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