Posts Tagged ‘imap’

Mail send from command line on Linux and *BSD servers – useful for scripting

Monday, September 10th, 2018

mail-send-email-from-command-line-on-linux-and-freebsd-operating-systems-logo

Historically Email sending has been very different from what most people use it in the Office, there was no heavy Email clients such as Outlook Express no MX Exchange, no e-mail client capabilities for Calendar and Meetings schedule as it is in most of the modern corporate offices that depend on products such as Office 365 (I would call it a connectedHell 365 days a year !).

There was no free webmail and pop3 / imap providers such as Mail.Yahoo.com, Gmail.com, Hotmail.com, Yandex.com, RediffMail, Mail.com the innumerous lists goes and on.
Nope back in the day emails were doing what they were originally supposed to like the post services in real life simply send and receive messages.

For those who remember that charming times, people used to be using BBS-es (which were basicly a shared set-up home system as a server) or some of the few University Internal Email student accounts or by crazy sysadmins who received their notification and warnings logs about daemon (services) messages via local DMZ-ed network email servers and it was common to read the email directly with mail (mailx) text command or custom written scripts … It was not uncommon also that mailx was used heavily to send notification messages on triggered events from logs. Oh life was simple and clear back then, and even though today the email could be used in a similar fashion by hard-core old school sysadmins and Dev Ops / simple shell scriptings tasks or report cron jobs such usage is already in the deep history.

The number of ways one could send email in text format directly from the GNU / Linux / *BSD server to another remote mail MTA node (assuming it had properly configured Relay server be it Exim or Postifix) were plenty.

In this article I will try to rewind back some of the UNIX history by pinpointing a few of the most common ways, one used to send quick emails directly from a remote server connection terminal or lets say a cheap VPS few cents server, through something like (SSH or Telnet) etc.
 

1. Using the mail command client (part of bsd-mailx on Debian).
 

In my previous article Linux: "bash mail command not found" error fix
I ended the article with a short explanation on how this is done but I will repeat myself one more time here for the sake of clearness of this article.

root@linux:~# echo "Your Sample Message Body" | mail -s "Whatever … Message Subject" remote_receiver@remote-server-email-address.com


The mail command will connect to local server TCP PORT 25 on local configured MTA and send via it. If the local MTA is misconfigured or it doesn't have a proper MX / PTR DNS records etc. or not configure as a relay SMTP remote mail will not get delivered. Sent Email should be properly delivered at remote recipient address.

How to send HTML formatted emails using mailx command on Linux console / terminal shell using remote server through SSH ?

Connect to remote SSH server (VPS), dedicated server, home Linux router etc. and run:

 

root@linux:~# mailx -a 'Content-Type: text/html'
      -s "This is advanced mailx indeed!" < email_content.html
      "first_email_to_send_to@gmail.com, mail_recipient_2@yahoo.com"

 


email_content.html should be properly formatted (at best w3c standard compliant) HTML.

Here is an example email_content.html (skeleton file)

 

    To: your_customer@gmail.com
    Subject: This is an HTML message
    From: marketing@your_company.com
    Content-Type: text/html; charset="utf8"

    <html>
    <body>
    <div style="
        background-color:
        #abcdef; width: 300px;
        height: 300px;
        ">
    </div>
Whatever text mixed with valid email HTML tags here.
    </body>
    </html>


Above command sends to two email addresses however if you have a text formatted list of recipients you can easily use that file with a bash shell script for loop and send to multiple addresses red from lets say email_addresses_list.txt .

To further advance the one liner you can also want to provide an email attachment, lets say the file email_archive.rar by using the -A email_archive.rar argument.

 

root@linux:~# mailx -a 'Content-Type: text/html'
      -s "This is advanced mailx indeed!" -A ~/email_archive.rar < email_content.html
      "first_email_to_send_to@gmail.com, mail_recipient_2@yahoo.com"

 

For those familiar with Dan Bernstein's Qmail MTA (which even though a bit obsolete is still a Security and Stability Beast across email servers) – mailx command had to be substituted with a custom qmail one in order to be capable to send via qmail MTA daemon.
 

2. Using sendmail command to send email
 

Do you remember that heavy hard to configure MTA monster sendmail ? It was and until this very day is the default Mail Transport Agent for Slackware Linux.

Here is how we were supposed to send mail with it:

 

[root@sendmail-host ~]# vim email_content_to_be_delivered.txt

 

Content of file should be something like:

Subject: This Email is sent from UNIX Terminal Email

Hi this Email was typed in a file and send via sendmail console email client
(part of the sendmail mail server)

It is really fun to go back in the pre-history of Mail Content creation 🙂

 

[root@sendmail-host ~]# sendmail -v user_name@remote-mail-domain.com  < /tmp/email_content_to_be_delivered.txt

 

-v argument provided, will make the communication between the mail server and your mail transfer agent visible.
 

