Copy Whole Disk over Network

rsync -axv -e ssh root@source:/ /mnt/root

Disk Encryption Using LUKS

Load device mapper, encrypt partition, optionally add second passphrase, open encrypted partition and format it using ReiserFS:

moprobe dm-mod
cryptsetup -c aes-xts-plain -y -s 512 luksFormat /dev/sda1
cryptsetup luksAddKey /dev/sda1
cryptsetup luksOpen /dev/sda1 root
mkfs.reiserfs -l ROOT /dev/mapper/root

PostgreSQL Timestamp and Unix Time Conversions

PostgreSQL timestamp to Unix time:

postgres=# select extract(epoch from timestamp with time zone '2011-01-02 03:04:05+06');
 date_part  
------------
 1293915845
(1 row)

Unix time to PostgreSQL timestamp:

postgres=# select to_timestamp(1293915845);
      to_timestamp      
------------------------
 2011-01-01 22:04:05+01
(1 row)

Capture and Replay Network Traffic

Example of capturing and replaying captured syslog traffic.

Capture:

tcpdump -v -s 0 -w syslog.dump -nn udp dst port 514

Rewrite:

tcprewrite --fixcsum \
           --enet-dmac=00:11:22:33:44:55 \
           --dstipmap=0.0.0.0/0:1.2.3.4/32 \
           --infile=syslog.dump \
           --outfile=syslog.redump

Replay:

tcpreplay -i eth0 --topspeed syslog.redump
tcpreplay -i eth0 --mbps=5.0 syslog.redump

POE::Component::Client::DNS

Examples of resolving a "large" number of domains in parallel using asynchronous DNS calls.

Version 3 API

	#!/usr/bin/env perl
	use strict;
	use warnings;
	use POE;
	use POE::Component::Client::DNS;
	my @ips = qw( 127.0.0.1 10.0.0.1 192.168.0.1 192.168.1.1 1.2.3.4
	8.8.4.4 8.8.8.8 208.67.220.220 208.67.222.222 );
	my $resolver = POE::Component::Client::DNS->spawn(
	Alias => 'resolver',
	Timeout => 10,
	);
	POE::Session->create(
	inline_states => {
	_start => sub { $_[KERNEL]->yield('lookup') for 1..5; },
	lookup => sub {
	my $ip = shift @ips;
	return unless defined $ip;
	# Example of using POE::Component::Client::DNS Version 3 API
	my $response = $resolver->resolve(
	event => 'response',
	host => $ip,
	type => 'PTR',
	context => { },
	);
	$_[KERNEL]->yield(response => $response) if $response;
	},
	response => sub {
	my $request_address = $_[ARG0]->{'host'};
	my $net_dns_packet = $_[ARG0]->{'response'};
	my $net_dns_errorstring = $_[ARG0]->{'error'};
	unless ( defined $net_dns_packet ) {
	print "$request_address: error ($net_dns_errorstring)\n";
	$_[KERNEL]->yield('lookup');
	return;
	}
	my @net_dns_answers = $net_dns_packet->answer();
	unless ( scalar @net_dns_answers ) {
	print "$request_address: no answer\n";
	$_[KERNEL]->yield('lookup');
	return;
	}
	foreach ( @net_dns_answers ) {
	if ( $_->type eq "PTR" ) {
	( my $fqdn = $_->rdatastr ) =~ s/\.$//;
	print "$request_address: $fqdn\n";
	last;
	}
	}
	$_[KERNEL]->yield('lookup');
	},
	}
	);
	$poe_kernel->run();
	exit 0;

view raw dns-3.pl hosted with ❤ by GitHub

Version 2 API

	#!/usr/bin/env perl
	use strict;
	use warnings;
	use POE;
	use POE::Component::Client::DNS;
	my @ips = qw( 127.0.0.1 10.0.0.1 192.168.0.1 192.168.1.1 1.2.3.4
	8.8.4.4 8.8.8.8 208.67.220.220 208.67.222.222 );
	my $resolver = POE::Component::Client::DNS->spawn(
	Alias => 'resolver',
	Timeout => 10,
	);
	POE::Session->create(
	inline_states => {
	_start => sub { $_[KERNEL]->yield('lookup') for 1..5; },
	lookup => sub {
	my $ip = shift @ips;
	return unless defined $ip;
	# Example of using POE::Component::Client::DNS Version 2 API
	$_[KERNEL]->post( 'resolver',
	'resolve',
	'response',
	$ip, 'PTR', 'IN' );
	},
	response => sub {
	my $request_address = $_[ARG0]->[0];
	my ( $net_dns_packet, $net_dns_errorstring ) = @{ $_[ARG1] };
	unless ( defined $net_dns_packet ) {
	print "$request_address: error ($net_dns_errorstring)\n";
	$_[KERNEL]->yield('lookup');
	return;
	}
	my @net_dns_answers = $net_dns_packet->answer();
	unless ( scalar @net_dns_answers ) {
	print "$request_address: no answer\n";
	$_[KERNEL]->yield('lookup');
	return;
	}
	foreach ( @net_dns_answers ) {
	if ( $_->type eq 'PTR' ) {
	( my $fqdn = $_->rdatastr ) =~ s/\.$//;
	print "$request_address: $fqdn\n";
	last;
	}
	}
	$_[KERNEL]->yield('lookup');
	},
	}
	);
	$poe_kernel->run();
	exit 0;

view raw dns-2.pl hosted with ❤ by GitHub