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Feb 04 / 2019
0

Linux

Fix the NO_PUBKEY error with apt on Ubuntu

When updating or installing a package on a Debian-based distribution, you can face that alert:

W: GPG error: http://ppa.launchpad.net trusty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C2518248EEA14886

1	W: GPG error: http://ppa.launchpad.net trusty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C2518248EEA14886

This just means that a signing GPG key is missing or expired on your system. The error is giving you the ID of the missing key that you can use for looking for it on the Ubuntu website:

http://keyserver.ubuntu.com:11371/pks/lookup?op=get&search=0xC2518248EEA14886

1	http://keyserver.ubuntu.com:11371/pks/lookup?op=get&search=0xC2518248EEA14886

Copy the key that you just got from the website above into a file – mykey.txt, for example – and import it with the apt-key command:

apt-key add mykey.txt

1	apt-key add mykey.txt

Try to install/update the package again, and the error should not appear anymore.

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Sep 27 / 2018
0

Uncategorized

Extract certificate and/or key from a PKCS12 file

The PKCS12 format is replacing the old PFX format from Microsoft. This format will allow storage of X.509 private keys and the associated public certificates in a single encrypted file.

So you can extract the key and the certificate in a single common PEM file, you can use this openssl command:

openssl pkcs12 -in myCertificate.pfx -out myCertificateAndMyKey.pem

1	openssl pkcs12 -in myCertificate.pfx -out myCertificateAndMyKey.pem

If you want to extract the key and the certificate independently, you can also use the options nocerts/nokeys along with openssl, to extract only one part:

openssl pkcs12 -in myCertificate.pfx -nocerts -out myCertificate.key
openssl pkcs12 -in myCertificate.pfx -nokeys -out myCertificate.pem

1 2	openssl pkcs12 -in myCertificate.pfx -nocerts -out myCertificate.key openssl pkcs12 -in myCertificate.pfx -nokeys -out myCertificate.pem

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Jul 25 / 2018
0

Linux

Automate apt update and keep current config files

When doing update on a Debian/Ubuntu server, if a package is trying to modify a config file, it’s asking for a manual choice. If you’re trying to try to automate the process, you’d probably like to get rid of that ask and keep the current config file by default.

For that, you can use that script:

#!/bin/bash
apt-get update
listUpgrades=`apt list --upgradable |grep upgradable |cut -d/ -f1`
execUpgrades="DEBIAN_FRONTEND=noninteractive apt-get --yes --assume-yes -o DPkg::options::=\"--force-confdef\" -o DPkg::options::=\"--force-confold\" --only-upgrade install "$listUpgrades
eval $execUpgrades

#!/bin/bash

apt-get update

listUpgrades=`apt list --upgradable |grep upgradable |cut -d/ -f1`

execUpgrades="DEBIAN_FRONTEND=noninteractive apt-get --yes --assume-yes -o DPkg::options::=\"--force-confdef\" -o DPkg::options::=\"--force-confold\" --only-upgrade install "$listUpgrades

eval $execUpgrades

The multiple options will enforce the update to keep current config and not overwrite it with the package default one.

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Jun 04 / 2018
0

Linux

Installing Oracle JRE using command line (no repo)

There is no way to easily automate deployment of Oracle JRE since there is no official repository for most of the linux distros. But there’s still a workaround to automatically download the JRE and install it locally on a server by using command lines.

Here is an example of how you can download the JRE 1.8u172 from official website for a CentOS server. You’ll have to grab the URL of the package you want to download from the website http://www.oracle.com/technetwork/java/javase/downloads/jre8-downloads-2133155.html

First, download the package from the website by accepting the license automatically:

wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u172-b11/a58eab1ec242421181065cdc37240b08/jre-8u172-linux-x64.rpm"

1	wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u172-b11/a58eab1ec242421181065cdc37240b08/jre-8u172-linux-x64.rpm"

Then, install the package you downloaded on the server:

sudo yum localinstall jre-8u172-linux-x64.rpm

1	sudo yum localinstall jre-8u172-linux-x64.rpm

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May 25 / 2018
0

Linux

Change the passphrase of your SSH key

Forgot your SSH key passphrase? There’s an easy way to renew it locally if you have access to it:

ssh-keygen -p -f ~/.ssh/id_rsa

1	ssh-keygen -p -f ~/.ssh/id_rsa

And then, enter the new passphrase you want to use.