3. Using ssmtp command to send mail
 

ssmtp MTA and its included shell command was used historically as it was pretty straight forward you just launch it on the command line type on one line all your email and subject and ship it (by pressing the CTRL + D key combination).

To give it a try you can do:

 

root@linux:~# apt-get install ssmtp
Reading package lists… Done
Building dependency tree       
Reading state information… Done
The following additional packages will be installed:
  libgnutls-openssl27
The following packages will be REMOVED:
  exim4-base exim4-config exim4-daemon-heavy
The following NEW packages will be installed:
  libgnutls-openssl27 ssmtp
0 upgraded, 2 newly installed, 3 to remove and 1 not upgraded.
Need to get 239 kB of archives.
After this operation, 3,697 kB disk space will be freed.
Do you want to continue? [Y/n] Y
Get:1 http://ftp.us.debian.org/debian stretch/main amd64 ssmtp amd64 2.64-8+b2 [54.2 kB]
Get:2 http://ftp.us.debian.org/debian stretch/main amd64 libgnutls-openssl27 amd64 3.5.8-5+deb9u3 [184 kB]
Fetched 239 kB in 2s (88.5 kB/s)         
Preconfiguring packages …
dpkg: exim4-daemon-heavy: dependency problems, but removing anyway as you requested:
 mailutils depends on default-mta | mail-transport-agent; however:
  Package default-mta is not installed.
  Package mail-transport-agent is not installed.
  Package exim4-daemon-heavy which provides mail-transport-agent is to be removed.

 

(Reading database … 169307 files and directories currently installed.)
Removing exim4-daemon-heavy (4.89-2+deb9u3) …
dpkg: exim4-config: dependency problems, but removing anyway as you requested:
 exim4-base depends on exim4-config (>= 4.82) | exim4-config-2; however:
  Package exim4-config is to be removed.
  Package exim4-config-2 is not installed.
  Package exim4-config which provides exim4-config-2 is to be removed.
 exim4-base depends on exim4-config (>= 4.82) | exim4-config-2; however:
  Package exim4-config is to be removed.
  Package exim4-config-2 is not installed.
  Package exim4-config which provides exim4-config-2 is to be removed.

Removing exim4-config (4.89-2+deb9u3) …
Selecting previously unselected package ssmtp.
(Reading database … 169247 files and directories currently installed.)
Preparing to unpack …/ssmtp_2.64-8+b2_amd64.deb …
Unpacking ssmtp (2.64-8+b2) …
(Reading database … 169268 files and directories currently installed.)
Removing exim4-base (4.89-2+deb9u3) …
Selecting previously unselected package libgnutls-openssl27:amd64.
(Reading database … 169195 files and directories currently installed.)
Preparing to unpack …/libgnutls-openssl27_3.5.8-5+deb9u3_amd64.deb …
Unpacking libgnutls-openssl27:amd64 (3.5.8-5+deb9u3) …
Processing triggers for libc-bin (2.24-11+deb9u3) …
Setting up libgnutls-openssl27:amd64 (3.5.8-5+deb9u3) …
Setting up ssmtp (2.64-8+b2) …
Processing triggers for man-db (2.7.6.1-2) …
Processing triggers for libc-bin (2.24-11+deb9u3) …

 

As you see from above output local default Debian Linux Exim is removed …

Lets send a simple test email …

 

hipo@linux:~# ssmtp user@remote-mail-server.com
Subject: Simply Test SSMTP Email
This Email was send just as a test using SSMTP obscure client
via SMTP server.
^d

 

What is notable about ssmtp is that even though so obsolete today it supports of STARTTLS (email communication encryption) that is done via its config file

 

/etc/ssmtp/ssmtp.conf

 

4. Send Email from terminal using Mutt client
 

Mutt was and still is one of the swiff army of most used console text email clients along with Alpine and Fetchmail to know more about it read here

Mutt supports reading / sending mail from multiple mailboxes and capable of reading IMAP and POP3 mail fetch protocols and was a serious step forward over mailx. Its syntax pretty much resembles mailx cmds.

 

root@linux:~# mutt -s "Test Email" user@example.com < /dev/null

 

Send email including attachment a 15 megabytes MySQL backup of Squirrel Webmail

 

root@linux:~# mutt  -s "This is last backup small sized database" -a /home/backups/backup_db.sql user@remote-mail-server.com < /dev/null

 


5. Using simple telnet to test and send email (verify existence of email on remote SMTP)
 

As a Mail Server SysAdmin this is one of my best ways to test whether I had a server properly configured and even sometimes for the sake of fun I used it as a hack to send my mail 🙂
telnet is and will always be a great tool for doing SMTP issues troubleshooting.
 

