mrmichalis

Using AWS Linux setup an L2TP/IPSEC Soft Ether VPN

Consider HVM (SSD) EBS-Backed 64-bit m3.medium

• us-east-1 => ami-1ecae776

• Updates and dependencies

sudo yum -y update
sudo yum -y upgrade
sudo yum -y install docker git wget

mrmichalis

OpenSSL Cheatsheet

Generating Certificates

Generate RSA Private Key + CSR
openssl req -out newkey.csr -new -newkey rsa:[bits] -nodes -keyout priv.key

Generate Self Signed Certificate + Priv Key
openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:[bits] -keyout priv.key -out cert.crt

mrmichalis

What is Avro?

Parsing the ga4gh API requires you first to understand what is Avro.

Avro is a project that allows you to

• formaly declare and define data structures (schemas in Avro) to be later used in different languages.
• store data in a file
• fetch data from a file

mrmichalis

How can I take thread dumps from a JVM on UNIX or Windows?

A thread dump is a list of all the Java threads that are currently active in a Java Virtual Machine (JVM).

There are several ways to take thread dumps from a JVM. It is highly recommended to take more than 1 thread dump. A good practice is to take 10 thread dumps at a regular interval (for example, one thread dump every ten seconds).

Step 1: Get the PID of your Java process

The first piece of information you will need to be able to obtain a thread dump is your Java process's PID.

The Java JDK ships with the jps command which lists all Java process ids. You can run this command like this:

mrmichalis

watch --difference=cummulative --interval=1 '(echo device read_IOs read_merges read_sectors read_ticks write_IOs write_merges write_sectors write_ticks in_flight io_ticks time_in_queue; for file in /sys/block/*/stat; do echo -n $file; cat $file; done) | column -t'
# OUTPUTS:
#device                 read_IOs  read_merges  read_sectors  read_ticks  write_IOs  write_merges  write_sectors  write_ticks  in_flight  io_ticks  time_in_queue
#/sys/block/dm-0/stat   116962    0            2212746       314096      7705653    0             150218536      609670232    0          644428    610921004
#/sys/block/dm-1/stat   116479    0            2208882       313324      7686986    0             150218536      609676068    0          644616    611418072
#/sys/block/dm-2/stat   302       0            2416          780         0          0             0              0            0          148       780
#/sys/block/sda/stat    91181     26273        2217246       74876       7314854    388030        150261802      16954364 

mrmichalis

cat << EOF > HttpsClient.java
// purpose; connecto to an HTTPS site and display certificate chain, validity, owner, issuer, SNI

import java.net.MalformedURLException;
import java.net.URL;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import java.security.cert.*;
import java.io.*;
import java.util.*;