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Apr 01 / 2018
0

Linux, Python

Using procmail with custom python script

If you want to execute some special commands, log or make an API call when you’re receiving an email onto your server, you can easily set up this by using procmail. Procmail is designed to filter and sort emails but can make any call you want.

Here, as an example, we will set up a simple call to a python script that will read the content of the mail (headers and body) and put the information into a log file.

1. Install procmail

Depending on the OS you’re using, you should find a package pre-compiled in the common repositories.

For example, on a Debian-based:

apt-get install procmail

1	apt-get install procmail

or on a CentOS-based:

yum install procmail

1	yum install procmail

2. Build the python script you want to call to analyze the message

You now have to prepare your script you will execute when receiving an email, that will read and parse the content to log interesting information in a file.

Let’s create a script called procmail_script.py

import os
import time
import email
import sys
import logging.handlers
import base64

# Constants
LOG_FILE_PATH = os.path.expanduser('/opt/mailAnalysis.log')

# Set up a logger
my_logger = logging.getLogger('MyLogger')
my_logger.setLevel(logging.INFO)
handler = logging.handlers.RotatingFileHandler(LOG_FILE_PATH,  maxBytes=500000, backupCount=4,)
formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s",  "%Y-%m-%d %H:%M:%S")
handler.setFormatter(formatter)
my_logger.addHandler(handler)

# Main function
def main():
    try:
        # Get message
        full_msg = sys.stdin.read()
        msg = email.message_from_string(full_msg)

        # Prepare dict containing data
        data = {}

        # Fill dict 
        data['From'],e    = email.Header.decode_header(msg['From'])[0] if msg.has_key('From') else ''
        data['To'],e      = email.Header.decode_header(msg['To'])[0] if msg.has_key('To') else ''
        data['Subject'],e = email.Header.decode_header(msg['Subject'])[0] if msg.has_key('Subject') else ''
        data['Body']      = msg.get_payload()

        # Add information to log
        my_logger.info('From:    ' + data['From'])
        my_logger.info('To:      ' + data['To'])
        my_logger.info('Subject: ' + data['Subject'])
        my_logger.info('Body:    ' + data['Body'])
    except Exception,e:
        my_logger.error('----- ERROR ENCOUNTERED')
        my_logger.error(str(e))
        my_logger.error('----- END OF ERROR')

# Main program
if __name__ == "__main__":
    start_time = time.time()
    my_logger.info('----- START: ' + str(time.time()))
    result = main()
    my_logger.info('----- END: ' + str(time.time()))
    my_logger.info('Elapsed Seconds: ' + str(time.time() - start_time))
    handler.close()
    sys.exit(result)

import os

import time

import email

import sys

import logging.handlers

import base64

# Constants

LOG_FILE_PATH = os.path.expanduser('/opt/mailAnalysis.log')

# Set up a logger

my_logger = logging.getLogger('MyLogger')

my_logger.setLevel(logging.INFO)

handler = logging.handlers.RotatingFileHandler(LOG_FILE_PATH, maxBytes=500000, backupCount=4,)

formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s", "%Y-%m-%d %H:%M:%S")

handler.setFormatter(formatter)

my_logger.addHandler(handler)

# Main function

def main():

try:

# Get message

full_msg = sys.stdin.read()

msg = email.message_from_string(full_msg)

# Prepare dict containing data

data = {}

# Fill dict

data['From'],e = email.Header.decode_header(msg['From'])[0] if msg.has_key('From') else ''

data['To'],e = email.Header.decode_header(msg['To'])[0] if msg.has_key('To') else ''

data['Subject'],e = email.Header.decode_header(msg['Subject'])[0] if msg.has_key('Subject') else ''

data['Body'] = msg.get_payload()

# Add information to log

my_logger.info('From: ' + data['From'])

my_logger.info('To: ' + data['To'])

my_logger.info('Subject: ' + data['Subject'])

my_logger.info('Body: ' + data['Body'])

except Exception,e:

my_logger.error('----- ERROR ENCOUNTERED')

my_logger.error(str(e))

my_logger.error('----- END OF ERROR')

# Main program

if __name__ == "__main__":

start_time = time.time()

my_logger.info('----- START: ' + str(time.time()))

result = main()

my_logger.info('----- END: ' + str(time.time()))

my_logger.info('Elapsed Seconds: ' + str(time.time() - start_time))

handler.close()

sys.exit(result)

3. Configure your user to pass the mail to your script

So that you can pass rules you want to execute when receiving an email, you need to create a file (hidden) called .procmailrc that will take place in the home directory of the user you want to use.