It is very useful to test whether a remote SMTP TCP port 25 is opened or a local / remote server firewall prevents connections to MTA.

Below is an example connect and send example using telnet to my local SMTP on pc-freak.net (QMail powered (R) 🙂 )

sending-email-using-telnet-command-howto-screenshot

 

root@pcfreak:~# telnet localhost 25
Trying 127.0.0.1…
Connected to localhost.
Escape character is '^]'.
220 This is Mail Pc-Freak.NET ESMTP
HELO mail.pc-freak.net
250 This is Mail Pc-Freak.NET
MAIL FROM:<hipo@pc-freak.net>
250 ok
RCPT TO:<roots_bg@yahoo.com>
250 ok
DATA
354 go ahead
Subject: This is a test subject

 

This is just a test mail send through telnet
.
250 ok 1536440787 qp 28058
^]
telnet>

 

Note that the returned messages are native to qmail, a postfix would return a slightly different content, here is another test example to remote SMTP running sendmail or postfix.

 

root@pcfreak:~# telnet mail.servername.com 25
Trying 127.0.0.1…
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
220 mail.servername.com ESMTP Sendmail 8.13.8/8.13.8; Tue, 22 Oct 2013 05:05:59 -0400
HELO yahoo.com
250 mail.servername.com Hello mail.servername.com [127.0.0.1], pleased to meet you
mail from: systemexec@gmail.com
250 2.1.0 hipo@pc-freak.net… Sender ok
rcpt to: hip0d@yandex.ru
250 2.1.5 hip0d@yandex.ru… Recipient ok
data
354 Enter mail, end with "." on a line by itself
Hey
This is test email only

 

Thanks
.
250 2.0.0 r9M95xgc014513 Message accepted for delivery
quit
221 2.0.0 mail.servername.com closing connection
Connection closed by foreign host.


It is handy if you want to know whether remote MTA server has a certain Emailbox existing or not with telnet by simply trying to send to a certian email and checking the Email server returned output (note that the message returned depends on the remote MTA version and many qmails are configured to not give information on the initial SMTP handshake but returns instead a MAILER DAEMON failure error sent back to your sender address. Some MX servrers are still vulnerable to this attack yet, historically dreamhost.com. Below attack screenshot is made at the times before dreamhost.com fixed the brute force email issue.

Terminal-Verify-existing-Email-with-telnet

6. Using simple netcat TCP/IP Swiss Army Knife to test and send email in console

netcat-logo-a-swiff-army-knife-of-the-hacker-and-security-expert-logo
Other tool besides telnet of testing remote / local SMTP is netcat tool (for reading and writting data across TCP and UDP connections).

The way to do it is analogous but since netcat is not present on most Linux OSes by default you need to install it through the package manager first be it apt or yum etc.

# apt-get –yes install netcat


 

First lets create a new file test_email_content.txt using bash's echo cmd.
 

 

# echo 'EHLO hostname
MAIL FROM: hip0d@yandex.ru
RCPT TO:   solutions@pc-freak.net
DATA
From: A tester <hip0d@yandex.ru>
To:   <solutions@pc-freak.net>
Date: date
Subject: A test message from test hostname

 

Delete me, please
.
QUIT
' >>test_email_content.txt

 

# netcat -C localhost 25 < test_email_content.txt

 

220 This is Mail Pc-Freak.NET ESMTP
250-This is Mail Pc-Freak.NET
250-STARTTLS
250-SIZE 80000000
250-PIPELINING
250 8BITMIME
250 ok
250 ok
354 go ahead
451 See http://pobox.com/~djb/docs/smtplf.html.

Because of its simplicity and the fact it has a bit more capabilities in reading / writing data over network it was no surprise it was among the favorite tools not only of crackers and penetration testers but also a precious debug tool for the avarage sysadmin. netcat's advantage over telnet is you can push-pull over the remote SMTP port (25) a non-interactive input.


7. Using openssl to connect and send email via encrypted channel

 

root@linux:~# openssl s_client -connect smtp.gmail.com:465 -crlf -ign_eof

    ===
               Certificate negotiation output from openssl command goes here
        ===

        220 smtp.gmail.com ESMTP j92sm925556edd.81 – gsmtp
            EHLO localhost
        250-smtp.gmail.com at your service, [78.139.22.28]
        250-SIZE 35882577
        250-8BITMIME
        250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
        250-ENHANCEDSTATUSCODES
        250-PIPELINING
        250-CHUNKING
        250 SMTPUTF8
            AUTH PLAIN *passwordhash*
        235 2.7.0 Accepted
            MAIL FROM: <hipo@pcfreak.org>
        250 2.1.0 OK j92sm925556edd.81 – gsmtp
            rcpt to: <systemexec@gmail.com>
        250 2.1.5 OK j92sm925556edd.81 – gsmtp
            DATA
        354  Go ahead j92sm925556edd.81 – gsmtp
            Subject: This is openssl mailing

