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How to monitor Postfix Mail server work correct with simple one liner Zabbix user parameter script / Simple way to capture and report SMTP machine issues Zabbix template

Thursday, June 22nd, 2023

setup-zabbix-smtp-mail-monitoring-postfix-qmail-exim-with-easy-userparameter-script-and-template-zabbix-logo

In this article, I'm going to show you how to setup a very simple monitoring if a local running SMTP (Postfix / Qmail / Exim) is responding correctly on basic commands. The check would helpfully keep you in track to know whether your configured Linux server local MTA (Mail Transport Agent) is responding on requests on TCP / IP protocol Port 25, as well as a check for process existence of master (that is the main postfix) proccess, as well as the usual postfix spawned sub-processes qmgr (the postfix queue manager), tsl mgr (TLS session cache and PRNG manager), pickup (Postfix local mail pickup) – or email receiving process.

 

Normally a properly configured postfix installation on a Linux whatever you like distribution would look something like below:

#  ps -ef|grep -Ei 'master|postfix'|grep -v grep
root        1959       1  0 Jun21 ?        00:00:00 /usr/libexec/postfix/master -w
postfix     1961    1959  0 Jun21 ?        00:00:00 qmgr -l -t unix -u
postfix     4542    1959  0 Jun21 ?        00:00:00 tlsmgr -l -t unix -u
postfix  2910288    1959  0 11:28 ?        00:00:00 pickup -l -t unix -u

At times, during mail server restarts the amount of processes that are sub spawned by postfix, may very and if you a do a postfix restart

# systemctl restart postfix

The amout of spawned processes running as postfix username might decrease, and only qmgr might be available for second thus in the consequential shown Template the zabbix processes check to make sure the Postfix is properly operational on the Linux machine is made to check for the absolute minumum of 

1. master (postfix process) that runs with uid root
2. and one (postfix) username binded proccess 

If the amount of processes on the host is less than this minimum number and the netcat is unable to simulate a "half-mail" sent, the configured Postfix alarm Action (media and Email) will take place, and you will get immediately notified, that the monitored Mail server has issue!

The idea is to use a small one liner connection with netcat and half simulate a normal SMTP transaction just like you would normally do:

 

root@pcfrxen:/root # telnet localhost 25
Trying 127.0.0.1…
Connected to localhost.
Escape character is '^]'.
220 This is Mail2 Pc-Freak.NET ESMTP
HELO localhost
250 This is Mail2 Pc-Freak.NET
MAIL FROM:<hipopo@pc-freak.net>
250 ok
RCPT TO:<hip0d@remote-smtp-server.com>
 

and then disconnect the connection.

1. Create new zabbix userparameter_smtp_check.conf file

The simple userparameter one liner script to do the task looks like this:

# vi /etc/zabbix/zabbix_agent.d/userparameter_smtp_check.conf

UserParameter=smtp.check,(if [[ $(echo -e “HELO localhost\n MAIL FROM: root@$HOSTNAME\n RCPT TO: report-email@your-desired-mail-server.com\n  QUIT\n” | /usr/bin/nc localhost 25 -w 5 2>&1 | grep -Ei ‘220\s.*\sESMTP\sPostfix|250\s\.*|250\s\.*\sOk|250\s\.*\sOk|221\.*\s\w’|wc -l) == ‘5’ ]]; then echo "SMTP OK 1"; else echo "SMTP NOK 0"; fi)

Set the proper permissions so either file is owned by zabbix:zabbix or it is been able to be read from all system users.
 

# chmod a+r /etc/zabbix/zabbix_agent.d/userparameter_smtp_check.conf

2. Create a new Template for the Mail server monitoring
 


 

Just like any other template name it with what fits you as you see, I've call it PROD SMTP Monitoring, as the template is prepared to specifically monitor In Production Linux machines, and a separate template is used to monitor the Quality Assurance (QAs) as well as PreProd (Pre Productions).

3. Create the followng Items and Depedent Item to process zabbix-agent received data from the Userparam script
 

Above is the list of basic Items and Dependent Item you will need to configure inside the SMTP Check zabbix Template.

The Items should have the following content and configurations:
 

/postfix-main-proc-service-item-zabbix-shot


*Name: postfix_main_proc.service
Type: Zabbix agent(active)
*Key: proc.num[master,root]
Type of Information: Numeric (unassigned)
*Update interval: 30s
Custom Intervals: Flexible
*History storage period: 90d
*Trend storage period: 365d
Show Value: as is
Applications: Postfix Checks
Populated host inventory field: -None-
Description: The item counts master daemon process that runs Postfix daemons on demand

Where the arguments pased to proc.num[] function are:
  master is the process that is being looked up for and root is the username with which the the postfix master daemon is running. If you need to adapt it for qmail or exim that shouldn't be a big deal you only have to in advance check the exact processes that are normally running on the machine
and configure a similar process check for it.

*Name: postfix_sub_procs.service_cnt
Type: Zabbix agent(active)
*Key: proc.num[,postfix]
Type of information: Numeric (unassigned)
Update Interval: 30s
*History Storage period: Storage Period 90d
*Trend storage period: Storage Period 365d
Description: The item counts master daemon processes that runs postfix daemons on demand.

Here the idea with this Item is to check the number of processes that are running with user / groupid that is postfix. Again for other SMPT different from postfix, just set it to whatever user / group 
you would like zabbix to look up for in Linux the process list. As you can see here the check for existing postfix mta process is done every 30 seconds (for more critical environments you can put it to less).

For simple zabbix use this Dependent Item is not necessery required. But as we would like to process more closely the output of the userparameter smtp script, you have to set it up.
If you want to write graphical representation by sending data to Grafana.

*Name: postfix availability check
Key: postfix_boolean_check[boolean]
Master Item: PROD SMTP Monitoring: postfix availability check
Type of Information: Numeric unassigned
*History storage period: Storage period 90d
*Trend storage period: 365d
Applications: Postfix Checks
Description: It returns boolean value of SMTP check
1 – True (SMTP is OK)
0 – False (SMTP does not responds)
Enabled: Tick

*Name: postfix availability check
*Key: smtp.check
Custom intervals: Flexible
*Update interval: 30 m
History sotrage period: Storage Period 90d
Applications: Postfix Checks
Populates host inventory field: -None-
Description: This check is testing if the SMTP relay is reachable, without actual sending an email
Enabled: Tick

4. Configure following Zabbix Triggers

 

Note: The severity levels you should have previosly set in Zabbix up to your desired ones.

Name: postfix master root process is not running
*Problem Expression: {PROD SMTP Monitoring:proc.num[master,root].last()}<1
OK event generation: Recovery expression
*Recovery Expression: {PROD SMTP Monitoring:proc.num[master,root].last()}>=1
Allow manual close: Tick
Description: The item counts master daemon process that runs Postfix daemon on demand.
Enabed: Tick

I would like to have an AUTO RESOLVE for any detected mail issues, if an issue gets resolved. That is useful especially if you don't have the time to put the Zabbix monitoring in Maintainance Mode during Operating system planned updates / system reboots or unexpected system reboots due to electricity power loss to the server colocated – Data Center / Rack . 


*Name: postfix master sub processes are not running
*Problem Expression: {P09 PROD SMTP Monitoring:proc.num[,postfix].last()}<1
PROBLEM event generation mode: Single
OK event closes: All problems
*Recovery Expression: {P09 PROD SMTP Monitoring:proc.num[,postfix].last()}>=1
Problem event generation mode: Single
OK event closes: All problems
Allow manual close: Tick
Enabled: Tick

Name: SMTP connectivity check
Severity: WARNING
*Expression: {PROD SMTP Monitoring:postfix_boolen_check[boolean].last()}=0
OK event generation: Expression
PROBLEM even generation mode: SIngle
OK event closes: All problems
Allow manual close: Tick
Enabled: Tick

5. Configure respective Zabbix Action

 

zabbix-configure-Actions-screenshotpng
 

As the service is tagged with 'pci service' tag we define the respective conditions and according to your preferences, add as many conditions as you need for the Zabbix Action to take place.

