NetIRC Defender V3

Modular IRC security service for P10 (ircu-style) uplinks: DNSBL checks, flood controls, G-lines, channel enforcement, optional GeoIP (ipinfo), console whois / seen from the link cache (including away when the hub reports it on the link), and more. Written in Perl.

Lineage: the codebase shares roots with the public key2peace/defender project (Defender IRC service). You do not need a GitHub “Fork” of that repo to publish this tree: a standalone repository is fine. NetIRC Defender V3 is this project’s name and P10-focused evolution. Keep the GPL-2.0 license file and existing copyright headers in source files when you redistribute (see License).

Requirements

• Perl 5.10+. Networking uses Socket and IO::Socket, which ship with a normal Perl build as core modules (they are not separate CPAN installs when you use the perl package from your Linux distribution).
• Linux (or similar) is assumed for production; P10 link to your hub.
• Config parsing: this tree bundles Config::General and Tie::IxHash under Config/ and Tie/ — you do not install those from CPAN.
• dnsbl module: uses the same core Socket helpers (gethostbyname / inet_ntoa) for RBL DNS lookups — no Net::DNS or other CPAN DNS stack. Lists and replies are read from dnsbl.conf in your datadir. Use dnsbl.conf.example in the repository as a template (copy to datadir/dnsbl.conf and replace with zones you are allowed to query).

New server: install Perl (VPS / bare metal)

Install the perl (and on some distros perl-modules) package from your distribution; you do not need to compile Perl from source.

Socket / IO::Socket: these are part of perl-core. A stock apt install perl or dnf install perl pulls them in, so you do not run cpan / cpanm for the IRC uplink, dnsbl RBL checks, or other DNS-style lookups in this codebase.

Extra CPAN: not required for this tree — config helpers and related code are bundled.

Debian / Ubuntu

sudo apt update
sudo apt install -y perl perl-modules openssl ca-certificates
perl -v   # confirm 5.10 or newer

Rocky Linux / AlmaLinux / Fedora / RHEL

sudo dnf install -y perl perl-IO-Socket-SSL openssl
perl -v

Then continue with Quick start (clone, defender.conf, run).

Quick start

1. Clone the repository.

2. Copy the sample config next to defender.pl and edit it (defender.conf is always loaded from that directory, not from datadir):

   cp defender.conf.example defender.conf
   $EDITOR defender.conf

   If you add the version module to modules=, add rules in datadir/deny_version.conf (see datadir in defender.conf; it is often your clone/install directory):

   cp deny_version.conf.example /path/to/your/deny_version.conf
   $EDITOR /path/to/your/deny_version.conf

   If dnsbl is in modules=, create datadir/dnsbl.conf (Config::General; one block per RBL zone). You can start from the template:

   cp dnsbl.conf.example /path/to/your/dnsbl.conf
   $EDITOR /path/to/your/dnsbl.conf

   Optional — regexp_akill: not enabled in the default modules= list in defender.conf.example. If you add regexp_akill to modules=, create datadir/regexp_akill.conf (the module logs if the file is missing). Template:

   cp regexp_akill.conf.example /path/to/your/regexp_akill.conf
   $EDITOR /path/to/your/regexp_akill.conf

3. Run (foreground debug):

   perl defender.pl --debug

   Or daemon mode (default when not passing --debug), per defender.pl / Modules/Main.pm.

Service control (manual)

Use defender.sh for normal operator actions (same directory as defender.pl):

chmod +x defender.sh
./defender.sh start    # daemon via defender.pl
./defender.sh stop     # SIGINT, then SIGKILL if needed
./defender.sh restart
./defender.sh status

Watchdog (automatic, cron only)

checkD.sh is not a replacement for defender.sh: it is meant only for cron so the process comes back after reboot or crash (uses nohup + lock file). If you already start/stop by hand with defender.sh, keep using that; add checkD.sh on a timer if you want an automatic safety net.

chmod +x checkD.sh
# crontab -e — example:
* * * * * /path/to/defender-master/checkD.sh >/dev/null 2>&1

See the top of checkD.sh for CHECKD_LOG, CHECKD_DEBUG, and CHECKD_LOG_EVERY_RUN.