            Hello nice user
            .
        250 2.0.0 OK 1339757532 m46sm11546481eeh.9
            quit
        221 2.0.0 closing connection m46sm11546481eeh.9
        read:errno=0


8. Using CURL (URL transfer) tool to send SSL / TLS secured crypted channel emails via Gmail / Yahoo servers and MailGun Mail send API service


Using curl webpage downloading advanced tool for managing email send might be  a shocking news to many as it is idea is to just transfer data from a server.
curl is mostly used in conjunction with PHP website scripts for the reason it has a Native PHP implementation and many PHP based websites widely use it for download / upload of user data.
Interestingly besides support for HTTP and FTP it has support for POP3 and SMTP email protocols as well
If you don't have it installed on your server and you want to give it a try, install it first with apt:
 

root@linux:~# apt-get install curl

 


To learn more about curl capabilities make sure you check cURL –manual arg.
 

root@linux:~# curl –manual

 

a) Sending Emails via Gmail and other Mail Public services

Curl is capable to send emails from terminal using Gmail and Yahoo Mail services, if you want to give that a try.

gmail-settings-google-allow-less-secure-apps-sign-in-to-google-screenshot

Go to myaccount.google.com URL and login from the web interface choose Sign in And Security choose Allow less Secure Apps to be -> ON and turn on access for less secure apps in Gmail. Though I have not tested it myself so far with Yahoo! Mail, I suppose it should have a similar security settings somewhere.

Here is how to use curl to send email via Gmail.

Gmail-password-Allow-less-secure-apps-ON-screenshot-howto-to-be-able-to-send-email-with-text-commands-with-encryption-and-outlook

 

 

root@linux:~# curl –url 'smtps://smtp.gmail.com:465' –ssl-reqd \
  –mail-from 'your_email@gmail.com' –mail-rcpt 'remote_recipient@mail.com' \
  –upload-file mail.txt –user 'your_email@gmail.com:your_accout_password'


b) Sending Emails using Mailgun.com (Transactional Email Service API for developers)

To use Mailgun to script sending automated emails go to Mailgun.com and create account and generate new API key.

Then use curl in a similar way like below example:

 

curl -sv –user 'api:key-7e55d003b…f79accd31a' \
    https://api.mailgun.net/v3/sandbox21a78f824…3eb160ebc79.mailgun.org/messages \
    -F from='Excited User <developer@yourcompany.com>' \
    -F to=sandbox21a78f824…3eb160ebc79.mailgun.org \
    -F to=user_acc@gmail.com \
    -F subject='Hello' \
    -F text='Testing Mailgun service!' \
   –form-string html='<h1>EDMdesigner Blog</h1><br /><cite>This tutorial helps me understand email sending from Linux console</cite>' \
    -F attachment=@logo_picture.jpg

 

The -F option that is heavy present in above command lets curl (Emulate a form filled in button in which user has pressed the submit button).
For more info of the options check out man curl.
 

 

9. Using swaks command to send emails from

 

root@linux:~# apt-cache show swaks|grep "Description" -B 10
Package: swaks
Version: 20170101.0-1
Installed-Size: 221
Maintainer: Andreas Metzler <ametzler@debian.org>
Architecture: all
Depends: perl
Recommends: libnet-dns-perl, libnet-ssleay-perl
Suggests: perl-doc, libauthen-sasl-perl, libauthen-ntlm-perl
Description-en: SMTP command-line test tool
 swaks (Swiss Army Knife SMTP) is a command-line tool written in Perl
 for testing SMTP setups; it supports STARTTLS and SMTP AUTH (PLAIN,
 LOGIN, CRAM-MD5, SPA, and DIGEST-MD5). swaks allows one to stop the
 SMTP dialog at any stage, e.g to check RCPT TO: without actually
 sending a mail.
 .
 If you are spending too much time iterating "telnet foo.example 25"
 swaks is for you.
Description-md5: f44c6c864f0f0cb3896aa932ce2bdaa8

 

 

 

root@linux:~# apt-get instal –yes swaks

root@linux:~# swaks –to mailbox@example.com -s smtp.gmail.com:587
      -tls -au <user-account> -ap <account-password>

 


The -tls argument (in order to use gmail encrypted TLS channel on port 587)

If you want to hide the password not to provide the password from command line so (in order not to log it to user history) add the -a options.

