The "dnsbl" Module (v4)

Description

This module allows the server administrator to check the IP address of connecting users against a DNSBL. This is useful for preventing malicious hosts from connecting to the server.

Configuration

To load this module use the following <module> tag:

<module name="dnsbl">

<connect>

This module extends the core <connect> tags with the following fields:

Name	Type	Default Value	Description
dnsbl	Text	None	Match users to this connect class by DNSBL name when using the mark action.
usednsbl	Boolean	Yes	Whether users in this connect class should be looked up in a DNSBL.

Example Usage

Disables DNSBL lookups for users in the WebChat class:

<connect name="WebChat"
         ...
         usednsbl="no">

Matches users that have been marked by a configured DNSBL named Proxies to a ProxyUser class:

<connect name="ProxyUser"
         ...
         dnsbl="Proxies">

<dnsbl>

The <dnsbl> tag defines a DNSBL to check connecting users against. This tag can be defined as many times as required.

Name	Type	Default Value	Description
action	Text	None	Required! The action to take against users who's IP address is in this DNSBL.
bitmask	Number	None	Required for the bitmask type! Deprecated! A bitmask of DNSBL result types to match against.
domain	Text	None	Required! The domain name of this DNSBL.
duration	Duration	1h	If action is set to gline, kline, or zline then the duration for an X-line to last for.
host	Text	None	If action is set to mark then a new hostname to set on users who's IP address is in this DNSBL.
user	Text	None	If action is set to mark then a new username to set on users who's IP address is in this DNSBL.
name	Text	None	Required! The human readable name of this DNSBL.
reason	Text	Your IP (%ip%) has been blacklisted by the %dnsbl% DNSBL.	The message to send to users who's IP address is in a DNSBL.
records	No. Range	None	Required for the record type! A numeric range of DNSBL result types to match against.
timeout	Duration	Depends on <dns:timeout>	The time period to wait for a response from this DNSBL.
type	Text	record	The type of result that this DNSBL will provide.

The action field should be set to one of the following values:

Value	Description
gline	G-line users who's IP address is in the DNSBL.
kill	Kill users who's IP address is in the DNSBL.
kline	K-line users who's IP address is in the DNSBL.
mark	Marks users who's IP address is in the DNSBL.
zline	Z-line users who's IP address is in the DNSBL.

The reason field can contain any of the following template variables:

Variable	Description
%dnsbl%	The name of the DNSBL (from <dnsbl:name>)
%dnsbl.url%	New in v4.1.0! The name of the DNSBL (from <dnsbl:name>) encoded for use in an URL.
%ip%	The IP address of the user.
%network%	New in v4.1.0! The name of the IRC network (from <server:network>).
%network.url%	New in v4.1.0! The name of the IRC network (from <server:network>) encoded for use in an URL.
%reason%	New in v4.4.0! A human readable description of the DNSBL result (from <dnsblreply>).
%result%	The record type returned by the DNSBL.

The type field should be set to one of the following values:

Value	Description
bitmask	Deprecated! DNSBL results will be compared against the bit mask specified in the bitmask field to see if the IP address in question is in a DNSBL. For example, 15 would match against DNSBL result types 1, 2, 4, and 8.
record	DNSBL results will be compared against a numeric range of values. For example, 1-3,4,5 would match all DNSBL result types between 1 and 5.

Example Usage

DroneBL is a DNSBL for IRC networks:

<dnsbl name="DroneBL"
       domain="dnsbl.dronebl.org"
       type="record"
       records="3,5,6,7,8,9,10,11,13,14,15,16,17,19"
       action="zline"
       duration="7d"
       reason="You are listed in DroneBL. Please visit https://dronebl.org/lookup?ip=%ip% for more information.">

EFnet RBL is a DNSBL of undesirable IP addresses detected by the EFnet IRC Network:

<dnsbl name="EFnet RBL"
       domain="rbl.efnetrbl.org"
       type="record"
       records="1,2,3,4,5"
       action="zline"
       duration="7d"
       reason="You are listed in the EFnet RBL. Please visit https://rbl.efnetrbl.org/?i=%ip% for more information.">

torexit.dan.me.uk is a DNSBL of Tor exit nodes.

<dnsbl name="torexit.dan.me.uk"
       domain="torexit.dan.me.uk"
       type="record"
       records="100"
       timeout="10s"
       action="zline"
       duration="7d"
       reason="Tor exit nodes are not allowed on this network. See https://metrics.torproject.org/rs.html#search/%ip% for more information.">

<dnsblreply>

The <dnsblreply> tag defines the meaning of a reply from a DNSBL. This tag can be defined as many times as required.

Name	Type	Default Value	Description
name	Text	None	Required! The name of the DNSBL this reply applies to.
reply	Number	None	Required! The DNSBL reply that this tag specifies a meaning for.
description	Text	None	Required! A human readable description of the DNSBL reply.

Example Usage

Specifies that a result of 42 from the SpamBL DNSBL means that the user is connecting from an infected host.

<dnsblreply name="SpamBL"
            reply="42"
            description="Infected host">

Server Notice Masks

Character	Description
d	Notifications about DNSBL hits on the local server.
D	Notifications about DNSBL hits on a remote server.

Statistics

Character	Description
d	Lists information about DNSBL hits and misses.

Special Notes

If you are also using the gateway module you should disable DNSBL lookups for your WebIRC gateway.