Archive for the ‘System Administration’ Category

« Older Entries

How to set up Notify by email expiring local UNIX user accounts on Linux / BSD with a bash script

Thursday, August 24th, 2023

password-expiry-linux-tux-logo-script-picture-how-to-notify-if-password-expires-on-unix

If you have already configured Linux Local User Accounts Password Security policies Hardening – Set Password expiry, password quality, limit repatead access attempts, add directionary check, increase logged history command size and you want your configured local user accounts on a Linux / UNIX / BSD system to not expire before the user is reminded that it will be of his benefit to change his password on time, not to completely loose account to his account, then you might use a small script that is just checking the upcoming expiry for a predefined users and emails in an array with lslogins command like you will learn in this article.

The script below is written by a colleague Lachezar Pramatarov (Credit for the script goes to him) in order to solve this annoying expire problem, that we had all the time as me and colleagues often ended up with expired accounts and had to bother to ask for the password reset and even sometimes clearance of account locks. Hopefully this little script will help some other unix legacy admin systems to get rid of the account expire problem.

For the script to work you will need to have a properly configured SMTP (Mail server) with or without a relay to be able to send to the script predefined email addresses that will get notified. 

Here is example of a user whose account is about to expire in a couple of days and who will benefit of getting the Alert that he should hurry up to change his password until it is too late 🙂

[root@linux ~]# date
Thu Aug 24 17:28:18 CEST 2023

[root@server~]# chage -l lachezar
Last password change                                    : May 30, 2023
Password expires                                        : Aug 28, 2023
Password inactive                                       : never
Account expires                                         : never
Minimum number of days between password change          : 0
Maximum number of days between password change          : 90
Number of days of warning before password expires       : 14

Here is the user_passwd_expire.sh that will report the user

# vim  /usr/local/bin/user_passwd_expire.sh

#!/bin/bash

# This script will send warning emails for password expiration 
# on the participants in the following list:
# 20, 15, 10 and 0-7 days before expiration
# ! Script sends expiry Alert only if day is Wednesday – if (( $(date +%u)==3 )); !

# email to send if expiring
alert_email='alerts@pc-freak.net';
# the users that are admins added to belong to this group
admin_group="admins";
notify_email_header_customer_name='Customer Name';

declare -A mails=(
# list below accounts which will receive account expiry emails

# syntax to define uid / email
# [“account_name_from_etc_passwd”]="real_email_addr@fqdn";

#    [“abc”]="abc@fqdn.com"
#    [“cba”]="bca@fqdn.com"
    [“lachezar”]="lachezar.user@gmail.com"
    [“georgi”]="georgi@fqdn-mail.com"
    [“acct3”]="acct3@fqdn-mail.com"
    [“acct4”]="acct4@fqdn-mail.com"
    [“acct5”]="acct5@fqdn-mail.com"
    [“acct6”]="acct6@fqdn-mail.com"
#    [“acct7”]="acct7@fqdn-mail.com"
#    [“acct8”]="acct8@fqdn-mail.com"
#    [“acct9”]="acct9@fqdn-mail.com"
)

declare -A days

while IFS="=" read -r person day ; do
  days[“$person”]="$day"
done < <(lslogins –noheadings -o USER,GROUP,PWD-CHANGE,PWD-WARN,PWD-MIN,PWD-MAX,PWD-EXPIR,LAST-LOGIN,FAILED-LOGIN  –time-format=iso | awk '{print "echo "$1" "$2" "$3" $(((($(date +%s -d \""$3"+90 days\")-$(date +%s)))/86400)) "$5}' | /bin/bash | grep -E " $admin_group " | awk '{print $1 "=" $4}')

#echo ${days[laprext]}
for person in "${!mails[@]}"; do
     echo "$person ${days[$person]}";
     tmp=${days[$person]}

#     echo $tmp
# each person will receive mails only if 20th days / 15th days / 10th days remaining till expiry or if less than 7 days receive alert mail every day

     if  (( (${tmp}==20) || (${tmp}==15) || (${tmp}==10) || ((${tmp}>=0) && (${tmp}<=7)) )); 
     then
         echo "Hello, your password for $(hostname -s) will expire after ${days[$person]} days.” | mail -s “$notify_email_header_customer_name $(hostname -s) server password expiration”  -r passwd_expire ${mails[$person]};
     elif ((${tmp}<0));
     then
#          echo "The password for $person on $(hostname -s) has EXPIRED before{days[$person]} days. Please take an action ASAP.” | mail -s “EXPIRED password of  $person on $(hostname -s)”  -r EXPIRED ${mails[$person]};

# ==3 meaning day is Wednesday the day on which OnCall Person changes

        if (( $(date +%u)==3 ));
        then
             echo "The password for $person on $(hostname -s) has EXPIRED. Please take an action." | mail -s "EXPIRED password of  $person on $(hostname -s)"  -r EXPIRED $alert_email;
        fi
     fi  
done
 


To make the script notify about expiring user accounts, place the script under some directory lets say /usr/local/bin/user_passwd_expire.sh and make it executable and configure a cron job that will schedule it to run every now and then.