10. Using qmail-inject on Qmail mail servers to send simple emails

Create new file with content like:
 

root@qmail:~# vim email_file_content.text
To: user@mail-example.com
Subject: Test


This is a test message.
 

root@qmail:~# cat email_file_content.text | /var/qmail/bin/qmail-inject


qmail-inject is part of ordinary qmail installation so it is very simple it even doesn't return error codes it just ships what ever given as content to remote MTA.
If the linux host where you invoke it has a properly configured qmail installation the email will get immediately delivered. The advantage of qmail-inject over the other ones is it is really lightweight and will deliver the simple message more quickly than the the prior heavy tools but again it is more a Mail Delivery Agent (MDA) for quick debugging, if MTA is not working, than for daily email writting.

It is very useful to simply test whether email send works properly without sending any email content by (I used qmail-inject to test local email delivery works like so).
 

root@linux:~# echo 'To: mailbox_acc@mail-server.com' | /var/qmail/bin/qmail-inject

 

11. Debugging why Email send with text tool is not being send properly to remote recipient

If you use some of the above described methods and email is not delivered to remote recipient email addresses check /var/log/mail.log (for a general email log and postfix MTAs – the log is present on many of the Linux distributions) and /var/log/messages or /var/log/qmal (on Qmail installations) /var/log/exim4 (on servers running Exim as MTA).

http://pc-freak.net/images/linux-email-log-debug-var-log-mail-output

 Closure

The ways to send email via Linux terminal are properly innumerous as there are plenty of scripted tools in various programming languages, I am sure in this article,  also missing a lot of pre-bundled installable distro packages. If you know other interesting ways / tools to send via terminal I would like to hear it.

Hope you enjoyed, happy mailing !

Fix Squirrelmail UTF-8 and windows-1251 Bulgarian encoding problem

Monday, September 8th, 2014

squirrelmail_webmail_for_nuts_fix_bulgarian_reply_encoding_problem-howto
I'm using Squirrelmail (with OutLook skin theme) as a webmail client for my home running Qmail mail server and few other squirrelmail plugins, generally I'm quite happy with Squirrelmail as it perfectly serves me as a web IMAP client the only issue I have is when I'm replying to messages which are written Cyrillic UTF-8 or Cyrillic windows cp-1251 encoding (Bulgarian letters) – I guess Russians which are using squirrelmail with KOI-8R encoding also probably face some similar mail encoding issues. That's pretty annoying because the person message which I'm Replying to gets scrapped and old content becomes unreadable so old correspondence gets broken, because the encoding in which the message is replied is in non-utf-8 encoding ISO-8859, you see example of what I mean in below screenshot:

Fix_solve_Squirrelmail_UTF-8_and_windows-1251_Bulgarian_Russian_encoding_problem_screenshot

So here is how to fix that:
Solution is to convert the Bulgarian translation from windows-1251 to UTF-8 in squirremail.po:
 

find . -iname squirrelmail.po
./themes/squirreloutlook-1.0.3/locale/pt_BR/LC_MESSAGES/squirrelmail.po

cd themes/squirreloutlook-1.0.3/locale/pt_BR/LC_MESSAGES/
iconv -f CP1251 -t UTF-8 squirrelmail.po > squirrelmail.utf-8.po
sed 's/cp1251/UTF-8/' squirrelmail.utf-8.po > squirrelmail.po
rm squirrelmail.utf-8.po
msgfmt -o squirrelmail.mo squirrelmail.po
cd ../../../../../


For Squirrelmail version 1.4

find . -iname i18n.php
./functions/i18n.php
./themes/squirreloutlook-1.0.3/functions/i18n.php

vim ./themes/squirreloutlook-1.0.3/functions/i18n.php
vim functions/i18n.php


Paste below, the commented section about Bulgarian Language (//) (below configuration):

 

$languages[‘bg_BG’][‘NAME’] = 'Bulgarian';
$languages[‘bg_BG’][‘CHARSET’] = 'utf-8';
$languages[‘bg_BG’][‘LOCALE’] = 'bg_BG.UTF-8';
$languages[‘bg’][‘ALIAS’] = 'bg_BG';

 

 


For Squirrelmail version 1.5


locale/bg_BG/setup.php
 

Finally to make new Squirrelmail configuration affective restart Apache Webserver

 

/etc/init.d/apache2 restart


Fixing issues with broken (Russian) cyrillic KOI8-R encoding in reply mail in squirrelmail should be analogical.