Configuration

• defender.conf — hub server / port / password, linktype=p10, service identity (servername, sid, …), channel (control channel for operator commands), modules=…, paths, thresholds. On connect, verbose + version scan_user are always run before other modules (so dnsbl does not delay “Signed on” or CTCP VERSION); on quit / join / part / kill / nick change, verbose runs before the rest so seen (disk) and other hooks do not delay “Signed off” and similar lines. Optional control_channel_line_delay_ms spaces consecutive PRIVMSG to the control channel and globops when sends are within ~1.5s; unset means no delay (older trees mistakenly reused ipinfo_line_delay_ms for that — it is not used by ipinfo here). Automatic profile switch is controlled by attack_mode_auto, attack_mode_enter_conn_per_min, attack_mode_hold_sec. dnsbl reads dnsbl_cache_ttl, dnsbl_query_timeout_sec, dnsbl_cb_trigger_conn_per_min, dnsbl_cb_trigger_timeouts_per_min, dnsbl_cb_cooldown_sec, dnsbl_backlog_skip_ttl_sec plus attack_... overrides. ipinfo reads ipinfo_token, ipinfo_cache_ttl_sec, ipinfo_burst_limit, ipinfo_burst_window_sec, ipinfo_http_timeout_sec (see defender.conf.example).
• defender.conf is not committed (see .gitignore); use defender.conf.example as the template.
• Under datadir (see datadir= in defender.conf), usually not committed: dnsbl.conf, regexp_akill.conf, glines.conf, killchans.conf, deny_version.conf, defender_persistent_counters.v1, seen_state.sto (from the seen module). Beside defender.pl: defender.conf, defender.pid, and (if logto=Text) the file at logpath — often the same folder as datadir, but paths are independent. Templates: defender.conf.example → defender.conf next to defender.pl; deny_version.conf.example, dnsbl.conf.example, regexp_akill.conf.example → datadir with the names above. A commented cgiirc.conf may live at the project root in this tree; the running service reads $datadir/cgiirc.conf (create or copy there if you use the cgiirc module). Optional: seen_max_entries in defender.conf (default 10000) limits last-seen records.

Control channel & commands

Commands below are sent on the control channel set in defender.conf as channel. Replace <botnick> with your configured bot nick. On the uplink, IRC operator status is required for most operator commands (message.pl and several modules call isoper).

Core (message.pl)

Command	Operator?	Description
help	yes	Short index; lists each loaded module’s cmd_help line.
help <module>	yes	Help for one scan module name (as in modules=).
info	yes	Short network snapshot counts (servers / users / channels seen on the link).
info help	yes	Longer explanation of info subcommands and related lookups.
info servers	yes	List of server names from the P10 cache.
info users	yes	User counts grouped by uplink server.
info users list	yes	Capped flat list of cached nicks.
info chans	yes	Per-server channel name statistics (JOIN-derived; rows overlap).
info chans list / info channels list	yes	Capped flat list of distinct channel names seen.
status	yes	Process start time, uptime, metrics, loaded modules, link capabilities.
status all	yes	Same metrics plus stats output for every loaded scan module.
status <module>	yes	stats for scan modules whose name matches (e.g. status dnsbl).
<botnick> rehash	yes	Reload defender.conf and rescan module list (SIGHUP-style).
<botnick> shutdown	yes	Shut down Defender.

CTCP to the bot’s nick (VERSION, TIME, …) is answered in message.pl with rate limiting; not specific to scan modules.

Scan modules (modules=)

Only modules listed in defender.conf are active. Names must match Modules/Scan/<name>.pm without .pm.

Order: for each new client, scan_user runs in list order until a module calls gline() (that increments an internal counter and skips remaining modules for that client). Keep conn_average (and any other always-on counters) before modules that may G-line from scan_user (dnsbl, regexp_akill, cgiirc, etc.) so connection-rate stats stay accurate.