NOTE! :
Assuming that communication chain beween Zabbix Server -> Zabbix Proxy (if zabbix proxy is used) -> Zabbix Agent works correctly you should start receiving that from the userparameter script in Zabbix with the configured smtp.check userparam key every 30 minutes.
Note that this simple nc check will keep a trail records inside your /var/log/maillog for each netcat connection, so keep in mind that in /var/log/maillog on each host which has configured the SMTP Check zabbix template, you will have some records  similar to:

# tail -n 50 /var/log/maillog
2023-06-22T09:32:18.164128+02:00 lpgblu01f postfix/smtpd[2690485]: improper command pipelining after HELO from localhost[127.0.0.1]:  MAIL FROM: root@your-machine-fqdn-address.com\n RCPT TO: your-supposable-receive-addr@whatever-mail-address.com\n  QUIT\n
2023-06-22T09:32:18.208888+02:00 lpgblu01f postfix/smtpd[2690485]: 32EB02005B: client=localhost[127.0.0.1]
2023-06-22T09:32:18.209142+02:00 lpgblu01f postfix/smtpd[2690485]: disconnect from localhost[127.0.0.1] helo=1 mail=1 rcpt=1 quit=1 commands=4
2023-06-22T10:02:18.889440+02:00 lpgblu01f postfix/smtpd[2747269]: connect from localhost[127.0.0.1]
2023-06-22T10:02:18.889553+02:00 lpgblu01f postfix/smtpd[2747269]: improper command pipelining after HELO from localhost[127.0.0.1]:  MAIL FROM: root@your-machine-fqdn-address.com\n RCPT TO: your-supposable-receive-addr@whatever-mail-address.com\n  QUIT\n
2023-06-22T10:02:18.933933+02:00 lpgblu01f postfix/smtpd[2747269]: E3ED42005B: client=localhost[127.0.0.1]
2023-06-22T10:02:18.934227+02:00 lpgblu01f postfix/smtpd[2747269]: disconnect from localhost[127.0.0.1] helo=1 mail=1 rcpt=1 quit=1 commands=4
2023-06-22T10:32:26.143282+02:00 lpgblu01f postfix/smtpd[2804195]: connect from localhost[127.0.0.1]
2023-06-22T10:32:26.143439+02:00 lpgblu01f postfix/smtpd[2804195]: improper command pipelining after HELO from localhost[127.0.0.1]:  MAIL FROM: root@your-machine-fqdn-address.com\n RCPT TO: your-supposable-receive-addr@whatever-mail-address.com\n  QUIT\n
2023-06-22T10:32:26.186681+02:00 lpgblu01f postfix/smtpd[2804195]: 2D7F72005B: client=localhost[127.0.0.1]
2023-06-22T10:32:26.186958+02:00 lpgblu01f postfix/smtpd[2804195]: disconnect from localhost[127.0.0.1] helo=1 mail=1 rcpt=1 quit=1 commands=4
2023-06-22T11:02:26.924039+02:00 lpgblu01f postfix/smtpd[2860398]: connect from localhost[127.0.0.1]
2023-06-22T11:02:26.924160+02:00 lpgblu01f postfix/smtpd[2860398]: improper command pipelining after HELO from localhost[127.0.0.1]:  MAIL FROM: root@your-machine-fqdn-address.com\n RCPT TO: your-supposable-receive-addr@whatever-mail-address.com\n  QUIT\n
2023-06-22T11:02:26.963014+02:00 lpgblu01f postfix/smtpd[2860398]: EB08C2005B: client=localhost[127.0.0.1]
2023-06-22T11:02:26.963257+02:00 lpgblu01f postfix/smtpd[2860398]: disconnect from localhost[127.0.0.1] helo=1 mail=1 rcpt=1 quit=1 commands=4
2023-06-22T11:32:29.145553+02:00 lpgblu01f postfix/smtpd[2916905]: connect from localhost[127.0.0.1]
2023-06-22T11:32:29.145664+02:00 lpgblu01f postfix/smtpd[2916905]: improper command pipelining after HELO from localhost[127.0.0.1]:  MAIL FROM: root@your-machine-fqdn-address.com\n RCPT TO: your-supposable-receive-addr@whatever-mail-address.com\n  QUIT\n
2023-06-22T11:32:29.184539+02:00 lpgblu01f postfix/smtpd[2916905]: 2CF7D2005B: client=localhost[127.0.0.1]
2023-06-22T11:32:29.184729+02:00 lpgblu01f postfix/smtpd[2916905]: disconnect from localhost[127.0.0.1] helo=1 mail=1 rcpt=1 quit=1 commands=4
 

 

That's all folks use the :
Configuration -> Host (menu)

and assign the new SMTP check template to as many of the Linux hosts where you have setup the Userparameter script and Enjoy the new mail server monitoring at hand.

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Posted in Linux, Monitoring, System Administration, Zabbix | 3 Comments »

Install specific zabbix-agent version / Downgrade Zabbix Agent client to exact preferred old RPM version on CentOS / Fedora / RHEL Linux from repo

Wednesday, June 7th, 2023

zabbix-update-downgrade-on-centos-rhel-fedora-and-other-rpm-based-linux-zabbix-logo

 

In below article, I'll give you the short Update zabbix procedure to specific version release, if you need to have it running in tandem with rest of zabbix infra, as well as expain shortly how to downgrade zabbix version to a specific release number
to match your central zabbix-serveror central zabbix proxies.

The article is based on personal experience how to install / downgrade the specific zabbuix-agent  release on RPM based distros.
I know this is pretty trivial stuff but still, hope this might be useful to some sysadmin out there thus I decided to quickly blog it.

 

1. Prepare backup of zabbix_agentd.conf
 

# cp -rpf /etc/zabbix/zabbix_agentd.conf /home/your-user/zabbix_agentd.conf.bak.$(date +"%b-%d-%Y")

 

2. Create zabbix repo source file in yum.repos.d directory

# cd /etc/yum.repos.d/
# vim zabbix.repo 

 

[zabbix-5.0]

name=Zabbix 5.0 repo

baseurl=http://zabixx-rpm-mirrors-site.com/centos/external/zabbix-5.0/8/x86_64/

enabled=1

gpgcheck=0

 

3. Update zabbix-agent to a specific defined version

# yum search zabbix-agent –enablerepo zabbix-5.0

To update zabbix-agent for RHEL 7.*

# yum install zabbix-agent-5.0.34-1.el7.x86_64


For RHEL 8.*

# yum install zabbix-agent-5.0.34-1.el8.x86_64


4. Restart zabbix-agentd and check its status to make sure it works correctly
 

# systemctl status zabbix-agentd
# systemctl restart zabbix-agentd
# systemctl status zabbix-agentd


Go to zabbix-server WEB GUI interface and check that data is delivered as normally in Latest Data for the host fom recent time, to make sure host monitoring is continuing flawlessly as before change.

NB !: If yum use something like versionlock is enabled remove the versionlock for package and update then, otherwise it will (weirldly look) look like the package is missing.
I'm saying that because I've hit this issue and was wondering why i cannot install the zabbix-agent even though the version is listed, available and downloadable from the repository.


5. Downgrade agent-client to specific version (Install old version of Zabbix from Repo)
 

Sometimes by mistake you might have raised the Zabbix-agent version to be higher release than the zabbix-server's version and thus breach out the Zabbix documentation official recommendation to keep
up the zabbix-proxy, zabbix-server and zabbix-agent at the exactly same version major and minor version releases. 

If so, then you would want to decrease / downgrade the version, to match your Zabbix overall infrastructure exact version for each of Zabbix server -> Zabbix Proxy server -> Agent clients.

To downgrade the version, I prefer to create some backups, just in case for all /etc/zabbix/ configurations and userparameter scripts (from experience this is useful as sometimes some RPM binary update packages might cause /etc/zabbix/zabbix_agentd.conf file to get overwritten. To prevent from restoring zabbix_agentd.conf from your most recent backup hence, I prefer to just crease the zabbix config backups manually.
 

# cd /root

# mkdir -p /root/backup/zabbix-agent 

# tar -czvf zabbix_agent.tar.gz /etc/zabbix/

# tar -xzvf zabbix_agent.tar.gz 


Then list the available installable zabbix-agent versions
 

[root@sysadminshelp:~]# yum –showduplicates list zabbix-agent
Заредени плъгини: fastestmirror
Determining fastest mirrors
 * base: centos.uni-sofia.bg
 * epel: fedora.ipacct.com
 * extras: centos.uni-sofia.bg
 * remi: mirrors.uni-ruse.bg
 * remi-php74: mirrors.uni-ruse.bg
 * remi-safe: mirrors.uni-ruse.bg
 * updates: centos.uni-sofia.bg
Инсталирани пакети
zabbix-agent.x86_64                                                     5.0.30-1.el7                                                     @zabbix
Налични пакети
zabbix-agent.x86_64                                                     5.0.0-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.1-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.2-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.3-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.4-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.5-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.6-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.7-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.8-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.9-1.el7                                                      zabbix
zabbix-agent.x86_64                                                     5.0.10-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.11-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.12-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.13-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.14-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.15-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.16-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.17-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.18-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.19-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.20-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.21-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.22-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.23-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.24-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.25-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.26-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.27-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.28-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.29-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.30-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.31-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.32-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.33-1.el7                                                     zabbix
zabbix-agent.x86_64                                                     5.0.34-1.el7                                                     zabbix

 

Next lets install the most recent zabbix-versoin from the CentOS repo, which for me as of time of writting this article is 5.0.34.

# yum downgrade -y zabbix-agent-5.0.34-1.el7

# cp -rpf /root/backup/zabbix-agent/etc/zabbix/zabbix_agentd.conf /etc/zabbix/

# systemctl start zabbix-agent.service

# systemctl enable  zabbix-agent.service
 

# zabbix_agentd -V
zabbix_agentd (daemon) (Zabbix) 5.0.30
Revision 2c96c38fb4b 28 November 2022, compilation time: Nov 28 2022 11:27:43

Copyright (C) 2022 Zabbix SIA
License GPLv2+: GNU GPL version 2 or later <https://www.gnu.org/licenses/>.
This is free software: you are free to change and redistribute it according to
the license. There is NO WARRANTY, to the extent permitted by law.

This product includes software developed by the OpenSSL Project
for use in the OpenSSL Toolkit (http://www.openssl.org/).