 

 

 

Fixing insserv: warning: script ‘…’ missing LSB tags and overrides on Debian and Ubuntu Linux

Friday, April 12th, 2013

apt-get f install logo fixing warning script missing LSB tags Debian Ubuntu Linux
 

Some of packages I just tried to install on one of the Debian servers I admin failed during package (set up) configuration stage. Here is little paste with the errors due to it dpkg-reconfigure on each of newly set-up packages failed:

Setting up acct (6.5.4-2.1) ...
insserv: warning: script 'K02courier-imap' missing LSB tags and overrides
insserv: warning: script 'courier-imapd' missing LSB tags and overrides
insserv: warning: script 'iptables' missing LSB tags and overrides
insserv: warning: script 'courier-imap' missing LSB tags and overrides 

Because of this whole package install failed and the usual

# apt-get -f install

supposed to fix mess with packages end up with same errors:

insserv: warning: script 'K02courier-imap' missing LSB tags and overrides
insserv: warning: script 'iptables' missing LSB tags and overrides
insserv: warning: script 'courier-imap' missing LSB tags and overrides
insserv: There is a loop between service watchdog and iptables if stopped
insserv:  loop involving service iptables at depth 2
insserv:  loop involving service watchdog at depth 1
insserv: Stopping iptables depends on watchdog and therefore on system facility `$all' which can not be true!
insserv: exiting now without changing boot order!
update-rc.d: error: insserv rejected the script header
dpkg: error processing acct (--configure):
 subprocess installed post-installation script returned error exit status 1

T
he scripts in question iptables / courier-imap / K02courier-imap were custom created  scripts by me earlier and I have completely forgot about it. In Debian 5 and earlier I used the same scripts to make system load custom services not installed through a standard Debian package. After a bit of research, I've noticed in newer Debian / Ubuntu release, new Commented tags are included in all Debian belonging packages init scripts. Thus the reason for failing package configuration, were my custom scripts were missing those tags. To get around the situation I had to open manually each of the scripts missing init script LSB tags i.e. ( iptables / courier-imap / K02courier-imap ) and add after
#! /bin/sh

shebang;

### BEGIN INIT INFO
# Provides:          skeleton
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Example initscript
# Description:       This file should be used to construct scripts to be
#                    placed in /etc/init.d.
### END INIT INFO

Once those "boilerplate", skele comments are included to solve the mess I had to run again:

# apt-get -f install

This solves it. Enjoy 🙂


Easy way to look for irregularities and problems in log files / Facilitate reading log files on GNU / Linux and FreeBSD

Thursday, November 24th, 2011

LogWatch logo picture check Logcheck Linux BSD look for irregularities in log files

As a System Administrator I need to check daily the log files produced on various GNU / Linux distributions or FreeBSD. This can sometimes take too much time if the old fashioned way using the normal system tools cat, less and tail etc. is used.

Reading logs one by one eats too much of my time and often as logs are reviewed in a hurry some crucial system irregularities, failed ssh or POP3 / Imap logins, filling disk spaces etc. are missed.

Therefore I decided to implement automated log parsing programs which will summary and give me an overview (helicopter view) on what were the system activities from the previous day (24h) until the moment I logged the system and issued the log analyzer program.
There are plenty of programs available out there that does “wide scale” log analysis, however there are two applications which on most GNU / Linux and BSD systems had become a de-facto standard programs to scan system log files for interesting lines.

These are:
 

  • 1. logwatchsystem log analyzer and reporter
  • 2. logcheckprogram to scan system log files for interesting lines

1. logwatch is by default installed on most of the Redhat based Linux systems (Fedora, RHEL, CentOS etc.). On Debian distributions and as far as I know (Ubuntu) and the other deb based distros logwatch is not installed by default. Most of the servers I manage these days are running Debian GNU / Linux so, to use logwatch I needed to install it from the available repository package, e.g.:

debian:~# apt-get install logwatch
...

logwatch is written in perl and with some big files to analyze, parsing them might take hell a lot of time. It does use a bunch of configuration scripts which defines how logwatch should read and parse the various services logwatch support by default. These conf scripts are also easily extensible, so if one has to analyze some undefined service in the conf files he can easily come up with a new conf script that will support the service/daemon of choice.Using logwatch is very easy, to get an overview about server system activity invoke the logwatch command:

debian:~# logwatch
################### Logwatch 7.3.6+cvs20080702-debian (07/02/08) ####################
Processing Initiated: Thu Nov 24 05:22:07 2011
Date Range Processed: yesterday
( 2011-Nov-23 )
Period is day.
Detail Level of Output: 0
Type of Output/Format: stdout / text
Logfiles for Host: debian
 ################################################# 

——————— dpkg status changes Begin ————- 

Upgraded:
libfreetype6 2.3.7-2+lenny7 => 2.3.7-2+lenny8
libfreetype6-dev 2.3.7-2+lenny7 => 2.3.7-2+lenny8

———————- dpkg status changes End ————————-

——————— httpd Begin ————————

Requests with error response codes
400 Bad Request
HTTP/1.1: 2 Time(s)
admin/scripts/setup.php: 2 Time(s)
401 Unauthorized