# cat /etc/cron.d/passwd_expire_cron

# /etc/cron.d/pwd_expire
#
# Check password expiration for users
#
# 2023-01-16 LPR
#
02 06 * * * root /usr/local/bin/user_passwd_expire.sh >/dev/null

Script will execute every day morning 06:02 by the cron job and if the day is wednesday (3rd day of week) it will send warning emails for password expiration if 20, 15, 10 days are left before account expires if only 7 days are left until the password of user acct expires, the script will start sending the Alarm every single day for 7th, 6th … 0 day until pwd expires.

If you don't have an expiring accounts and you want to force a specific account to have a expire date you can do it with:

# chage -E 2023-08-30 someuser


Or set it for new created system users with:

# useradd -e 2023-08-30 username


That's it the script will notify you on User PWD expiry.

If you need to for example set a single account to expire 90 days from now (3 months) that is a kind of standard password expiry policy admins use, do it with:

# date -d "90 days" +"%Y-%m-%d"
2023-11-22


Ideas for user_passwd_expire.sh script improvement
 

The downside of the script if you have too many local user accounts is you have to hardcode into it the username and user email_address attached to and that would be tedios task if you have 100+ accounts. 

However it is pretty easy if you already have a multitude of accounts in /etc/passwd that are from UID range to loop over them in a small shell loop and build new array from it. Of course for a solution like this to work you will have to have defined as user data as GECOS with command like chfn.
 

[georgi@server ~]$ chfn
Changing finger information for test.
Name [test]: 
Office []: georgi@fqdn-mail.com
Office Phone []: 
Home Phone []: 

Password: 

[root@server test]# finger georgi
Login: georgi                       Name: georgi
Directory: /home/georgi                   Shell: /bin/bash
Office: georgi@fqdn-mail.com
On since чт авг 24 17:41 (EEST) on :0 from :0 (messages off)
On since чт авг 24 17:43 (EEST) on pts/0 from :0
   2 seconds idle
On since чт авг 24 17:44 (EEST) on pts/1 from :0
   49 minutes 30 seconds idle
On since чт авг 24 18:04 (EEST) on pts/2 from :0
   32 minutes 42 seconds idle
New mail received пт окт 30 17:24 2020 (EET)
     Unread since пт окт 30 17:13 2020 (EET)
No Plan.

Then it should be relatively easy to add the GECOS for multilpe accounts if you have them predefined in a text file for each existing local user account.

Hope this script will help some sysadmin out there, many thanks to Lachezar for allowing me to share the script here.
Enjoy ! 🙂

Tags: , , , , , , , , , , , , ,
Posted in Bash Scripting, Educational, Linux, Linux and FreeBSD Desktop, Security, System Administration | No Comments »

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.

Tags: , , , , , , , , , , , , , , , ,
Posted in Linux, Monitoring, System Administration, Zabbix | No Comments »

Unfreeze stucked “freezed” messages from Exim Mail server queue

Friday, June 16th, 2023

how-to-unfreeze-messages-from-exim-mail-server-smtp-logo-linux-and-some-other-useful-exim-commands.png

Messages are frozen when the mail server has determined it cannot do anything to deliver the message. (they can also be manually frozen).

Exim has option to set how long frozen messages are kept on the system.

On a Debian/Ubuntu based install the /etc/exim4/conf.d/main/02_exim4-config_options file has the option timeout_frozen_after = 7d. Which means messages frozen for 7 days will get expunged.

Frozen messages really shouldn't be a problem on most systems. They are often just spam messages that can't get properly delivered.

If you have to deal with freezed mails from the exim mail server, unlike postfix, where there is no "freeze" scheme but the messages just stuck in the queue and you might want to simply ask the mail server to resend failed to deliver messages once again through a simple:

# postqueue -f


With exim to ask the server to resend the freeze-d states messages there is another aproach:

It is for this reason that I am writing this post to share how you can ask the exim to resend the "frozen" messages, as on exim there is no so much straight forward way.