For example, for executing rules when receiving email to [email protected], you will have to put that file into the home dir like /home/mailuser/.procmailrc

LOGFILE=/var/log/procmail.log
VERBOSE=YES

:0:
* ^Subject:.*procmail.*
* ^TO_mailuser@mycompany.(com|net)
{
  :0c
  procmail-dir/

  :0 fw
  | /usr/bin/python /home/mailuser/procmail_script.py

  :0 e
  procmail-failed-dir/
}

LOGFILE=/var/log/procmail.log

VERBOSE=YES

:0:

* ^Subject:.*procmail.*

* ^TO_mailuser@mycompany.(com|net)

{

:0c

procmail-dir/

:0 fw

| /usr/bin/python /home/mailuser/procmail_script.py

:0 e

procmail-failed-dir/

}

This will perform multiple steps:

Check that the mail recipient is [email protected] or [email protected]
Put a copy of the email into the procmail-dir directory
Pass the message to our python script procmail_script.py
Discard the message if the script succeeds (remove from queue) or copy it to procmail-failed-dir if failed (so you can process it later)

4. Prepare an email and perform a testing locally

First, create a sample mail that you will use for testing in a file called procmail_test.txt:

From: me@mycompany.com
To: mailuser@mycompany.com
Subject: This is a procmail testing

Hey there,
I hope this message will be parsed and logged properly as expected.
This is my first test for procmail deployment!

From: me@mycompany.com

To: mailuser@mycompany.com

Subject: This is a procmail testing

Hey there,

I hope this message will be parsed and logged properly as expected.

This is my first test for procmail deployment!

Then, you can test it by executing procmail manually:

procmail VERBOSE=on /home/mailuser/.procmailrc < /home/mailuser/procmail_test.txt

1	procmail VERBOSE=on /home/mailuser/.procmailrc < /home/mailuser/procmail_test.txt

Now, open the file /opt/mailAnalysis.log and you should have something like:

2018-03-31 08:08:45 - INFO - ----- START: 1522570125.06
2018-03-31 08:08:45 - INFO - From:    me@mycompany.com
2018-03-31 08:08:45 - INFO - To:      mailuser@mycompany.com
2018-03-31 08:08:45 - INFO - Subject: This is a procmail testing
2018-03-31 08:08:45 - INFO - Body:    Hey there,
I hope this message will be parsed and logged properly as expected.
This is my first test for procmail deployment!
2018-03-31 08:08:45 - INFO - ----- END: 1522570125.12
2018-03-31 08:08:45 - INFO - Elapsed Seconds: 0.0624470710754

2018-03-31 08:08:45 - INFO - ----- START: 1522570125.06

2018-03-31 08:08:45 - INFO - From: me@mycompany.com

2018-03-31 08:08:45 - INFO - To: mailuser@mycompany.com

2018-03-31 08:08:45 - INFO - Subject: This is a procmail testing

2018-03-31 08:08:45 - INFO - Body: Hey there,

I hope this message will be parsed and logged properly as expected.

This is my first test for procmail deployment!

2018-03-31 08:08:45 - INFO - ----- END: 1522570125.12

2018-03-31 08:08:45 - INFO - Elapsed Seconds: 0.0624470710754

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Home

Fix the NO_PUBKEY error with apt on Ubuntu

Extract certificate and/or key from a PKCS12 file

Automate apt update and keep current config files

Installing Oracle JRE using command line (no repo)

Change the passphrase of your SSH key

Using procmail with custom python script

1. Install procmail

2. Build the python script you want to call to analyze the message

3. Configure your user to pass the mail to your script

4. Prepare an email and perform a testing locally

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