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multi-bogon-nft-blocklist.pl
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multi-bogon-nft-blocklist.pl
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#!/usr/bin/perl
# (c) 2022 Leif Sawyer
# License: GPL 3.0 (see https:/akhepcat/)
# Permanent home: https:/akhepcat/Miscellaneous/
# Direct download: https://raw.githubusercontent.com/akhepcat/Miscellaneous/master/multi-bogon-nft-blocklist.pl
#
use Net::Netmask;
use JSON::Parse 'parse_json';
use Data::Dumper;
use Scalar::Util qw(reftype);
##############################################
## Configuration data
##############################################
# Which sources should be enabled? at least one, or this breaks...
my $DSHIELD=1;
my $CYMRU=1;
my $SHDROP=1;
my $SHEDROP=1;
my @always_block=("0.0.0.0/8", "100.64.0.0/10", "127.0.0.0/8", "169.254.0.0/16", "192.0.0.0/24", "192.0.2.0/24", "198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "224.0.0.0/3" );
# localhosts, aws
my @never_block=("192.168.0.0/22", "54.240.0.0/18" );
my @cidrs;
my $DEBUG=0; # 0 for production, 1 will echo the commands to be run
##############################################
## Program follows
##############################################
my $sysconf="/etc/default/multibl.conf"; # by default...
if (open(CONF, "<$sysconf")) {
my @t; my $var;
while(<CONF>) {
chomp;
my $i;
if (m/^[[:space:]]*([[:alpha:]]+)=(.*)/) {
$var=$1; $_=$2;
s/\s+#.*//; s/"//; # remove comments and floating quotes
print "DBG: configfile discovered var '$var' with contents " . $_ . "\n" if $DEBUG;
if ($var eq "DSHIELD") {
$DSHIELD=$_;
} elsif ( $var eq "CYMRU" ) {
$CYMRU=$_;
} elsif ( $var eq "SHDROP") {
$SHDROP=$_;
} elsif ( $var eq "SHEDROP") {
$SHEDROP=$_;
} elsif ( $var eq "DEBUG") {
$DEBUG=$_;
} else {
foreach $i (split /,/, $_) {
push @t, $i;
}
if (scalar @t >=1 ) {
if ($var eq "always_block") {
push(@always_block,@t);
} elsif ($var eq "user_block") {
push(@always_block,@t);
} elsif ($var eq "never_block") {
push(@never_block,@t);
}
}
}
}
}
close(CONF);
} else {
print "can't open $sysconf, using hard-coded defaults\n";
}
if ($DSHIELD + $CYMRU + $SHDROP + $SHEDROP < 1) {
print "ERROR: No blocklist sources configured\n";
exit(1);
}
open(NFT, "nft -s -nnn list set netdev filter blocklist_v4 -j |" ) || die "can't open nft to import blocklist_v4 filter";
while(<NFT>) {
$json.="$_";
}
# Ugh, working our way through the json output is... horrible.
my $parsed=parse_json($json);
my @arr1 = @{$parsed->{nftables}};
my @arr2 = @{$arr1[1]->{set}->{elem}};
my $max = $#arr2;
for ( $i=0; $i < $max +1; $i++) {
my %prefix;
my @range;
my $cidr;
my $c;
my $lp=0;
my %hash1 = %{@arr2[$i]};
if ( defined($hash1{prefix}) ) {
%prefix = %{$hash1{prefix}};
$cidr=$prefix{addr} . "/" . $prefix{len};
} elsif (defined($hash1{range})) {
my @v1 = $hash1{range};
my @range = @{$v1[0]};
$cidr = Net::Netmask->safe_new($range[0] . "-" . $range[1])->desc();
} else {
next;
}
next if (!defined($cidr));
foreach my $abn (@always_block) {
my $ab = Net::Netmask->safe_new($abn);
$c = Net::Netmask->safe_new($cidr);
if ( ($ab->contains($c) eq 0) and ($c->contains($ab) eq 0) ) {
$lp++;
}
}
if ( $lp gt 0 ) {
print "removing $cidr from blocklist\n" if $DEBUG;
push @cidrs, $c;
}
}
my @tcidrs = cidrs2cidrs(@cidrs); #collapse the IP subnets to their smallest functions
@cidrs=();
foreach my $tc (@tcidrs) { # convert back to text
push(@cidrs, $tc->desc() );
}
my $rcidrs = join(',', @cidrs);
if (scalar @cidrs >=1 ) {
if ($DEBUG == 1) {
print qq|/sbin/nft delete element netdev filter blocklist_v4 "{ $rcidrs }"\n|;
} else {
system(qq|/sbin/nft delete element netdev filter blocklist_v4 "{ $rcidrs }"\n|);
}
}
# From here it will be an array of Net::Netmasks
@cidrs=();
if ($DSHIELD == 1 ) {
# Top-20 attacking /24's over the last three days; updates every hour
open(RPT, qq!curl -silent https://feeds.dshield.org/block.txt | grep -E '^[0-9]+' | awk '{print \$1 "/" \$3}'| !) || die "can't read cidrs from dshield report";
while (<RPT>) {
chomp;
if (m/([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\/[0-9]{1,2})/) {
push(@cidrs, Net::Netmask->safe_new($1) );
}
}
close(RPT);
}
if ($CYMRU == 1 ) {
# Textual Full bogon list, updates every four hours
open(RPT, qq!curl -silent https://www.team-cymru.org/Services/Bogons/fullbogons-ipv4.txt | grep -E '^[0-9]+'| !) || die "can't read cidrs from cymru fullbogon report";
while (<RPT>) {
chomp;
if (m/([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\/[0-9]{1,2})/) {
push(@cidrs, Net::Netmask->safe_new($1) );
}
}
close(RPT);
}
if ($SHDROP == 1 ) {
# SpamHaus Don't Route or Peer list, updates once per day
open(RPT, qq!curl -silent https://www.spamhaus.org/drop/drop.txt | grep -E '^[0-9]+' | cut -f1 -d";" | !) || die "can't read cidrs from cymru fullbogon report";
while (<RPT>) {
chomp;
if (m/([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\/[0-9]{1,2})/) {
push(@cidrs, Net::Netmask->safe_new($1) );
}
}
close(RPT);
}
if ($SHEDROP == 1 ) {
# SpamHaus Extended Don't Route or Peer list, updates once per day
open(RPT, qq!curl -silent https://www.spamhaus.org/drop/edrop.txt | grep -E '^[0-9]+' | cut -f1 -d";" | !) || die "can't read cidrs from cymru fullbogon report";
while (<RPT>) {
chomp;
if (m/([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\/[0-9]{1,2})/) {
push(@cidrs, Net::Netmask->safe_new($1) );
}
}
close(RPT);
}
my @bcidrs=();
@cidrs = cidrs2cidrs(@cidrs); #collapse the IP subnets to their smallest functions
foreach $cidr (@cidrs) {
my $block = 1;
foreach $permit (@never_block)
{
my $test = Net::Netmask->safe_new($permit);
if ( $cidr->contains($test) eq 1 or $test->contains($cidr) eq 1 ) {
$block = 0;
}
}
if ($block eq 1) {
# print "Adding block for $cidr\n";
push @bcidrs, $cidr->desc();
}
}
if (scalar @bcidrs >= 1) {
my $bcd = join(',', @bcidrs);
if ($DEBUG == 1) {
print qq|/sbin/nft add element netdev filter blocklist_v4 "{ $bcd }"\n|;
} else {
system(qq|/sbin/nft add element netdev filter blocklist_v4 "{ $bcd }"\n|);
}
}