gocert

A small go program to print details on X509 certificates and safe them in .pem format.

Why?

• Because I can never remember openssl's syntax. The s_client -connect is not intuitive.
• Because I want a better way for displaying certificates, with emphasis on what matters.
• Because I want to be able to extract remote certificates .pem's easily

Installation

• Just build gocert.go and move it somewhere in your path. For example, if you are running OSX (this you already have the GO environment installed):

  cd /tmp; curl -O https://raw.github.com/diogomonica/gocert/master/gocert.go; go build gocert.go; mv gocert /usr/local/bin

Usage

usage: gocert [-save] [-chain] hostname:port
  -chain=false: Print details about all the certificates on the chain
  -save=false: Save the PEM to the local disk in the format of #{CN}.pem

Examples

Retrieving information about the certificate of diogomonica.com:

# gocert diogomonica.com:443	
CommonName: www.diogomonica.com - []
Issuer: StartCom Class 1 Primary Intermediate Server CA - [StartCom Ltd.]
Alt Names: [www.diogomonica.com diogomonica.com]
Expires in: 359 days
Version: 3 ; Serial: 516289
BasicConstraintsValid: true ; IsCA: false ; MaxPathLen: -1
--------------------

Retrieving information about the full chain of diogomonica.com:

# gocert -chain diogomonica.com:443
CommonName: www.diogomonica.com - []
Issuer: StartCom Class 1 Primary Intermediate Server CA - [StartCom Ltd.]
Alt Names: [www.diogomonica.com diogomonica.com]
Expires in: 359 days
Version: 3 ; Serial: 516289
BasicConstraintsValid: true ; IsCA: false ; MaxPathLen: -1
--------------------
CommonName: StartCom Class 1 Primary Intermediate Server CA - [StartCom Ltd.]
Issuer: StartCom Certification Authority - [StartCom Ltd.]
Alt Names: []
Expires in: 1816 days
Version: 3 ; Serial: 24
BasicConstraintsValid: true ; IsCA: true ; MaxPathLen: -1
--------------------
CommonName: StartCom Certification Authority - [StartCom Ltd.]
Issuer: StartCom Certification Authority - [StartCom Ltd.]
Alt Names: []
Expires in: 8719 days
Version: 3 ; Serial: 1
BasicConstraintsValid: true ; IsCA: true ; MaxPathLen: -1
--------------------

Retrieving and saving in PEM format the certificate of diogomonica.com:

# gocert -save diogomonica.com:443
CommonName: www.diogomonica.com - []
Issuer: StartCom Class 1 Primary Intermediate Server CA - [StartCom Ltd.]
Alt Names: [www.diogomonica.com diogomonica.com]
Expires in: 359 days
Version: 3 ; Serial: 516289
BasicConstraintsValid: true ; IsCA: false ; MaxPathLen: -1
--------------------
# * ls -alh www.diogomonica.com.pem 
-rw-r--r--  1 diogo  diogo   2.8K Nov  2 22:19 www.diogomonica.com.pem