155 lines
4.2 KiB
Nix
155 lines
4.2 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.conf" cfg.daemonConfig;
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jailConf = pkgs.writeText "jail.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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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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daemonConfig = mkOption {
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default =
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''
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[Definition]
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loglevel = INFO
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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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'';
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type = types.lines;
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description =
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''
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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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''
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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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environment.systemPackages = [ pkgs.fail2ban ];
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environment.etc."fail2ban/fail2ban.conf".source = fail2banConf;
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environment.etc."fail2ban/jail.conf".source = jailConf;
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environment.etc."fail2ban/action.d".source = "${pkgs.fail2ban}/etc/fail2ban/action.d/*.conf";
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environment.etc."fail2ban/filter.d".source = "${pkgs.fail2ban}/etc/fail2ban/filter.d/*.conf";
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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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restartTriggers = [ fail2banConf jailConf ];
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path = [ pkgs.fail2ban pkgs.iptables ];
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preStart =
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''
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mkdir -p /run/fail2ban -m 0755
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mkdir -p /var/lib/fail2ban
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'';
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serviceConfig =
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{ ExecStart = "${pkgs.fail2ban}/bin/fail2ban-server -f";
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ReadOnlyDirectories = "/";
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ReadWriteDirectories = "/run /var/tmp /var/lib";
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CapabilityBoundingSet = "CAP_DAC_READ_SEARCH CAP_NET_ADMIN CAP_NET_RAW";
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};
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postStart =
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''
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# Wait for the server to start listening.
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for ((n = 0; n < 20; n++)); do
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if fail2ban-client ping; then break; fi
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sleep 0.5
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done
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# Reload its configuration.
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fail2ban-client reload
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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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''
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ignoreip = 127.0.0.1/8
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bantime = 600
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findtime = 600
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maxretry = 3
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backend = systemd
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enabled = true
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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.ssh-iptables =
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''
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filter = sshd
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action = iptables[name=SSH, port=ssh, protocol=tcp]
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maxretry = 5
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'';
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};
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}
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