NAME¶
Net::RBLClient - Queries multiple Realtime Blackhole Lists in parallel
SYNOPSIS¶
use Net::RBLClient;
my $rbl = Net::RBLClient->new;
$rbl->lookup('211.101.236.160');
my @listed_by = $rbl->listed_by;
DESCRIPTION¶
This module is used to discover what RBL's are listing a particular IP address.
It parallelizes requests for fast response.
An RBL, or Realtime Blackhole List, is a list of IP addresses meeting some
criteria such as involvement in Unsolicited Bulk Email. Each RBL has its own
criteria for addition and removal of addresses. If you want to block email or
other traffic to/from your network based on one or more RBL's, you should
carefully study the behavior of those RBL's before and during such blocking.
CONSTRUCTOR¶
- new( [ARGS] )
- Takes an optional hash of arguments:
- lists
- An arraref of (sub)domains representing RBLs. In other words, each element
in the array is a string similar to 'relays.somerbl.org'. Use this if you
want to query a specific list of RBL's - if this argument is omitted, a
large list of RBL's is queried.
- query_txt
- Set this to true if you want Net::RBLClient to also query for TXT records,
in which many RBL's store additional information about the reason for
including an IP address or links to pages that contain such information.
You can then retrieve these information using the "
txt_hash()" method.
- max_time
- The maximum time in seconds that the lookup function should take. In fact,
the function can take up to "max_time + timeout" seconds.
Max_time need not be integer. Of course, if the lookup returns due to
max_time, some DNS replies will be missed.
Default: 8 seconds.
- timeout
- The maximum time in seconds spent awaiting each DNS reply packet. The only
reason to change this is if "max_time" is decreased to a small
value.
Default: 1 second.
- max_hits
- A hit is an affirmative response, stating that the IP address is on a
certain list. If "max_hits" hits are received,
"lookup()" returns immediately. This lets the calling program
save time.
Default: 1000 (effectively out of the picture).
- max_replies
- A reply from an RBL could be affirmative or negative. Either way, it
counts towards "max_replies". "Lookup()" returns when
"max_replies" replies have been received.
- udp_maxlen
- The maximum number of bytes read from a DNS reply packet. There's probably
no reason to change this.
Default: 4000
- server
- The local nameserver to use for all queries. Should be either a resolvable
hostname or a dotted quad IP address.
By default, the first nameserver in /etc/resolv.conf will be used.
METHODS¶
- lookup( IPADDR )
- Lookup one IP address on all RBL's previously defined. The IP address must
be expressed in dotted quad notation, like '1.2.3.4'. "Lookup()"
returns 1.
- listed_by()
- Return an array of RBL's which block the specified IP. The RBL's are
indicated via the (sub)domain used for DNS query. The calling program must
first call "lookup()".
- listed_hash()
- Return a hash whose keys are the RBL's which block the specified IP,
represented as in "listed_by()". If the RBL returned an A
record, the value for that key will be the IP address in the A record -
typically 127.0.0.1 - 127.0.0.4. If the RBL returned a CNAME, the value
will be the hostname, typically used for a comment on why the IP address
is listed.
- txt_hash()
- Return a hash (or a reference to that hash if called in a scalar context)
whose keys are the RBL's which block the specified IP, represented as in
"listed_by()". If the RBL returned TXT records containing
additional information, the value will contain this information (several
TXT records from one RBL will be joined by semicolons, but this should not
happen), if not, it will be undef.
AUTHOR¶
Asher Blum <
asher@wildspark.com>
CREDITS¶
Martin H. Sluka <
martin@sluka.de>
COPYRIGHT¶
Copyright (C) 2002 Asher Blum. All rights reserved. This code is free software;
you can redistribute it and/or modify it under the same terms as Perl
itself.