Compiled with OpenSSL 1.0.1e-fips 11 Feb 2013
Running with OpenSSL 1.0.1e-fips 11 Feb 2013
 

That's all folks you should be at your custom selected preferred version of zabbix-agent.
Enjoy ! 🙂

Tags: , , , , , , , , ,
Posted in Linux, Linux Package Management, Monitoring, Various, Zabbix | 2 Comments »

IPFilter firewall basics use for Adding / Removing and Cloning firewall rules

Thursday, June 1st, 2023

ipfilter-bsd-solaris-unix-firewall-short-review-ofLinux_firewalls-BSD_Firewall_logo

Linux users have most definitely used Netfilter (the older from us might remember and have used ipchains) and rest
should know well or at least partially tried iptables or if you have digged into Linux firewalls more professionally, might have tried nftables
and the newer firewalld (firewall-cmd) that is the standard nowadays in CentOS / Fedora and RHEL (again an abstraction over iptables.).
On Debian firewall is organized around custom shell scripts that deal with iptables chains, or if on Ubuntu perhaps you have tried UFW (The Uncomplicated Firewall)
frontend program for managing firewalls again with iptables. For the lazy ones UFW even has another GUI frontend called Gufw (intended to be easy, intuitive,
graphical user interface for managing Uncomlicated firewall.

Different Linux distributions do use a different set of firewall mechanisms preconfigure but there are other firewall solutions on other Unixes such as ipfilter.
That historically were heavily used that is worthy mentioning and if you happen to pop-up working as a network guy inside some large corporations you might face it.

IPFilter (commonly referred to as ipf) is an open-source software package that provides firewall services and network address translation (NAT) for many Unix-like operating systems.
The author and software maintainer is Darren Reed. IPFilter supports both IPv4 and IPv6 protocols, and is a stateful firewall.
IPFilter is delivered with FreeBSD, NetBSD, Solaris 10 & 11, illumos, OpenIndiana and HP-UX.
It used to be a part of OpenBSD, but it was removed by Theo de Raadt in May 2001 due to problems with its license.
It was subsequently replaced in OpenBSD by PF, which was developed by OpenBSD's own developers.
DragonFly BSD removed its support for IPFilter in May 2011.

IPFilter can be installed as a runtime-loadable kernel module or directly incorporated into the operating system kernel, depending on the specifics of each kernel and user preferences.
The software's documentation recommends the module approach, if possible.

Here are some commands for displaying, changing and distributing IP filters with ipfilter.
It will be mostly useful, if you happen to have some obsolete OS infrastructure or OpenBSD.

The commands given below are to add / remove and activate rules on machine with ipfilter:

# ipfilter –clone
# ipfilter –save
# ipfilter –activate
# ipfilter -addrule
# ipfilter -delrule
# help ipfilter

1. Check ipfilter current config

# ipfilter –show
Name: default_ipv4, Type: ipv4, State: active
Rule    Source IP                               Protocol   Dest Port   Action
1     any                                            tcp       22     permit
2     any                                            tcp       23     permit
3     any                                            tcp       80     permit
4     any                                            tcp      443     permit
5     any                                            udp      161     permit
6     any                                            udp      123     permit
7     any                                            tcp      600 – 1023     permit
8     any                                            udp      600 – 1023     permit
Name: default_ipv6, Type: ipv6, State: active
Rule    Source IP                               Protocol   Dest Port   Action
1     any                                            tcp       22     permit
2     any                                            tcp       23     permit
3     any                                            tcp       80     permit
4     any                                            tcp      443     permit
5     any                                            udp      161     permit
6     any                                            udp      123     permit
7     any                                            tcp      600 – 1023     permit
8     any                                            udp      600 – 1023     permit
Name: default_ipv4_new, Type: ipv4, State: defined
Rule    Source IP                               Protocol   Dest Port   Action
1     any                                            tcp       22     permit
2     any                                            tcp       23     permit
3     any                                            tcp       80     permit
4     any                                            tcp      443     permit
5     any                                            udp      161     permit
6     any                                            udp      123     permit
7     any                                            tcp      600 – 1023     permit
8     any                                            udp      600 – 1023     permit

2. Clone and activate ipfilter configuration

# ipfilter –clone default_ipv4_new -from default_ipv4
# ipfilter –activate default_ipv4_new
# ipfilter –show
Name: default_ipv4, Type: ipv4, State: defined
Rule    Source IP                               Protocol   Dest Port   Action
1     any                                            tcp       22     permit
2     any                                            tcp       23     permit
3     any                                            tcp       80     permit
4     any                                            tcp      443     permit
5     any                                            udp      161     permit
6     any                                            udp      123     permit
7     any                                            tcp      600 – 1023     permit
8     any                                            udp      600 – 1023     permit
Name: default_ipv6, Type: ipv6, State: active
Rule    Source IP                               Protocol   Dest Port   Action
1     any                                            tcp       22     permit
2     any                                            tcp       23     permit
3     any                                            tcp       80     permit
4     any                                            tcp      443     permit
5     any                                            udp      161     permit
6     any                                            udp      123     permit
7     any                                            tcp      600 – 1023     permit
8     any                                            udp      600 – 1023     permit
Name: default_ipv4_neu, Type: ipv4, State: active
Rule    Source IP                               Protocol   Dest Port   Action
1     any                                            tcp       22     permit
2     any                                            tcp       23     permit
3     any                                            tcp       80     permit
4     any                                            tcp      443     permit
5     any                                            udp      161     permit
6     any                                            udp      123     permit
7     any                                            tcp      600 – 1023     permit
8     any                                            udp      600 – 1023     permit

3. Modify cloned configuration

Lets say we would like to delete the telnet port accept traffic rule  (port 23)

# ipfilter –delrule default_ipv4_new -rule 2

To permit the rule agian

# ipfilter –addrule default_ipv4_new -rule 2 -sip any -dp 23 -proto tcp -act permit

To save the rule

# ipfilter –save default_ipv4_new                          

Tags: , , , , , , , , ,
Posted in Everyday Life, Firewall, Linux, System Optimization | 1 Comment »

Install btop on Debian Linux, btop an advanced htop like monitoring for Linux to beautify your console life

Tuesday, May 30th, 2023

btop-linux-monitoring-tool-screenshot-help-menu

I've accidently stubmled on btop a colorful and interactive ncurses like command line utility to provide you a bunch of information about CPU / memory / disks and processes with nice console graphic in the style of Cubic Player 🙂
Those who love htop and like their consoles to be full of shiny colors, will really appreciate those nice Linux monitoring tool.
To install btop on latest current stable Debian bullseyes, you will have to install it via backports, as the regular Debian repositories does not have the tool available out of the box.

To Add backports packages support for your Debian 11:

1. Edit /etc/apt/sources.list and include following repositories

 

# vim /etc/apt/sources.list

deb http://deb.debian.org/debian bullseye-backports main contrib non-free
deb-src http://deb.debian.org/debian bullseye-backports main contrib non-free


2. Update the known repos list to include it

 

# apt update
…


3. Install the btop deb package from backports

 

# apt-cache show btop|grep -A 20 -i descrip
Description-en: Modern and colorful command line resource monitor that shows usage and stats
 btop is a modern and colorful command line resource monitor that shows
 usage and stats for processor, memory, disks, network and processes.
 btop features:
  – Easy to use, with a game inspired menu system.
  – Full mouse support, all buttons with a highlighted key is clickable
  and mouse scroll works in process list and menu boxes.
  – Fast and responsive UI with UP, DOWN keys process selection.
  – Function for showing detailed stats for selected process.
  – Ability to filter processes.
  – Easy switching between sorting options.
  – Tree view of processes.
  – Send any signal to selected process.
  – UI menu for changing all config file options.
  – Auto scaling graph for network usage.
  – Shows IO activity and speeds for disks
  – Battery meter
  – Selectable symbols for the graphs
  – Custom presets
  – And more…
  btop is written in C++ and is continuation of bashtop and bpytop.
Description-md5: 73df6c70fe01f5bf05cca0e3031c1fe2
Multi-Arch: foreign
Homepage: https://github.com/aristocratos/btop
Section: utils
Priority: optional
Filename: pool/main/b/btop/btop_1.2.7-1~bpo11+1_amd64.deb
Size: 431500
SHA256: d79e35c420a2ac5dd88ee96305e1ea7997166d365bd2f30e14ef57b556aecb36


 

# apt install -t bullsye-backports btop –yes
…

Once I installed it, I can straight use it except on some of my Linux machines, which were having a strange encoding $LANG defined, those ones spitted some errors like:

root@freak:~# btop
ERROR: No UTF-8 locale detected!
Use –utf-force argument to force start if you're sure your terminal can handle it.
 


To work around it simply redefine LANG variable and rerun it
 

# export LANG=en_US.UTF8

# btop

 

btop-linux-monitoring-console-beautiful-colorful-tool-graphics-screenshot

btop-linux-monitoring-tool-screenshot-help-menu

Tags: , , , , , , , , ,
Posted in Linux, Monitoring, Various | 3 Comments »

How to log multiple haproxy / apache / mysql instance via haproxy log-tagging / Segregating log management for multiple HAProxy instances using rsyslog

Tuesday, May 23rd, 2023

rsyslog-logo-picture-use-programname-and-haproxy-log-tag-directives-together-to-log-as-many-process-streams-as-you-like

 

Introduction

This article provides a guide on refining haproxy  logging mechanism by leveraging the `programname` property in rsyslog, coupled with the `log-tag` directive in haproxy.
This approach will create a granular logging setup, separating logs according to their originating services and specific custom tags, enhancing overall log readability.

Though the article is written concretely for logging multiple log streams from haproxy this can be successfully applied
for any other Linux service to log as many concrete log-tagged data streams as you prefer.

