iptables, iptables-new, iptables-multiport,
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shorewall, etc) It is used to define action_* variables. Can be overridden
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globally or per section within jail.local file
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'';
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};
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banaction-allports = mkOption {
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default = "iptables-allport";
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type = types.str;
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example = "nftables-allport";
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description = ''
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Default banning action (e.g. iptables, iptables-new, iptables-multiport,
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shorewall, etc) It is used to define action_* variables. Can be overridden
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globally or per section within jail.local file
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'';
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};
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bantime-increment.enable = mkOption {
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default = false;
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type = types.bool;
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description = ''
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Allows to use database for searching of previously banned ip's to increase
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a default ban time using special formula, default it is banTime * 1, 2, 4, 8, 16, 32...
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'';
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};
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bantime-increment.rndtime = mkOption {
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default = "4m";
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type = types.str;
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example = "8m";
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description = ''
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"bantime-increment.rndtime" is the max number of seconds using for mixing with random time
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to prevent "clever" botnets calculate exact time IP can be unbanned again
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'';
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};
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bantime-increment.maxtime = mkOption {
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default = "10h";
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type = types.str;
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example = "48h";
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description = ''
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"bantime-increment.maxtime" is the max number of seconds using the ban time can reach (don't grows further)
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'';
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};
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bantime-increment.factor = mkOption {
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default = "1";
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type = types.str;
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example = "4";
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description = ''
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"bantime-increment.factor" is a coefficient to calculate exponent growing of the formula or common multiplier,
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default value of factor is 1 and with default value of formula, the ban time grows by 1, 2, 4, 8, 16 ...
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'';
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};
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bantime-increment.formula = mkOption {
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default = "ban.Time * (1<<(ban.Count if ban.Count<20 else 20)) * banFactor";
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type = types.str;
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example = "ban.Time * math.exp(float(ban.Count+1)*banFactor)/math.exp(1*banFactor)";
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description = ''
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"bantime-increment.formula" used by default to calculate next value of ban time, default value bellow,
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the same ban time growing will be reached by multipliers 1, 2, 4, 8, 16, 32...
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'';
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};
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bantime-increment.multipliers = mkOption {
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default = "1 2 4 8 16 32 64";
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type = types.str;
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example = "2 4 16 128";
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description = ''
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"bantime-increment.multipliers" used to calculate next value of ban time instead of formula, coresponding
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previously ban count and given "bantime.factor" (for multipliers default is 1);
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following example grows ban time by 1, 2, 4, 8, 16 ... and if last ban count greater as multipliers count,
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always used last multiplier (64 in example), for factor '1' and original ban time 600 - 10.6 hours
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'';
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};
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bantime-increment.overalljails = mkOption {
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default = false;
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type = types.bool;
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example = true;
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description = ''
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"bantime-increment.overalljails" (if true) specifies the search of IP in the database will be executed
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cross over all jails, if false (dafault), only current jail of the ban IP will be searched
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'';
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};
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ignoreIP = mkOption {
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default = [ ];
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type = types.listOf types.str;
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example = [ "192.168.0.0/16" "2001:DB8::42" ];
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description = ''
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"ignoreIP" can be a list of IP addresses, CIDR masks or DNS hosts. Fail2ban will not ban a host which
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matches an address in this list. Several addresses can be defined using space (and/or comma) separator.
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'';
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};
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daemonConfig = mkOption {
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default = ''
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[Definition]
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logtarget = SYSLOG
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socket = /run/fail2ban/fail2ban.sock
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pidfile = /run/fail2ban/fail2ban.pid
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dbfile = /var/lib/fail2ban/fail2ban.sqlite3
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'';
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type = types.lines;
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description = ''
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The contents of Fail2ban's main configuration file. It's
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generally not necessary to change it.
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'';
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};
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jails = mkOption {
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default = { };
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example = literalExample ''
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{ apache-nohome-iptables = '''
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# Block an IP address if it accesses a non-existent
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# home directory more than 5 times in 10 minutes,
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# since that indicates that it's scanning.
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filter = apache-nohome
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action = iptables-multiport[name=HTTP, port="http,https"]
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logpath = /var/log/httpd/error_log*
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findtime = 600
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bantime = 600
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maxretry = 5
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''';
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}
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'';
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type = types.attrsOf types.lines;
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description = ''
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The configuration of each Fail2ban “jail”. A jail
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consists of an action (such as blocking a port using
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<command>iptables</command>) that is triggered when a
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filter applied to a log file triggers more than a certain
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number of times in a certain time period. Actions are
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defined in <filename>/etc/fail2ban/action.d</filename>,
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while filters are defined in
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<filename>/etc/fail2ban/filter.d</filename>.