———————- vpopmail End ————————-

——————— Disk Space Begin ————————

Filesystem Size Used Avail Use% Mounted on
/dev/md0 222G 58G 154G 28% /

———————- Disk Space End ————————-

###################### Logwatch End #########################

The execution might take up from 10 to 20 seconds up to 10 or 20 minutes depending on the log files size and the CPU / RAM hardware on the machine where /var/log/… logs will be analyzed.

logwatch output can be easily mailed to a custom mail address using a crontab if the server runs a properly configured SMTP server. Using a cron like:

00 5 * * * /usr/sbin/logwatch | mail -s "$(hostname) log files for $(date)"

Here is time to make a note that logwatch is ported also to FreeBSD and is available from BSD’s port tree, from a port with path:

/usr/ports/security/logcheck

2. logcheck is another handy program, which does very similar job to logwatch . The “interesting” information it returns is a bit less than compared to logwatch

The good thing about logcheck is that by default it is made to mail every 1 hour a brief data summary which might be of an interest to the sys admin.
Logcheck is available for install on RedHat distros via yum and has existing package for Debian as well as a port for FreeBSD under the port location /usr/ports/security/logcheck

To install on logcheck on Debian:

debian:~# apt-get install logcheck
...

After installation I found it wise to change the default mailing time from each and every hour to just once per day to prevent my email from overfilling with “useless” mails.

This is done by editting the default cron tab installed by the package located in /etc/cron.d/logcheck

The default file looks like so:

# /etc/cron.d/logcheck: crontab entries for the logcheck package
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
@reboot logcheck if [ -x /usr/sbin/logcheck ]; then nice -n10 /usr/sbin/logcheck -R; fi
2 * * * * logcheck if [ -x /usr/sbin/logcheck ]; then nice -n10 /usr/sbin/logcheck; fi
# EOF

To change it run only once per day its content should looks something like:

# /etc/cron.d/logcheck: crontab entries for the logcheck package
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
@reboot logcheck if [ -x /usr/sbin/logcheck ]; then nice -n10 /usr/sbin/logcheck -R; fi
2 5 * * * logcheck if [ -x /usr/sbin/logcheck ]; then nice -n10 /usr/sbin/logcheck; fi
# EOF

Altering it that way the log summary interesting info analysis will be sent on mail every day in 05:02 a.m.
Changing the default email logcheck will ship its log analyzer report emails on deb based distros is done via editting the file:

/etc/logcheck/logcheck.conf

And changing the SENDMAILTO=”” variable to point to the appropriate admin email email addr.
 

How to test if imap and pop mail server service is working with Telnet cmd

Monday, August 8th, 2011

test-if-imap-pop3-is-working-with-telnet-command-logo-imap
I’ve recently built new mail qmail server with vpopmail to serve pop3 connectins and courierimap and courierimaps to take care for IMAP IMAPS.

I further used telnet to test if the Linux server pop3 service on (110) and imap on (143) worked fine, straight after the completed qmail install.
Here is how to test mail server with vpopmail listening for connections on pop3 port :

debian:~# telnet mail.mymailserver.com 110
Trying 111.222.333.444...
Connected to mail.mymailserver.com.
Escape character is '^]'.
+OK <2813.1312745988@mymailserver.com>
USER hipo@mymailserver.com
+OK
PASS here_goes_my_secret_pass
+OK
LIST
1 309783
2 64053
3 2119
4 64357
5 317893
RETR 1
My first mail content retrieved with RETR commandgoes here ....
quit
+OK
Connection closed by foreign host.

You see I have 5 messages in my mailbox, as you can see I used RETR command to check the content of my mail, this is handy as I can read my mails straight with telnet (if the mail is in plain text), of course it’s a bit more complicated if I have to read encrypted or html mail, though still its easy to write a tiny parser and pipe the content produced by telnet command to lynx or some other text based browser.

Now another sys admin handy tip is the use of telnet to check my mail servers IMAP servers is correctly operating.
Here is how:

debian:~# telnet mail.mymailserver.com 143
Trying 111.222.333.444...
Connected to localhost.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2010 Double Precision, Inc. See COPYING for distribution information.
01 LOGIN hipo@mymailserver.com here_goes_my_secret_pass
A OK LOGIN Ok.
02 LIST "" *
* LIST (Unmarked HasNoChildren) "." "INBOX"
02 OK LIST completed
03 SELECT INBOX
* FLAGS (Draft Answered Flagged Deleted Seen Recent)
* OK [PERMANENTFLAGS (* Draft Answered Flagged Deleted Seen)] Limited
* 5 EXISTS
* 5 RECENT
* OK [UIDVALIDITY 1312746907] Ok
* OK [MYRIGHTS "acdilrsw"] ACL
03 OK [READ-WRITE] Ok
04 STATUS INBOX (MESSAGES)
* STATUS "INBOX" (MESSAGES 5)
04 OK STATUS Completed.
05 FETCH 1 ALL
...
06 FETCH 1 BODY
...
07 FETCH 1 ENVELOPE
...
As you can see according to standard to send commands to IMAP server from console after a telnet connection you will have to always include a command line number like 01, 02, 03 .. etc.