Scope

The guide focuses on tailoring the logging mechanisms for two haproxy  instances named `haproxy` and `haproxyssl`, utilizing the `programname` property in rsyslog and the `log-tag` directive in haproxy for precise log management.

The haproxy and haproxyssl instances are two separate systemd config file prepared instances.
haproxy instance is simple haproxy proxying tcp traffic in non-encrypted form, whether haproxyssl is a special instance
prepared to tunnel the incoming http traffic in ssl form. Both instances of haproxy runs as a separate processes on the server.

Here is the systemd configuration of haproxy systemd service file:

# cat /usr/lib/systemd/system/haproxy.service
[Unit]
Description=HAProxy Load Balancer
After=network-online.target
Wants=network-online.target

[Service]
Environment="CONFIG=/etc/haproxy/haproxy.cfg" "PIDFILE=/run/haproxy.pid"
EnvironmentFile=/etc/sysconfig/haproxy
ExecStartPre=/usr/sbin/haproxy -f $CONFIG -c -q $OPTIONS
ExecStart=/usr/sbin/haproxy -Ws -f $CONFIG -p $PIDFILE $OPTIONS
ExecReload=/usr/sbin/haproxy -f $CONFIG -c -q $OPTIONS
ExecReload=/bin/kill -USR2 $MAINPID
SuccessExitStatus=143
KillMode=mixed
Type=notify

[Install]
WantedBy=multi-user.target


As well as the systemd service configuration for haproxyssl:
 

# cat /usr/lib/systemd/system/haproxyssl.service
[Unit]
Description=HAProxy Load Balancer
After=network-online.target
Wants=network-online.target

[Service]
Environment="CONFIG=/etc/haproxy/haproxy_ssl_prod.cfg" "PIDFILE=/run/haproxy_ssl_prod.pid"
EnvironmentFile=/etc/sysconfig/haproxy
ExecStartPre=/usr/sbin/haproxyssl -f $CONFIG -c -q $OPTIONS
ExecStart=/usr/sbin/haproxyssl -Ws -f $CONFIG -p $PIDFILE $OPTIONS
ExecReload=/usr/sbin/haproxyssl -f $CONFIG -c -q $OPTIONS
ExecReload=/bin/kill -USR2 $MAINPID
SuccessExitStatus=143
KillMode=mixed
Type=notify

[Install]
WantedBy=multi-user.target

 

Step 1: Configuring HAProxy instances with `log-tag`
 

To distinguish between logs from two HAProxy instances, `log-tag` directive is used to add tags to logs. This tag is used to filter these logs in rsyslog.
Modify the HAProxy configuration file in `/etc/haproxy/haproxy.*.cfg`

HAProxy Instance 1 (haproxy)
 

#———————————————————————
# Global settings
#———————————————————————
global
      log          127.0.0.1 local6 debug
      log-tag      haproxy

HAProxy Instance 2 (haproxyssl)


#———————————————————————
# Global settings
#———————————————————————
global
    log          127.0.0.1 local5 debug
    log-tag      haproxyssl

 

Step 2: Implementing rsyslog configuration for haproxy logs
 

Next, create a new rsyslog configuration file, stored in /etc/rsyslog.d/. Ensure the new configuration file ends in `.conf`

HAProxy Instance 1 (haproxy)

Now add rsyslog rules to filters logs based on the `programname` and the custom log tag:
 

# vi /etc/rsyslog.d/55_haproxy.conf
if $programname == 'haproxy' then /var/log/haproxy.log
&stop

HAProxy Instance 2 (haproxyssl)
# vi /etc/rsyslog.d/51_haproxy_ssl.conf
if $programname == 'haproxy_ssl' then /var/log/haproxy_ssl.log
&stop


These rules filter logs that originate from haproxy  and contain the respective string haproxy   or haproxy_ssl , directing them to their respective log files. The `& stop` directive ensures that rsyslog stops processing the log once a match is found, preventing dublication.

Finally, restart both the haproxy and rsyslog services for the changes to take effect:

# systemctl restart haproxy
# systemctl restart haproxyssl
# systemctl restart rsyslog


Reading References

haproxy:   log-tag directive

rsyslog:    rsyslogd documentation

This is a guest article originally written by: Dimitar Paskalev, guest blogging with good interesting articles is always mostly welcome 

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Posted in Educational, Hacks, Linux | 1 Comment »

Perl Modules via HTTP Proxy installation, update and install perl CPAN modules behind a Firewall DMZ-ed networks

Friday, May 19th, 2023

If you have to maintain perl script written applications on Linux servers that are sitting behind a very paranoid set-up firewalls
and Local DMZ network, but you still need to maintain the servers and applications versions including perl CPAN (Comprehensive Perl Archive networking) module libraries, you could still do so via another Proxy machine Hub on the Local network, where you either have to manually download all the newest perl versions and CPAN module (libraries) or you can set it up that Proxy machine
to access only a specific Secured internet URLs for perl stuff.

Proxying perl downloads can be done via FTP connects, but as FTP is communicating in plain text and the protocol is known
for not behaving very well behind firewalls, it is a better idea to use for CPAN downloads HTTP or HTTPS protocol.

Normlly Perl is using FTP to download files from the internet. To enable Perl using also HTTP, please install the following RPM:

# yum install perl-libwww-perl

After figure out a CPAN-mirror from http://mirrors.cpan.org/search.cgi?country=Germany, we can start with the configuration from CPAN.

or debian package

# apt install libwww-perl

At the first run from /usr/bin/cpan the initial configuration will be started up which will be done automatically:

[username@linux-host ~]$ cpan

/home/linux-username/.cpan/CPAN/MyConfig.pm initialized.


CPAN is the world-wide archive of perl resources. It consists of about
100 sites that all replicate the same contents all around the globe.
Many countries have at least one CPAN site already. The resources
found on CPAN are easily accessible with the CPAN.pm module. If you
want to use CPAN.pm, you have to configure it properly.

If you do not want to enter a dialog now, you can answer 'no' to this
question and I'll try to autoconfigure. (Note: you can revisit this
dialog anytime later by typing 'o conf init' at the cpan prompt.)

Are you ready for manual configuration? [yes] no

— SNIP — SNAP — SNIP — SNAP — SNIP — SNAP —

commit: wrote /home/linux-username/.cpan/CPAN/MyConfig.pm
Terminal does not support AddHistory.

cpan shell — CPAN exploration and modules installation (v1.7602)
ReadLine support available (try 'install Bundle::CPAN')

cpan> q
Terminal does not support GetHistory.
Lockfile removed.
[username@linux-host ~]$

After the initial configuration you have to run /usr/bin/cpan again, to configure the HTTP-proxy and an alternative HTTP-URL for the default FTP URL:
 

[username@linux-host ~]$ cpan
Terminal does not support AddHistory.

cpan shell — CPAN exploration and modules installation (v1.7602)
ReadLine support available (try 'install Bundle::CPAN')

cpan> o conf http_proxy http://proxy-host-to-internet.com:8080
    http_proxy         http://proxy-host-to-internet.com:8080

cpan> o conf urllist push http://mirrors.zerg.biz/cpan/

cpan> o conf commit
commit: wrote /home/linux-username/.cpan/CPAN/MyConfig.pm

cpan> q
Terminal does not support GetHistory.
Lockfile removed.
[username@linux-host ~]$

From now CPAN will load it's files from the internet with the HTTP-proxy:
 

[username@linux-host ~]$ cpan
Terminal does not support AddHistory.

cpan shell — CPAN exploration and modules installation (v1.7602)
ReadLine support available (try 'install Bundle::CPAN')

cpan> i  Example::DB::Oracle
CPAN: Storable loaded ok
CPAN: LWP::UserAgent loaded ok
Fetching with LWP:
  http://mirrors.zerg.biz/cpan/authors/01mailrc.txt.gz
Going to read /home/linux-host/.cpan/sources/authors/01mailrc.txt.gz
Fetching with LWP:
  http://mirrors.zerg.biz/cpan/modules/02packages.details.txt.gz
Going to read /home/linux-host/.cpan/sources/modules/02packages.details.txt.gz
  Database was generated on Thu, 07 Jan 2010 10:44:22 GMT

  There's a new CPAN.pm version (v1.9402) available!
  [Current version is v1.7602]
  You might want to try
    install Bundle::CPAN
    reload cpan
  without quitting the current session. It should be a seamless upgrade
  while we are running…

Fetching with LWP:
  http://mirrors.zerg.biz/cpan/modules/03modlist.data.gz
Going to read /home/linux-username/.cpan/sources/modules/03modlist.data.gz
Going to write /home/linux-username/.cpan/Metadata
Strange distribution name [Example::DB::Oracle]
Module id = Example::DB::Oracle
    CPAN_USERID  MSERGEANT (MSERGEANT <msergeant@cpan.org>)
    CPAN_VERSION undef
    CPAN_FILE    M/MS/MSERGEANT/DBIx-AnyDBD-2.01.tar.gz
    INST_FILE    (not installed)

cpan> q
Terminal does not support GetHistory.
Lockfile removed.

Now as the new proxy http URL http://proxy-host-to-internet.com:8080 is set on the machine, to upgrade the existing modules non interactively

# perl MCPAN -e upgrade

or do it the old fashioned way via the MCPAN perl shell:

# perl -MCPAN -e shell

Starting with version 2.29 of the cpan shell, a new download mechanism
is the default which exclusively uses cpan.org as the host to download
from. The configuration variable pushy_https can be used to (de)select
the new mechanism. Please read more about it and make your choice
between the old and the new mechanism by running

    o conf init pushy_https

Once you have done that and stored the config variable this dialog
will disappear.

cpan shell — CPAN exploration and modules installation (v2.29)
Enter 'h' for help.

cpan[1]> upgrade
…

That's all folks after a while if no errors are spit during the Perl modules update you'll be at the latest versions of CPAN and modules.
 