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'';
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};
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};
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};
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###### implementation
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config = mkIf cfg.enable {
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warnings = mkIf (config.networking.firewall.enable == false && config.networking.nftables.enable == false) [
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"fail2ban can not be used without a firewall"
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];
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environment.systemPackages = [ cfg.package ];
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environment.etc = {
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"fail2ban/fail2ban.local".source = fail2banConf;
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"fail2ban/jail.local".source = jailConf;
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"fail2ban/fail2ban.conf".source = "${cfg.package}/etc/fail2ban/fail2ban.conf";
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"fail2ban/jail.conf".source = "${cfg.package}/etc/fail2ban/jail.conf";
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"fail2ban/paths-common.conf".source = "${cfg.package}/etc/fail2ban/paths-common.conf";
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"fail2ban/paths-nixos.conf".source = pathsConf;
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"fail2ban/action.d".source = "${cfg.package}/etc/fail2ban/action.d/*.conf";
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"fail2ban/filter.d".source = "${cfg.package}/etc/fail2ban/filter.d/*.conf";
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};
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systemd.services.fail2ban = {
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description = "Fail2ban Intrusion Prevention System";
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wantedBy = [ "multi-user.target" ];
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after = [ "network.target" ];
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partOf = optional config.networking.firewall.enable "firewall.service";
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restartTriggers = [ fail2banConf jailConf pathsConf ];
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reloadIfChanged = true;
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path = [ cfg.package cfg.packageFirewall pkgs.iproute2 ] ++ cfg.extraPackages;
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unitConfig.Documentation = "man:fail2ban(1)";
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serviceConfig = {
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ExecStart = "${cfg.package}/bin/fail2ban-server -xf start";
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ExecStop = "${cfg.package}/bin/fail2ban-server stop";
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ExecReload = "${cfg.package}/bin/fail2ban-server reload";
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Type = "simple";
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Restart = "on-failure";
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PIDFile = "/run/fail2ban/fail2ban.pid";
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# Capabilities
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CapabilityBoundingSet = [ "CAP_AUDIT_READ" "CAP_DAC_READ_SEARCH" "CAP_NET_ADMIN" "CAP_NET_RAW" ];
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# Security
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NoNewPrivileges = true;
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# Directory
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RuntimeDirectory = "fail2ban";
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RuntimeDirectoryMode = "0750";
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StateDirectory = "fail2ban";
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StateDirectoryMode = "0750";
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LogsDirectory = "fail2ban";
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LogsDirectoryMode = "0750";
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# Sandboxing
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ProtectSystem = "strict";
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ProtectHome = true;
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PrivateTmp = true;
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PrivateDevices = true;
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ProtectHostname = true;
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ProtectKernelTunables = true;
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ProtectKernelModules = true;
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ProtectControlGroups = true;
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};
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};
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# Add some reasonable default jails. The special "DEFAULT" jail
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# sets default values for all other jails.
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services.fail2ban.jails.DEFAULT = ''
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${optionalString cfg.bantime-increment.enable ''
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# Bantime incremental
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bantime.increment = ${boolToString cfg.bantime-increment.enable}
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bantime.maxtime = ${cfg.bantime-increment.maxtime}
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bantime.factor = ${cfg.bantime-increment.factor}
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bantime.formula = ${cfg.bantime-increment.formula}
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bantime.multipliers = ${cfg.bantime-increment.multipliers}
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bantime.overalljails = ${boolToString cfg.bantime-increment.overalljails}
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''}
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# Miscellaneous options
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ignoreip = 127.0.0.1/8 ${optionalString config.networking.enableIPv6 "::1"} ${concatStringsSep " " cfg.ignoreIP}
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maxretry = ${toString cfg.maxretry}
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backend = systemd
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# Actions
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banaction = ${cfg.banaction}
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banaction_allports = ${cfg.banaction-allports}
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'';
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# Block SSH if there are too many failing connection attempts.
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services.fail2ban.jails.sshd = mkDefault ''
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enabled = true
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port = ${concatMapStringsSep "," (p: toString p) config.services.openssh.ports}
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'';
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};
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}
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