install certbot on ubuntu 16.04

On Ubuntu systems, the Certbot team maintains a PPA. Once you add it to your list of repositories all you’ll need to do is apt-get the following packages.

$ sudo apt-get update
$ sudo apt-get install software-properties-common
$ sudo add-apt-repository ppa:certbot/certbot
$ sudo apt-get update
$ sudo apt-get install python-certbot-apache


protect zimbra from memcached attack

Zimbra uses memcached and if not properly configured could lead to a vulnerable system.

If you want to read more on memcached attack read this:

How to resolve this vulnerability in 3 steps:

  1. Enable firewall on your server
  2. Setup zimbra specific rules
  3. Bind memcached to localhost
  4. Deny memcached port from localhost

Let’s start.

Continue reading “protect zimbra from memcached attack”

remove banned ip from microsoft ban lists

This works for,, and possibly other microsoft related email addresses.

Use this form to request removal:

Make sure you ‘re registered:

This was an old one and does not seem to work anymore:


osticket and self-signed-certificates on email server

This has to do with PHP >= 5.6, where php changed its behavior with self signed certificates.  This has caused osticket users to keep old PHP versions in order to operate with self signed mail servers. But actually the fix is relatively simple:
Go to {osTicket directory}/include/pear/Net/SMTP.php line 173 and change this line:

‘ssl’ => array(‘verify_peer_name’ => false)
to this
‘ssl’ => array(‘verify_peer’ => false, ‘verify_peer_name’ => false)
This was copied from
(see KevinTheJedi answer on 2017 February 17)
I copy the original response below:

Do you have a test environment that is getting this issue with PHP 5.6 and osTicket 1.10?

If so try something for me to see if your issue goes away (I am unable to replicate this error):

1.) Go to {osTicket directory}/include/pear/Net/SMTP.php line 173 and change this line:

‘ssl’ => array(‘verify_peer_name’ => false)
to this
‘ssl’ => array(‘verify_peer’ => false, ‘verify_peer_name’ => false)

2.)Go to {osTicket directory}/include/pear/Mail/smtp.php line 141 and change this line:
$timeout = null;
to this
$timeout = 60;

rsync including hidden files and differences with scp

rsync -av --progress src/ [email protected]:dest/

scp should also do the job but rsync is better

scp -rp src [email protected]:dest/

Nice explanation about the differences can be found here:

scp basically reads the source file and writes it to the destination. It performs a plain linear copy, locally, or over a network.

rsync also copies files locally or over a network. But it employs a special delta transfer algorithm and a few optimizations to make the operation a lot faster. Consider the call.

rsync A host:B
rsync will check files sizes and modification timestamps of both A and B, and skip any further processing if they match.
If the destination file B already exists, the delta transfer algorithm will make sure only differences between A and B are sent over the wire.
rsync will write data to a temporary file T, and then replace the destination file B with T to make the update look “atomic” to processes that might be using B.
Anther difference between them concerns invocation. rsync has a plethora of command line options, allowing the user to fine tune its behavior. It supports complex filter rules, runs in batch mode, daemon mode, etc. scp has only a few switches.

In summary, use scp for your day to day tasks. Commands that you type once in a while on your interactive shell. Its simpler to use, and in those cases rsync optimizations won’t help much.

For recurring tasks, like cron jobs, use rsync. As mentioned, on multiple invocations it will take advantage of data already transferred, performing very quickly and saving on resources. It is an excellent tool to keep two directories synchronized over a network.

Also, when dealing with large files, use rsync with the -P option. If the transfer is interrupted, you can resume it where it stopped by reissuing the command.

how to install erpnext on ubuntu

This guide is based on, and is tested a couple of times against ubuntu 14.04/64.

      • Login as root with ssh.
      • Optionally:
        apt-get update
        apt-get upgrade
        dpkg-reconfigure tzdata
        apt-get install nano
      • Add a user (erpnext for our example).
adduser erpnext

Store password in a safe place for later use.

      • visudo (to grant erpnext user sudo privileges, by copying root record)

A nice article on user management:

  • Login as erpnext.
    su erpnext
  • Download script at home dir and execute it.
cd ~
sudo python --production --user erpnext

You will prompted for mysql and admin passwords.
Store both passwords in a safe place for later use.

The script is going to take some moments to complete depending on hardware, let’s say 5 or 10 minutes.

  • Restart web server, sudo service nginx restart.
  • Fire up your browser and point to your server’s IP (or hostname). If everything goes well you will see eprnext login screen. Use your stored admin pass to access web app. Eventually a nice setup wizard will show up at your browser.

You’re amost done. To increase security you should install ssl. We’ll use let’s encrypt for our example.

    • su erpnext
    • cd ~
    • cd frappe-bench
    • Important! Assuming your domain is mv sites/site1.local sites/
    • nano sites/
    • Add "host_name": "",

Don’t forget commas separating json records.

  • Enable dns multitenancy: bench config dns_multitenant on
  • Regenerate nginx config: bench setup nginx
  • Reload nginx: sudo service nginx reload
  • Configure let’s encrypt: sudo -H bench setup lets-encrypt

If errors occur, recheck all your steps. If https/ssl still fails, try the manual method below.

  • su root
  • cd /opt
  • wget
  • sudo service nginx stop
  • ./opt/certbot-auto certonly --standalone
  • su erpnext
  • cd ~/frappe-bench/sites/
  • nano sites/
  • Add two lines, beware of the commas separating json records! "ssl_certificate": "/etc/letsencrypt/live/",
    "ssl_certificate_key": "/etc/letsencrypt/live/"
    , save and exit nano
  • bench setup nginx, to regenerate cofig files.
  • sudo service nginx restart

Now, you should be ok with letsencrypt cert. Letsencrypt certificate expires every three months, so you’d better set up a cronjob that automatically renew certificate. It should be as easy as adding a crontab entry.

  • crontab -e
  • Add this: # renew letsencrypt certificates on 1st monday of every month and get an email if it gets executed
    MAILTO="[email protected]"
    0 0 1-7 * * [ "$(date '+\%a')" = "Mon" ] && sudo service nginx stop && /opt/certbot-auto renew && sudo service nginx start

You’re done.


Official frappe documentation provides an article for https/ssl:

If you want to install a second site on the same server see this:

how to add a second erpnext instance on ubuntu