 

Tags: , , , , , , , , ,
Posted in Linux, System Administration | 2 Comments »

Install Zabbix Proxy configure and connect to Zabbix server on CentOS Linux

Thursday, May 4th, 2023

Install Zabbix Proxy configure and connect to Zabbix server on CentOS Linux

1. Why use Zabbix-Proxy hidden advantages of using Zabbix-Proxy ?
 

Proxy can be used for many purposes and can provide many hidden benefits, just to name few of them:

  • Offload Zabbix Server when monitoring thousands of devices
  • Monitor remote locations
  • Monitor locations having unreliable communications
  • Simplify maintenance of distributed monitoring
  • Improved Security (Zabbix server can be restricted to be connectable only by the set of connected Zabbix Proxy / Proxies


advantages-of-using-zabbix-proxy-instead-of-direct-connect-monitored-hosts-to-zabbix-server-diagram

 

A Zabbix proxy is the ideal solution if you have numerous hosts with multiple slow items that are affecting the performance of the server simply because processes are spending most of the time simply waiting for a response. A proxy can collect information from all hosts using its internal processes and then send raw historical data to the server. The time needed to connect and receive the host response will be on the proxy site, and the server performance will not be affected at all. A proxy just sends raw values to the server, and the server itself does not have to connect to the host to get the data.
 

2. Install zabbix-proxy-sqlite3 rpm package from Zabbix Official Repositories download page

Zabbix repository provides choice of 3 packages named as follows:

zabbix-proxy-mysql
zabbix-proxy-pgsql
zabbix-proxy-sqlite3

where the last value of the name (after zabbix-proxy) represents database type of the package — MySQL, PostgreSQL and SQLite respectively.

To not bother installing MySQL / PostgreSQL separate database servers, a lightweight choice is to use the sqlite3 db version. 
As I prefer zabbix-proxy data to be stored inside a flat database, thus I choose to use zabbix-proxy-sqlite3.

[root@sysadminshelp:/root ]# yum info zabbix-proxy-sqlite3-5.0.31-1.el7.x86_64
Заредени плъгини: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.netix.net
 * epel: fedora.ipacct.com
 * extras: mirrors.netix.net
 * remi: remi.mirror.karneval.cz
 * remi-php74: remi.mirror.karneval.cz
 * remi-safe: remi.mirror.karneval.cz
 * updates: mirrors.netix.net
Инсталирани пакети
Име         : zabbix-proxy-sqlite3
Архитект.   : x86_64
Версия      : 5.0.31
Издание     : 1.el7
Обем        : 4.4 M
Хранилище   : installed
Обобщение   : Zabbix proxy for SQLite3 database
URL         : http://www.zabbix.com/
Лиценз      : GPLv2+
Описание    : Zabbix proxy with SQLite3 database support.

My experience to try to install thethe default CentOS RPM package for zabbix-proxy-sqlite3 provided by default
RPM package that came with CentOS did not work as expected and trying to install / configure and use it via

[root@sysadminshelp:/root ]# yum install zabbix-proxy-sqlite3.x86_64 -y

[root@sysadminshelp:/root ]# vi /etc/zabbix/zabbix_proxy.conf


Led me to a nasty errors seen in /var/log/zabbixsrv/zabbix_proxy.log like:

May 1st 2023, 08:42:45.020 zabbix_server cannot set list of PSK ciphersuites: file ssl_lib.c line 1314: error:1410D0B9:SSL routines:SSL_CTX_set_cipher_list:no cipher match
May 1st 2023, 08:42:45.018 zabbix_server cannot set list of PSK ciphersuites: file ssl_lib.c line 1314: error:1410D0B9:SSL routines:SSL_CTX_set_cipher_list:no cipher match
May 1st 2023, 08:42:45.013 zabbix_server cannot set list of PSK ciphersuites: file ssl_lib.c line 1314: error:1410D0B9:SSL routines:SSL_CTX_set_cipher_list:no cipher match
May 1st 2023, 08:42:45.013 zabbix_server cannot set list of PSK ciphersuites: file ssl_lib.c line 1314: error:1410D0B9:SSL routines:SSL_CTX_set_cipher_list:no cipher match
May 1st 2023, 08:42:45.011 zabbix_server cannot set list of PSK ciphersuites: file ssl_lib.c line 1314: error:1410D0B9:SSL routines:SSL_CTX_set_cipher_list:no cipher match


After some googling and reading some threads came upon this one https://support.zabbix.com/browse/ZBXNEXT-3604, there is exmplaed errors preventing the configured zabbix-proxy
to start are caused by the zabbix-proxy-sqlite3 package provided by Redhat (due to openssl incompitability bug or something ).

As one of people in the discussion pointed out the quickest workaround suggested is simply to use the official Zabbix Repository packages for zabbix-proxy-sqlite3, in order to not waste anymore time on this
trivial stuff to install it, simply run:

[root@sysadminshelp:/root ]# rpm -Uvh \
https://repo.zabbix.com/zabbix/5.0/rhel/7/x86_64/zabbix-proxy-sqlite3-5.0.31-1.el7.x86_64.rpm

Alternative way if you seem to not have the machine connected to the internet is simply download the package with wget / lynx / curl / w3m from another machine 
that can reach the Internet upload the package via the local LAN or VPN and install it:

# wget https://repo.zabbix.com/zabbix/5.0/rhel/7/x86_64/zabbix-proxy-sqlite3-5.0.31-1.el7.x86_64.rpm …

[root@sysadminshelp:/root ]# rpm -ivh zabbix-proxy-sqlite3-5.0.31-1.el7.x86_64.rpm

NOTE ! Before you install proxy, keep in mind that your proxy version must match the Zabbix server version !

3. Generate a PSK random secret key and set proper permissions for zabbix-proxy directories


[root@sysadminshelp:/root ]# cd /etc/zabbix/
    
[root@sysadminshelp:/root ]# openssl rand -hex 32 >> /etc/zabbix/zabbix_proxy.psk     
[root@sysadminshelp:/root ]# chown root:zabbix zabbix_proxy.psk [root@sysadminshelp:/root ]# vi /etc/zabbix/zabbix_proxy.conf [root@sysadminshelp:/root ]# mkdir -p /var/lib/zabbix-proxy/sqlite3db
[root@sysadminshelp:/root ]# chown -R zabbix:zabbix /var/lib/zabbix-proxy
[root@sysadminshelp:/var/lib/zabbixsrv/sqlite3db]# sqlite3 zabbix_proxy
SQLite version 3.7.17 2013-05-20 00:56:22
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .databases
seq  name             file
—  —————  ———————————————————-
0    main             /var/lib/zabbixsrv/sqlite3db/zabbix_proxy
sqlite> [root@sysadminshelp:/root ]# vi /etc/zabbix_proxy.conf
#DBName=zabbix_proxy
DBName=/var/lib/zabbixsrv/sqlite3db/zabbix_proxy

4. Configure zabbix proxy to be able to connect to Zabbix Server

[root@sysadminshelp:/root ]#  vi /etc/zabbix/zabbix_proxy.conf     ############ GENERAL PARAMETERS #################
    ProxyMode=0
    Server=192.168.1.28
    ServerPort=10051
    Hostname=zabbix-proxy
    ListenPort=10051
    SourceIP=10.168.1.55
    LogFile=/var/log/zabbix/zabbix_proxy.log
    LogFileSize=1
    DebugLevel=2
    PidFile=/var/run/zabbix/zabbix_proxy.pid
    DBName=/var/lib/zabbix-proxy/sqlite3db/zabbix_proxy.db
    DBUser=zabbix
    
    ######### PROXY SPECIFIC PARAMETERS #############
    ProxyOfflineBuffer=24
    HeartbeatFrequency=60
    ConfigFrequency=120
    
    ############ ADVANCED PARAMETERS ################
    StartPollersUnreachable=3
    StartHTTPPollers=3
    JavaGateway=127.0.0.1
    JavaGatewayPort=10052
    StartJavaPollers=5
    SNMPTrapperFile=/var/log/snmptrap/snmptrap.log
    StartSNMPTrapper=1
    CacheSize=32M
    Timeout=4
    ExternalScripts=/usr/lib/zabbix/externalscripts
    LogSlowQueries=3000
    
    ####### TLS-RELATED PARAMETERS #######
    TLSConnect=psk
    TLSAccept=psk
    TLSPSKIdentity=PSK zabbix-proxy-fqdn-hostname
    TLSPSKFile=/etc/zabbix/zabbix_proxy.psk

5. Check and make sure the installed zabbix proxy as well as the zabbix_proxy server zabbix_agentd client and zabbix_server are at the same major version release

a) Check zabbix proxy version

[root@sysadminshelp:/etc/zabbix]# zabbix_proxy -V
zabbix_proxy (Zabbix) 5.0.31
Revision f64a07aefca 30 January 2023, compilation time: Jan 30 2023 09:55:10

Copyright (C) 2023 Zabbix SIA
License GPLv2+: GNU GPL version 2 or later <https://www.gnu.org/licenses/>.
This is free software: you are free to change and redistribute it according to
the license. There is NO WARRANTY, to the extent permitted by law.