Using such a line numbering is not obligitory and also letters like A, B, C could be use still line numbering with numbers is generally a good idea since it’s easier for reading on the screen.

Now line 02 shows you available mailboxes, line 03 SELECT INBOX selects the imap Inbox to be further operated with, 04 STATUS INBOX cmd displays status about current mailboxes in folder.
FETCH 1 ALL instructs the imap server to get list of all IMAP message headers. Next command in line 05 FETCH 1 BODY will display the message body of the first message in list.
The 07 FETCH 1 ENVELOPE will display the mail headers for the 1 message.

Few other IMAP commands which might be helpfun on connection are:

08 FETCH 1 FULL
09 FETCH * FULL

First one would fetch complete content of a message numbered one from the imap server and the second one 09 FETCH * FULL will get all the mail content for all messages located on the remote IMAP server.

The STATUS command aforementioned earlier could take the following list of arguments:

MESSAGES, UNSEEN, RECENT UIDNEXT UIDVALIDITY

These commands are a gold mine for me as a sysadmin as it helps quickly solve problems, hope they would help to somebody out there as well 😉
This way is a way shorter than bothering each time to check, if some customer e-mail account is improperly configured by creating setting up a new account in Thunderbird.
 

How to check if newly installed SSL certificate for IMAP and IMAPS is properly installed

Tuesday, June 28th, 2011

Did you have to regenerate your SSL certificate for your mail server’s IMAP and IMAP SSL service?
Did you have to find out if the newly installed certificates are fine after install?

Here is how:

          root@server-hosting [/usr/local ]# openssl s_client -connect imap.example.com:993
root@server-hosting [/usr/local ]# openssl s_client -connect imap.example.com:143 -starttls imap

The output returned by this two commands will be the imap and imaps configured certificates as well as extensive info concerning the installed SSL, the last chunk of info to be spit is most crucial to know if certificate is fine.
It should be something like:

...
New, TLSv1/SSLv3, Cipher is AES256-SHA
Server public key is 1024 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
Protocol : TLSv1
Cipher : AES256-SHA
Session-ID: 0B69E91022CB56D64F56CFA08405944D9C4C0069EE4097890B98F1406CF084D5
Session-ID-ctx:
Master-Key: 13745B94E0C5A0604EB7529E7409251961DFD5F4134F3A8F
Key-Arg : None
Start Time: 1309265383
Timeout : 300 (sec)
Verify return code: 18 (self signed certificate)
---
. OK CAPABILITY completed
closed

How to configure pine (alpine) console client to work with vpopmail pop3 and imap protocol

Monday, June 13th, 2011

I needed to check my mail via ssh connection, as my installed squirrelmail is curently broken and I’m away from my own personal computer.

I did some online research on how this can be achieved and thanksfully I finallyfound a way to check my pop3 and imap mailbox with a console client called alpine , better known in unix community under the name pine .

I installed pine on my Debian with apt:


debian:~# apt-get install alpine

Here is my pine configuration file .pinerc used to fetch my mail with pine:

a .pinerc conf file to check my pop3 mail

To use that file I placed it in my home directory ~/ , e.g.:


debian:~# wget http://www.pc-freak.net/files/.pinerc
...

To attune the pop3 server configuration in the sample .pinerc above one needs to change the value of:


inbox-path=

For example to configure pine to fetch mail from the pop3 server mail.pc-freak.net and store it locally in my home directory within a file called INBOX
I have configured the inbox-path .pinerc variable to look like so:


inbox-path={mail.pc-freak.net/pop3/user=hipo@pc-freak.net}INBOX

In above configuration’s inbox-path variable configuration the /pop3/ specifies I want to fetch my mail via the pop3 protocol , if one wants to use imap this has to be substituted with /imap/

The value user=hipo@pc-freak.net specifies my vpopmail created user which in my case is obviously hipo@pc-freak.net

The other variables which are good to be changed in .pinerc config are:


personal-name=

This variable has to be set to the name of the Email Sender which will be set, if pine is used to send email.

I also changed the user-domain variable as it’s used to set the domain name from which the pine client will send the emails from:

As my domain is pc-freak.net I’ve set the domain name variable to be:


user-domain=pc-freak.net

Now after launching pine it prompted me for my email password, putting in the pass did fetch all my new unread mails via pop3 protocol.

The only annoying thing was that each time I quit pine and start it up again, I’m now asked to enter the email password.

This behaviour is really shitty, but thanksfully one can easily workaround that by letting pine be constantly running detached in gni screen session.