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https://github.com/Ponce/slackbuilds
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179 lines
4.8 KiB
Smarty
179 lines
4.8 KiB
Smarty
#!/usr/bin/perl -wT
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# Copyright 2009 Kagan D. MacTane
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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require 5.004;
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use strict;
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use Sys::Syslog;
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# -------------------------------------------------------------------
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# This option *MUST* match the corresponding value in sshblock.pl!
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my $history_file = '/etc/ssh/block-history';
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# Blocking duration formula: If blocking for the Nth time, and
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# b = $base and m = $mult, then block for:
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#
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# T = m * ( b ^ (N-1) )
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#
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# Time T is expressed in hours.
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my $base = 4;
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my $mult = 3;
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my $Syslog_Level = 'info';
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my $Syslog_Facility = 'user';
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my $Syslog_Options = '';
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my $VERSION = 0.5;
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$ENV{'PATH'} = '/bin:/usr/bin:/usr/sbin:/sbin';
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# -------------------------------------------------------------------
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# Abort if you're not running as root
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if ($>) {
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print "Only root can run this program.\n";
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exit 1;
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}
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my $now = time();
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my @history;
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open FH, "$history_file" || exit 7;
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@history = <FH>;
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close FH;
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my @input_chain = `iptables -nL INPUT | tail +3`;
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# Your iptables output needs to look like:
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# DROP tcp -- 1.2.3.4 0.0.0.0/0 tcp dpt:22 flags:0x17/0x02
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if (scalar @input_chain > 0) {
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LogMessage("Checking ".scalar @input_chain." blocked IPs against ".scalar @history." block-history entries.");
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}
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foreach my $item (@input_chain) {
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my @stats = split(/\s+/, $item);
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next unless ($stats[0] eq 'DROP');
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next unless ($stats[1] eq 'tcp');
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next unless ($stats[6] eq 'dpt:22');
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next unless ($stats[7] eq 'flags:0x17/0x02');
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my $curr_ip = $stats[3];
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if ($curr_ip =~ /^(\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b)$/) {
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$curr_ip = $1;
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} else {
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LogMessage("Invalid IP address in output from iptables?!?");
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next;
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}
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for ( my $i = 0; $i < scalar @history; $i++ ) {
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my $hist_ip = (split(/\t/, $history[$i]))[0];
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if ((split(/\t/, $history[$i]))[0] eq $curr_ip) {
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my ($times_blocked, $blocked_since) = (split(/\t/, $history[$i]))[1,2];
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my $duration = $now - $blocked_since;
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$duration /= 3600;
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$duration = sprintf("%.2f", $duration);
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my $block_for = $mult * ($base ** ($times_blocked - 1));
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if ($duration > $block_for) {
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`iptables -D INPUT -p tcp -s $curr_ip --dport 22 --syn -j DROP`;
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if ($?) {
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LogMessage("Couldn't unblock IP $curr_ip (now blocked for $duration hours)! Error $?: $!");
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} else {
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LogMessage("Unblocked IP $curr_ip after $duration hours.");
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}
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}
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}
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}
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}
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exit 0;
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sub is_blocked {
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my $ip_addr = shift;
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return grep /^$ip_addr/, split /\n/, `iptables -nL | grep DROP | grep 'dpt:22' | grep '0x17/0x02' | awk '{print \$4}'`;
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}
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sub LogMessage {
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my $format = shift;
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openlog('sshblock', $Syslog_Options, $Syslog_Facility);
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syslog($Syslog_Level, $format, @_);
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closelog();
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}
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__END__
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=head1 NAME
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sshunblock.pl - SSH dictionary attack (un)blocker
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=head1 SYNOPSIS
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B<sshblock.pl>
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=head1 DESCRIPTION
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This is part of the SSHblock system; the B<sshunblock.pl> executable is responsible for unblocking blocked IP addresses after a suitable length of time has passed. It does this by removing the B<iptables> firewall rules created by B<sshblock.pl>. In order to use iptables, sshunblock.pl must be run as root.
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=head1 INVOCATION
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B<sshunblock.pl> is intended to be called as an hourly cron(8) job. Calling it more or less frequently will not interfere with its operation.
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By default, SSHblock logs its activity to syslog(8), using the "user" facility at level "info".
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=head1 CONFIGURATION
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F<sshunblock.pl> can be configured by changing the following options in the program's source code.
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=over
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=item B<$history_file>
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Note that B<this option MUST match the value in sshblock.pl!> This is where SSHblock should store its history file. This file keeps a record of all IP addresses SSHblock has ever blocked, one per line. Each line consists of three tab-delimited fields: the IP address; the total number of times it's been blocked; and the timestamp it was last blocked at.
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=item B<$base, $mult>
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These control the behavior of SSHblock's exponential increase algorithm. By tweaking these, you can make SSHblock block attacking IP addresses for longer or shorter periods of time.
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=back
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=head1 FILES
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=over
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=item F</etc/ssh/block-history>
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=back
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=head1 BUGS
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Please let me know if you find any.
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=head1 AUTHOR
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Kagan D. MacTane (kai@mactane.org)
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=head1 SEE ALSO
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sshblock(8), iptables(8), L<http://sourceforge.net/projects/swatch/>
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=cut
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