This product includes software developed by the OpenSSL Project
for use in the OpenSSL Toolkit (http://www.openssl.org/).

Compiled with OpenSSL 1.0.1e-fips 11 Feb 2013
Running with OpenSSL 1.0.1e-fips 11 Feb 2013
[root@sysadminshelp:/etc/zabbix]#

b) check zabbix_agentd version

[root@sysadminshelp:/etc/zabbix]# zabbix_agentd -V
zabbix_agentd (daemon) (Zabbix) 5.0.30
Revision 2c96c38fb4b 28 November 2022, compilation time: Nov 28 2022 11:27:43

Copyright (C) 2022 Zabbix SIA
License GPLv2+: GNU GPL version 2 or later <https://www.gnu.org/licenses/>.
This is free software: you are free to change and redistribute it according to
the license. There is NO WARRANTY, to the extent permitted by law.

This product includes software developed by the OpenSSL Project
for use in the OpenSSL Toolkit (http://www.openssl.org/).

Compiled with OpenSSL 1.0.1e-fips 11 Feb 2013
Running with OpenSSL 1.0.1e-fips 11 Feb 2013

c) Check zabbix server version

[root@zabbix:~]# zabbix_server -V
zabbix_server (Zabbix) 5.0.30
Revision 2c96c38fb4b 28 November 2022, compilation time: Nov 28 2022 09:19:03

Copyright (C) 2022 Zabbix SIA
License GPLv2+: GNU GPL version 2 or later <https://www.gnu.org/licenses/>.
This is free software: you are free to change and redistribute it according to
the license. There is NO WARRANTY, to the extent permitted by law.

This product includes software developed by the OpenSSL Project
for use in the OpenSSL Toolkit (http://www.openssl.org/).

Compiled with OpenSSL 1.1.1d  10 Sep 2019
Running with OpenSSL 1.1.1n  15 Mar 2022

6. Starting the zabbix-proxy for a first time

Before beginning with installation make sure selinux is disabled, as it might cause some issues with Zabbix

[root@sysadminshelp:/etc/zabbix]# sestatus
SELinux status:                 disabled

If you need to have the selinux enabled you will have to allow the zabbix-proxy into selinux as well:

# cd /tmp
# grep zabbix_proxy /var/log/audit/audit.log | grep denied | audit2allow -m zabbix_proxy > zabbix_proxy.te
# grep zabbix_proxy /var/log/audit/audit.log | grep denied | audit2allow -M zabbix_proxy
# semodule -i zabbix_proxy.pp


[root@sysadminshelp:/etc/zabbix]# systemctl start zabbix-proxy

Also lets enable zabbix-proxy to automatically start it on next server reboot / boot.

root@sysadminshelp:/etc/zabbix]# systemctl enable zabbix-proxy

Normally running zabbix-proxy should provide a status messages like:

[root@sysadminshelp:/etc/zabbix]# systemctl status zabbix-proxy
● zabbix-proxy.service – Zabbix Proxy
   Loaded: loaded (/usr/lib/systemd/system/zabbix-proxy.service; disabled; vendor preset: disabled)
   Active: active (running) since чт 2023-05-04 14:58:36 CEST; 2h 59min ago
  Process: 8500 ExecStop=/bin/kill -SIGTERM $MAINPID (code=exited, status=0/SUCCESS)
  Process: 8504 ExecStart=/usr/sbin/zabbix_proxy -c $CONFFILE (code=exited, status=0/SUCCESS)
 Main PID: 8506 (zabbix_proxy)
   CGroup: /system.slice/zabbix-proxy.service
           ├─8506 /usr/sbin/zabbix_proxy -c /etc/zabbix/zabbix_proxy.conf
           ├─8507 /usr/sbin/zabbix_proxy: configuration syncer [synced config 40521 bytes in 0.0…
           ├─8508 /usr/sbin/zabbix_proxy: trapper #1 [processed data in 0.000808 sec, waiting fo…
           ├─8509 /usr/sbin/zabbix_proxy: trapper #2 [processed data in 0.005028 sec, waiting fo…
           ├─8510 /usr/sbin/zabbix_proxy: trapper #3 [processed data in 0.001240 sec, waiting fo…
           ├─8511 /usr/sbin/zabbix_proxy: trapper #4 [processed data in 0.004378 sec, waiting fo…
           ├─8512 /usr/sbin/zabbix_proxy: trapper #5 [processed data in 0.004991 sec, waiting fo…
           ├─8513 /usr/sbin/zabbix_proxy: preprocessing manager #1 [queued 0, processed 3 values…
           ├─8514 /usr/sbin/zabbix_proxy: preprocessing worker #1 started
           ├─8515 /usr/sbin/zabbix_proxy: preprocessing worker #2 started
           ├─8516 /usr/sbin/zabbix_proxy: preprocessing worker #3 started
           ├─8517 /usr/sbin/zabbix_proxy: heartbeat sender [sending heartbeat message success in…
           ├─8518 /usr/sbin/zabbix_proxy: data sender [sent 0 values in 0.005241 sec, idle 1 sec…
           ├─8519 /usr/sbin/zabbix_proxy: housekeeper [deleted 4501 records in 0.011462 sec, idl…
           ├─8520 /usr/sbin/zabbix_proxy: http poller #1 [got 0 values in 0.000248 sec, idle 5 s…
           ├─8521 /usr/sbin/zabbix_proxy: http poller #2 [got 0 values in 0.000239 sec, idle 5 s…
           ├─8522 /usr/sbin/zabbix_proxy: http poller #3 [got 0 values in 0.000328 sec, idle 5 s…
           ├─8523 /usr/sbin/zabbix_proxy: discoverer #1 [processed 0 rules in 0.000261 sec, idle…
           ├─8524 /usr/sbin/zabbix_proxy: history syncer #1 [processed 0 values in 0.000009 sec,…
           ├─8525 /usr/sbin/zabbix_proxy: history syncer #2 [processed 0 values in 0.000007 sec,…
           ├─8526 /usr/sbin/zabbix_proxy: history syncer #3 [processed 0 values in 0.000014 sec,…
           ├─8527 /usr/sbin/zabbix_proxy: history syncer #4 [processed 0 values in 0.000021 sec,…
           ├─8528 /usr/sbin/zabbix_proxy: java poller #1 [got 0 values in 0.000017 sec, idle 5 s…
           ├─8529 /usr/sbin/zabbix_proxy: java poller #2 [got 0 values in 0.000019 sec, idle 5 s…
           ├─8530 /usr/sbin/zabbix_proxy: java poller #3 [got 0 values in 0.000019 sec, idle 5 s…
           ├─8531 /usr/sbin/zabbix_proxy: java poller #4 [got 0 values in 0.000018 sec, idle 5 s…
           ├─8532 /usr/sbin/zabbix_proxy: java poller #5 [got 0 values in 0.000013 sec, idle 5 s…
           ├─8533 /usr/sbin/zabbix_proxy: snmp trapper [processed data in 0.000026 sec, idle 1 s…
           ├─8534 /usr/sbin/zabbix_proxy: self-monitoring [processed data in 0.000034 sec, idle …
           ├─8535 /usr/sbin/zabbix_proxy: task manager [processed 0 task(s) in 0.000169 sec, idl…
           ├─8536 /usr/sbin/zabbix_proxy: poller #1 [got 0 values in 0.000012 sec, idle 5 sec]
           ├─8537 /usr/sbin/zabbix_proxy: poller #2 [got 0 values in 0.000021 sec, idle 5 sec]
           ├─8538 /usr/sbin/zabbix_proxy: poller #3 [got 0 values in 0.000039 sec, idle 5 sec]
           ├─8539 /usr/sbin/zabbix_proxy: poller #4 [got 0 values in 0.000024 sec, idle 5 sec]
           ├─8540 /usr/sbin/zabbix_proxy: poller #5 [got 0 values in 0.000019 sec, idle 5 sec]
           ├─8541 /usr/sbin/zabbix_proxy: unreachable poller #1 [got 0 values in 0.000011 sec, i…
           ├─8542 /usr/sbin/zabbix_proxy: unreachable poller #2 [got 0 values in 0.000018 sec, i…
           ├─8543 /usr/sbin/zabbix_proxy: unreachable poller #3 [got 0 values in 0.000041 sec, i…
           └─8544 /usr/sbin/zabbix_proxy: icmp pinger #1 [got 0 values in 0.000022 sec, idle 5 s…

май 04 14:58:36 sysadminshelp systemd[1]: Stopped Zabbix Proxy.
май 04 14:58:36 sysadminshelp systemd[1]: Starting Zabbix Proxy…
май 04 14:58:36 sysadminshelp systemd[1]: Started Zabbix Proxy.

zabbix-server-zabbix-proxy-and-zabbix-clients-overview-diagram

7. Configure zabbix-agentd to use your just new brand new zabbix-proxy

Here is my sample configuration file:

[root@sysadminshelp:/etc/zabbix]# grep -v \# /etc/zabbix/zabbix_agentd.conf | sed '/^$/d'
PidFile=/var/run/zabbix/zabbix_agentd.pid
LogFile=/var/log/zabbix/zabbix_agentd.log
LogFileSize=0
Server=zabbix-proxy
ServerActive=zabbix-proxy:10051
ListenIP
Hostname=sysadminshelp
BufferSend=30
BufferSize=100
Include=/etc/zabbix/zabbix_agentd.d/*.conf


Note that the ServerActive given "zabbix-proxy" should be resolvable from the host, or even better you might want to put the IP of the Proxy if
you don't have at least a pseudo Hostname already configured inside /etc/hosts or actual DNS 'A' Active record configured inside a properly resolving
DNS server configured on the host via /etc/resolv.conf.