Module	What it does	Commands on the control channel
conn_average	Counts sign-ons per minute; if above conn_average_max, sends GLOBOPS; if conn_average_mirror_console is not 0, repeats the warning on the control channel. Can auto-enable global attack mode and (optionally) force emergency G-lines while attack mode is active.	None (automatic). Use status conn_average if stats is defined.
dnsbl	Checks new users against RBL zones from dnsbl.conf in datadir.	None (automatic).
version	CTCP VERSION fingerprinting / deny_version.conf rules (when version is in modules=). G-line duration for G rules is fixed in code (86400s). Global outbound CTCP limiting is configurable via version_ctcp_global_burst, version_ctcp_global_window_sec, version_ctcp_global_mute_sec (and attack_... overrides while attack mode is active).	version ctcp-all — sends CTCP VERSION to $*.net; oper. Replies still filtered by deny_version.conf.
regexp_akill	On sign-on, matches nick!ident@host + realname against regexes; G-lines on match (~600s). Off by default — add regexp_akill to modules= and maintain regexp_akill.conf if you use it.	regexp_akill add <pattern> <reason>, regexp_akill del <pattern>, regexp_akill list — oper; file regexp_akill.conf.
flood	Per-channel flood detection and temporary +f (and related) lock.	None (automatic).
nickflood	Kills rapid nick changes (nickflood_limit).	None (automatic).
killchan	G-lines non-opers who join listed channels after a grace period.	killchan add #channel reason, killchan del #channel, killchan list — oper; list stored in killchans.conf.
message	Logs private messages to the bot to the control channel and auto-replies once with support channel info.	No control-channel commands (PM-only behaviour).
verbose	Announces joins/parts/modes/KILLs/etc. on the control channel.	None (automatic).
gline	Manages G-lines (local cache + IRCd); syncs GL traffic from the link.	gline, gline help — help text. gline add …, gline del …, gline list, gline del all. Shorthand: gline <target> [time] [reason] (same as gline add). oper.
ipinfo	GeoIP / host info via ipinfo.io (token in defender.conf).	ip or ip <target> (address, hostname, or nick) — oper.
whois	Snapshot from the P10 client cache (not the IRCd’s full /WHOIS): user/host, IP, account if known, sign-on, server, channels, privileges. The command also requests live IRCd WHOIS away (301), idle (317) and account (330) and prints them when received.	whois <nick> or whois nick <nick> — oper.
seen	Last quit / kill for a nick, or online from the P10 cache (server/channels). For online users it can trigger live IRCd away lookup to correct stale pre-link away state. Changing nick removes the old nick from last-seen.	seen <nick> — oper; datadir/seen_state.sto (pruned, persisted).
cgiirc	Detects unauthorised CGI:IRC via VERSION notices; optional cgiirc.conf whitelist.	None (automatic).

To see the exact help string a module registers, use help <module> on the control channel (same text as in the bot output).

Away / live WHOIS data: away state in the P10 cache is accurate after relevant A lines have been seen while Defender is linked. Users already away before link-up can be stale; whois now asks IRCd live away (301) and seen can request live away for online users, so displayed state is corrected on demand. whois also asks for live idle (317) and account (330); if idle reply does not arrive within timeout, it reports n/a (IRCd timeout).

Project layout (high level)

Path	Role
defender.pl	Entry point
message.pl	PRIVMSG/NOTICE routing, CTCP, help text
Modules/Main.pm	Config load, module wiring
Modules/Link/p10.pm	P10 uplink
Modules/Scan/*	Scan / policy modules
Modules/Log/Text.pm	File logging (logto=Text)
defender.sh	Manual start / stop / restart / status
checkD.sh	Cron watchdog only (auto restart after reboot/crash)
defender.conf.example	Config template: copy to defender.conf in the same directory as defender.pl (not necessarily datadir; see datadir= for policy files)
deny_version.conf.example	Template for the version module’s deny_version.conf in datadir
dnsbl.conf.example	Template for dnsbl.conf (Config::General: RBL zones, duration, reason, <reply>)
regexp_akill.conf.example	Template for regexp_akill.conf (tab: regex, reason); use only if regexp_akill is in modules=

License

This program is free software licensed under the GNU General Public License v2.0 — see the LICENSE file. Running perl defender.pl --help also references GPL v2.

Bundled third-party code (for example under Config/ and Tie/) retains its own copyright and license notices in the respective files.

Contributing

Issues and pull requests are welcome. Do not commit secrets: keep defender.conf, API tokens, and hub passwords out of git (use defender.conf.example only for structure).

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Defender is an IRC network tool: use it only on networks and systems you are allowed to administer.