francoisfernando

Java, do you trust me? 🤔

Using openssl to test an SSL connection to google.com, using a CA file that's been pulled out from a Java keystore. For those days when you want to verify that you've got the right certificate in the store:

Download the Equifax root certificate (which is the root CA for Google)
Import the certificate into a new Java keystore
Export the certificate back out again
Convert the certificate to PEM
Use openssl to test an SSL connection to Google with that cert

Create a new repository, or reuse an existing one.

Generate a new SSH key:

ssh-keygen -t rsa -C "[email protected]"

Copy the contents of the file ~/.ssh/id_rsa.pub to your SSH keys in your GitHub account settings (https://github.com/settings/keys).

Test SSH key:

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

	# Below are the dependencies required for installing the common combination of numpy, scipy, pandas and matplotlib
	# in an Alpine based Docker image.
	FROM alpine:3.4
	RUN echo "http://dl-8.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories
	RUN apk --no-cache --update-cache add gcc gfortran python python-dev py-pip build-base wget freetype-dev libpng-dev openblas-dev
	RUN ln -s /usr/include/locale.h /usr/include/xlocale.h
	RUN pip install numpy scipy pandas matplotlib

	# Compile and install certificates for the Java trust keystore
	# and main keystore. Let's face it, this is everyone's keystore password.
	# Note I install java very flatly normally.
	COPY trust-certs/ /usr/local/share/ca-certificates/
	RUN update-ca-certificates && \
	ls -1 /usr/local/share/ca-certificates \| while read cert; do \
	openssl x509 -outform der -in /usr/local/share/ca-certificates/$cert -out $cert.der; \
	/java/bin/keytool -import -alias $cert -keystore /java/jre/lib/security/cacerts -trustcacerts -file $cert.der -storepass changeit -noprompt; \
	rm $cert.der; \
	done

	import javax.net.ssl.SSLParameters;
	import javax.net.ssl.SSLSocket;
	import javax.net.ssl.SSLSocketFactory;
	import java.io.*;

	/** Establish a SSL connection to a host and port, writes a byte and
	* prints the response. See
	* http://confluence.atlassian.com/display/JIRA/Connecting+to+SSL+services
	*/
	public class SSLPoke {

	So you've cloned somebody's repo from github, but now you want to fork it and contribute back. Never fear!

	Technically, when you fork "origin" should be your fork and "upstream" should be the project you forked; however, if you're willing to break this convention then it's easy.

	* Off the top of my head *

	1. Fork their repo on Github
	2. In your local, add a new remote to your fork; then fetch it, and push your changes up to it

	git remote add my-fork [email protected]