8. Create and Configure new proxy into the Zabbix-server host
 

Go to the zabbix server web interface URL into menus:

zabbix-administration-proxy-config
 

Administration -> Proxies (Proxy) 


Click on ;

Create Proxy button (uppper right corner)

*Proxy name: usually-your-host-pingable-fqdn
Proxy mode: Active
Proxy address: 192.168.1.50
Description: pcfreak zabbix proxy


Administration -> Proxies -> Encryption


From "Connection to proxy"

Untick "No encryption"

and

Tick "PSK"


zabbix-administration-proxy-config-encryption

*PSK Identity: PSK proxy
*PSK: Put the key here (copy from /etc/zabbix/zabbix_proxy.psk generated steps earlier with openssl)

[root@sysadminshelp:/etc/zabbix]# cat zabbix_proxy.psk
faddbd96be00ac42c892fda5201634df25d51f3ndbbbf6cee9d354b2817092a28

Press the "Update" Button

zabbix-administration-proxy-config-encryption1

and go again to Proxies and check the zabbix-proxy is connected to the server and hosts configured to use the zabbix proxy reporting frequently.

To make sure that the configured new hosts to use the Zabbix Proxy instead of direct connection to Zabbix Server, go to Latest Data and check whether the configured Hostnames to connect to the Zabbix-Proxy continues to sent Data still.

9. Debugging problems with zabix-proxy and zabbix-agentd connectivity to proxy

In case of troubles check out what is going on inside the Zabbix Proxy / Agent and Server log files
 

[root@sysadminshelp:/etc/zabbix]# tail -n 50 /var/log/zabbix/zabbix_proxy.log

 6832:20230504:134032.281 Starting Zabbix Proxy (active) [zabbix-proxy]. Zabbix 5.0.31 (revision f
64a07aefca).
  6832:20230504:134032.281 **** Enabled features ****
  6832:20230504:134032.281 SNMP monitoring:       YES
  6832:20230504:134032.281 IPMI monitoring:       YES
  6832:20230504:134032.281 Web monitoring:        YES
  6832:20230504:134032.281 VMware monitoring:     YES
  6832:20230504:134032.281 ODBC:                  YES
  6832:20230504:134032.281 SSH support:           YES
  6832:20230504:134032.281 IPv6 support:          YES
  6832:20230504:134032.281 TLS support:           YES
  6832:20230504:134032.281 **************************
  6832:20230504:134032.281 using configuration file: /etc/zabbix/zabbix_proxy.conf
  6832:20230504:134032.291 current database version (mandatory/optional): 05000000/05000005
  6832:20230504:134032.291 required mandatory version: 05000000
  6832:20230504:134032.292 proxy #0 started [main process]
  6833:20230504:134032.292 proxy #1 started [configuration syncer #1]
  6833:20230504:134032.329 received configuration data from server at "192.168.1.28", datalen 40521
  6834:20230504:134032.392 proxy #2 started [trapper #1]
  6835:20230504:134032.401 proxy #3 started [trapper #2]
  6836:20230504:134032.402 proxy #4 started [trapper #3]
  6838:20230504:134032.405 proxy #6 started [trapper #5]
  6837:20230504:134032.409 proxy #5 started [trapper #4]
  6843:20230504:134032.409 proxy #11 started [heartbeat sender #1]
  6845:20230504:134032.412 proxy #13 started [housekeeper #1]
  6847:20230504:134032.412 proxy #15 started [discoverer #1]
  8526:20230504:145836.512 proxy #20 started [history syncer #3]
  8517:20230504:145836.512 proxy #11 started [heartbeat sender #1]
  8530:20230504:145836.515 proxy #24 started [java poller #3]
  8531:20230504:145836.517 proxy #25 started [java poller #4]
  8532:20230504:145836.520 proxy #26 started [java poller #5]
  8536:20230504:145836.522 proxy #30 started [poller #1]
  8527:20230504:145836.525 proxy #21 started [history syncer #4]
  8535:20230504:145836.525 proxy #29 started [task manager #1]
  8533:20230504:145836.528 proxy #27 started [snmp trapper #1]
  8539:20230504:145836.528 proxy #33 started [poller #4]
  8538:20230504:145836.529 proxy #32 started [poller #3]
  8534:20230504:145836.532 proxy #28 started [self-monitoring #1]
  8544:20230504:145836.532 proxy #38 started [icmp pinger #1]
  8543:20230504:145836.532 proxy #37 started [unreachable poller #3]
  8542:20230504:145836.535 proxy #36 started [unreachable poller #2]
  8541:20230504:145836.537 proxy #35 started [unreachable poller #1]
  8540:20230504:145836.540 proxy #34 started [poller #5]
  8507:20230504:150036.453 received configuration data from server at "192.168.1.28", datalen 40521
  8507:20230504:150236.503 received configuration data from server at "192.168.1.28", datalen 40521
  8507:20230504:150436.556 received configuration data from server at "192.168.1.28", datalen 40521
  8507:20230504:150636.608 received configuration data from server at "192.168.1.28", datalen 40521
  8507:20230504:150836.662 received configuration data from server at "192.168.1.28", datalen 40521
…

 

[root@sysadminshelp:/etc/zabbix]# tail -n 10  /var/log/zabbix-agent/zabbix_agentd.log
3096166:20230504:182840.461 agent #1 started [collector]
3096167:20230504:182840.462 agent #2 started [listener #1]
3096168:20230504:182840.463 agent #3 started [listener #2]
3096169:20230504:182840.464 agent #4 started [listener #3]
3096170:20230504:182840.464 agent #5 started [active checks #1]

If necessery to Debug further and track some strange errors, you might want to increase the DebugLevel to lets say DebugLevel=5

5 – extended debugging (produces even more information)

If checking both zabbix_agentd.log and zabbix_proxy.log cannot give you enough of a hint on what might be the issues you face with your userparameter scripts or missing Monitored data etc. and hopefully you have access to the zabbix-server machine, check out the zabbix server log as well

[root@zabbix:~]# tail -n 100 /var/log/zabbix/zabbix_server.log

3145027:20230504:182641.556 sending configuration data to proxy "zabbix-proxy" at "192.168.1.50", datalen 40521, bytes 6120 with compression ratio 6.6
3145029:20230504:182716.529 cannot send list of active checks to "192.168.1.30": host [pcfrxenweb] not found
3145028:20230504:182731.959 cannot send list of active checks to "192.168.1.30": host [pcfrxenweb] not found
3145029:20230504:182756.634 cannot send list of active checks to "192.168.1.30": host [pcfrxenweb] not found

Wrapping it up

In this article, we have learned how to install and configure a zabbix-proxy server and prepare a PSK encryption secret key for it.
We learned also  how to connect this server to the central zabbix monitoring host machine in Active mode, so both Zabbix proxy and server can communicate in a secure crypted form,
as well as how to set zabbix_agentd clients to connect to the zabbix proxy
which will from itself send its data to the Central Zabbix server host as well as how to Debug and hopefully solve issues with communication between Zabbix client -> Zabbix Proxy -> Zabbix server.

I know this article, does not say anything revolutionary and there is plenty of posts online talking about how to run yourself a zabbix proxy and make in your home or corporate network,
but I thought to write it down as by writting it and reading a bit more on the topic of Zabbix Server / Proxy / Agent, that give myself a better overview on how this technologies work and such an article will give myself an easier step by step guide to follow,
in future when I have to configure Zabbix Environments for personal hobby or professionally for customers.
Hope you enjoyed. Cheers ! 🙂

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Posted in Linux, System Administration, Zabbix | 2 Comments »

Analyze disk space usage in Linux / BSD with du / find and filelight /qdirstat / baobab GUI disk usage analyzers to check what takes up your disk space on Unix like OSes

Friday, April 21st, 2023

linux-how-to-find-out-what-files-and-directories-has-occupied-all-your-disk-space-partition-from-console-and-GUI_du-find-filelight-baobab-qdirstat-duff-linux-450x450

If you're a Desktop Linux or BSD UNIX user and your hard disk / external SSD / flash drive etc. space starts to be misteriously disapper due to whatever reaseon such as a crashing applications producing rapidly log error / warning messages leading quickly to filling up the disk or out of a sudden you have some Disk space lost without knowing what kind of data filled up the disk or you're downloading some big sized bittorrent files forgotten in your bittorrent client or complete mirroring a large website and you suddenly get the result of root directory ( / ) getting fully or nearly filled up, then you definitely would want to check out what has disk activity has eaten up your disk space and leaing to OS and Aplication slow responsiveness.

For the Linux regular *nix user finding out what is filling the disk is a trivial task with with find / du -hsc * but as people have different habits to use find and du I'll show you the most common ways I use this two command line tools to identify disk space low issues for the sake of comparison.
Others who have better easier ways to do it are very welcome to share it with me in the comments.
 

1. Finding large files on hard disk with find Linux command tool
 

host:~# find /home -type f -printf "%s\t%p\n" | sort -n | tail -10
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-6.bin
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-7.bin
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-8.bin
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-9.bin
2815424080    /home/hipo/.thunderbird/h3dasfii.default\
/ImapMail/imap.gmail.com/INBOX
2925584895    /home/hipo/Documents/.git/\
objects/pack/pack-8590b069cad26ac0af7560fb42b51fa9bfe41050.pack
4336918067    /home/hipo/Games/Mames_4GB-compilation-best-arcade-games-of-your-14_04_2021.tar.gz
6109003776    /home/hipo/VirtualBox VMs/CentOS/CentOS.vdi
23599251456    /home/hipo/VirtualBox VMs/Windows 7/Windows 7.vdi
33913044992    /home/hipo/VirtualBox VMs/Windows 10/Windows 10.vdi

I use less rarely find on Desktops and more when I have to do some kind of data usage analysis on servers, of course for my Linux home computer and any other Linux desktop machines, or just a small incomprehensive analysis du cmd is much more appropriate to use.


2. Finding large files Megabyte occupying space files sorted in Megabytes and Gigas with du
 

  • Check main 10 files sorted in megabytes that are hanging in a directory

pcfkreak:~# du -hsc /home/hipo/*|grep 'M\s'|sort -rn|head -n 10
956M    /home/hipo/last_dump1.sql
711M    /home/hipo/hipod
571M    /home/hipo/from-thinkpad_r61
453M    /home/hipo/ultimate-edition-themes
432M    /home/hipo/metasploit-framework
355M    /home/hipo/output-upgrade.txt
333M    /home/hipo/Плот
209M    /home/hipo/Work-New.tar.gz
98M    /home/hipo/DOOM64
90M    /home/hipo/mp3

  • Get 10 top larges files in Gigabytes that are space hungry and eating up your space

pcfkreak:~# du -hsc /home/hipo/*|grep 'G\s'|sort -rn|head -n 10
156G    total
60G    /home/hipo/VirtualBox VMs
37G    /home/hipo/Downloads
18G    /home/hipo/Desktop
11G    /home/hipo/Games
7.4G    /home/hipo/ownCloud
7.1G    /home/hipo/Документи
4.6G    /home/hipo/music
2.9G    /home/hipo/root
2.8G    /home/hipo/Documents


If you want to still work on the console terminal but you don't want to type too much you can use ncdu (ncurses) text tool, install it with

# apt install –yes ncdu


https://www.pc-freak.net/images/ncdu-gnu-linux-debian-screenshot.png

 For the most lazy ones or complete Linux newbies that doesn't want to spend time typing / learing or using text commands or softwares you can also check what has eaten up your full disk space with GUI tools as well.

There are at least 3 tools to use to check in Graphical Interface what has occupied your disk space on Linux / BSD, I'm aware of:

3. Filelight GUI disk usage analysis Linux tool

For those using KDE or preferring a shiny GUI interface that will capture the eye, perhaps filelight would be the option of choice tool to get analysis sum of your directory sturctures and file use on the laptop or desktop *unix OS.

unix-desktop:~# apt-cache show filelight|grep -i description-en -A 7
Description-en: show where your diskspace is being used
 Filelight allows you to understand your disk usage by graphically
 representing your filesystem as a set of concentric, segmented rings.
 .
 It is like a pie-chart, but the segments nest, allowing you to see both
 which directories take up all your space, and which directories
 and files inside those directories are the real culprits.
Description-md5: 397ff9a469e07a772f22460c66b66875


To use it simply go ahead and install it with apt or yum / dnf or whatever Linux package manager your distro uses:

unix-desktop:~# apt-get install –yes filelight
…

filelight-show-where-disk-space-is-being-used-graphically-tool-linux

4. GNOME DIsk Usage Analyzer Baobab GUI tool

For those being a GNOME / Mate / Budgie / Cinnamon Graphical interface users baobab shold be the program to use as it uses the famous LibGD library.

unix-desktop:~# apt-cache show baobab|grep -i description-en -A10
Description-en: GNOME disk usage analyzer
 Disk Usage Analyzer is a graphical, menu-driven application to analyse
 disk usage in a GNOME environment. It can easily scan either the whole
 filesystem tree, or a specific user-requested directory branch (local or
 remote).
 .
 It also auto-detects in real-time any changes made to your home
 directory as far as any mounted/unmounted device. Disk Usage Analyzer
 also provides a full graphical treemap window for each selected folder.
Description-md5: 5f6072b89ebb1dc83433fa7658814dc6
Homepage: https://wiki.gnome.org/Apps/Baobab
 

gnome-disk-analyzer-baobab-tool-screenshot-of-hard-disk-directory-locations-sorted-by-size

5. Qdirstat graphical application to show where your disk space has gone on Linux

Qdirstat is perhaps well known tool to track disk space issues on Linux desktop hosts, known by the hardcore KDE / LXDE / LXQT / DDE GUI interface / environment lovers and as a KDE tool uses the infamous Qt library. I personally don't like it and don't put it on machines I use because I never use kde and don't want to waste my disk space with additional libraries such as the QT Library which historically was not totally free in terms of licensing and even now is in both free and non free licensing GPL / LGPL and QT Commercial Licensing license.

unix-desktop:~# apt-cache show qdirstat|grep -i description-en -A10
Description-en: Qt-based directory statistics
 QDirStat is a graphical application to show where your disk space has gone and
 to help you to clean it up.
 .
 QDirStat has a number of new features compared to KDirStat. To name a few:
  * Multi-selection in both the tree and the treemap.
  * Unlimited number of user-defined cleanup actions.
  * Properly show errors of cleanup actions (and their output, if desired).
  * File categories (MIME types) and their treemap color are now configurable.
  * Exclude rules for directories are easily configurable.
  * Desktop-agnostic; no longer relies on KDE or any other specific desktop.


qdirstat-linux-screenshot-show-what-directory-uses-most-hard-disk-space

That shiny fuzed graphics is actually a repsesantation of all directories the bigger and if one scrolls on the colorful gamma a text with directory and size or file will appear. Though the graphical represantation is really c00l to me it is a bit unreadable, thus I prefer and recommend the other two GUI tools filelight or baobab instead.

6. Finding duplicate files on Linux system with duff command tool

Talking about big unknown left-over files on your hard drives, it is appropriate to mention one tool here that is a console one but very useful to anyone willing to get rid of old duplicate files that are hanging around on the disk. Sometimes such copies are produced while copying large amount of files from place to place or simply by mistake while copying Photo / Video files from your Smart Phone to Linux desktop etc. 

This is where the duff command line utility might be super beneficial for you.

unix-desktop:~# apt-cache show duff|grep -i description-en -A3
Description-en: Duplicate file finder
 Duff is a command-line utility for identifying duplicates in a given set of
 files.  It attempts to be usably fast and uses the SHA family of message
 digests as a part of the comparisons.

Using duff tool is very straight forward to see all the duplicate files hanging in a directory lets say your home folder.

unix-desktop:~#  duff -rP /home/hipo
…

/home/hipo/music/var/Quake II Soundtrack – Kill Ratio.mp3
/home/hipo/mp3/Quake II Soundtrack – Kill Ratio.mp3
2 files in cluster 44 (7913472 bytes, digest 98f38be49e2ffcbf90927f9357b3e24a81d5a649)
/home/hipo/music/var/HYPODIL_01-Scakauec.mp3
/home/hipo/mp3/HYPODIL_01-Scakauec.mp3
2 files in cluster 45 (2807808 bytes, digest ce9067ce1f132fc096a5044845c7fac73e99c0ed)
/home/hipo/music/var/Quake II Suondtrack – March Of The Stoggs.mp3
/home/hipo/mp3/Quake II Suondtrack – March Of The Stoggs.mp3
2 files in cluster 46 (3506176 bytes, digest efcc401b4ebda9b0b2367aceb8e334c8ba1a357d)
/home/hipo/music/var/Quake II Suondtrack – Quad Machine.mp3
/home/hipo/mp3/Quake II Suondtrack – Quad Machine.mp3
2 files in cluster 47 (7917568 bytes, digest 0905c1d790654016c2ecf2949f78d47a870c3822)
/home/hipo/music/var/Cyberpunk Group – Futureshock!.mp3
/home/hipo/mp3/Cyberpunk Group – Futureshock!.mp3

-r (Recursively search into all specified directories.)

–P (Don't follow any symbolic links.  This overrides any previous -H or -L option.  This is the default.  Note that this only applies to directories, as sym‐
             bolic links to files are never followed.)

7. Deleting duplicate files with duff

If you're absolutely sure you know what you're doing and you have a backup in case if something messes up during duplicate teletions, to get rid of lets say any duplicate Picture files found by duff run sommething like:

# duff -e0 -r /home/hipo/Pictures/ | xargs -0 rm

!!! Please note that using duff is for those who absolutely know what they're doing and have their data recent data. Deleting the wrong data by mistake with the tool might put you in the first grade and you'll be the only one to blame  🙂 !!!

Wrap it Up

Filling up the disk with unknown large files is a task to resolve that happens often. For the unlazy on Linux / BSD / Mac OS and other UNIX like OS-es the easiest way is to use find or du with some one liner command. For the lazy Windows addicted Graphical users filelight, qdirstat or baobab GUI disk usage analysis tools are there.
If you have a lot of files and many of thems are duplicates you can use duff to check them out and remove all unneded duplicates and save space. 
Hope this article, was helpful for someone.
That's all folks, enjoy your data profilactics, if you know any other good easy command or GUI tools or hints for drive disk space profilactics please share.

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