To find out what letters are stored in the exim queue run

# exim -bp

To unfreeze the messages a simple while loop can be written, which lists all frozen state messages and unfreezes these letters one by one in a cycle:

# exim -bp | grep -i frozen | awk '{print $3}' | while read LINE; do exim -Mt $LINE; done

Another approach to unfreeze the frozen multitude of messages which should be a bit quicker if you have to do it for a very large amount of frozen states mails is to use xargs command:

# mailq | grep frozen | awk '{print $3}' | xargs exim -v -M

Since we on exim topic in this article, for starters with Exim, here is few other useful exim queue commands, that might be beneficial if you have to deal with EXIM SMTP.

Attempting to send a mail with a specified ID

# /usr/sbin/exim -M email-id


Forcefully run another queue to execute

# /usr/sbin/exim -qf

We see the logs related to letter

# /usr/sbin/exim -Mvl messageID

To see the body of the letter

# /usr/sbin/exim -Mvb messageID

To see the beginning (header) of the letter only

# /usr/sbin/exim -Mvh messageID

Deletes the mail without sending any error messages

# /usr/sbin/exim -Mrm messageID

Shows the number of letters in the queue

# /usr/sbin/exim -bpr | grep "<" | wc -l

Shows the number of frozen mails in the queue

# /usr/sbin/exim -bpr | grep frozen | wc -l

Deletes all frozen letters

# /usr/sbin/exim -bpr | grep frozen | awk {'print $3'} | xargs exim -Mrm

To remove a message from the Exim queue

# exim -Mrm {message-id}

Remove all messages from the Exim queue

# exim -bp | awk '/^ *[0-9]+[mhd]/{print "exim -Mrm " $3}' | bash

Another way to do it:

# exim -bp | exiqgrep -i | xargs exim -Mrm


Fastest solution to delete all emails in exim queue (for less than 5 seconds) is
 

# cd /var/spool
# mv exim exim.old
# mkdir -p exim/input
# mkdir -p exim/msglog
# mkdir -p exim/db
# chown -R mail:mail exim
# /sbin/service exim restart

or if you have AV / AntiSpam integrated to mail server:

# cd /var/spool
# mv exim exim.old
# mkdir -p exim/db
# mkdir -p exim/input
# mkdir -p exim/msglog
# mkdir -p exim/scan
# chown -R mail:mail exim
# /sbin/service exim restart

Deletes the entire exim queue

# /usr/sbin/exim -qff

Tags: , , , , , , , , ,
Posted in System Administration | No Comments »

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 | No 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 ! 🙂

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Linux, System Administration, Zabbix | No Comments »

Monitor cluster heartbeat lines IP reahability via ping ICMP protocol with Zabbix

Wednesday, April 12th, 2023

https://pc-freak.net/images/zabbix-monitoring-icmp-ping-on-application-crm-clusters-with-userparameter-script-howto

Say you're having an haproxy load balancer cluster with two or more nodes and you are running the servers inside some complex organizational hybrid complex network that is a combination of a local DMZ lans, many switches, dedicated connectivity lines and every now and then it happens for the network to mysteriously go down. Usually simply setting monitoring on the network devices CISCO itself or the smart switches used is enough to give you an overview on what's going on but if haproxy is in the middle of the end application servers and in front of other Load balancers and network equipment sometimes it might happen that due to failure of a network equipment / routing issues or other strange unexpected reasons one of the 2 nodes connectivity might fail down via the configured dedicated additional Heartbeat lines that are usually configured in order to keep away the haproxy CRM Resource Manager cluster thus ending it up in a split brain scenarios.

Assuming that this is the case like it is with us you would definitely want to keep an eye on the connectivity of Connect Line1 and Connect Line2 inside some monitoring software like zabbix. As our company main monitoring software used to monitor our infrastructure is Zabbix in this little article, I'll briefly explain how to configre the network connectivity status change from haproxy node1 and haproxy node2 Load balancer cluster to be monitored via a simple ICMP ping echo checks.

Of course the easies way to configure an ICMP monitor via Zabbix is using EnableRemoteCommands=1 inside /etc/zabbix/zabbix-agentd.conf but if your infrastructure should be of High Security and PCI perhaps this options is prohibited to be used on the servers. This is why to achieve still the ICMP ping checks with EnableRemoteCommands=0 a separate simple bash user parameter script could be used. Read further to find out one way ICMP monitoring with a useparameter script can be achieved with Zabbix.


1. Create the userparameter check for heartbeat lines

root@haproxy1 zabbix_agentd.d]# cat userparameter_check_heartbeat_lines.conf
UserParameter=heartbeat.check,\
/etc/zabbix/scripts/check_heartbeat_lines.sh

root@haproxy2 zabbix_agentd.d]# cat userparameter_check_heartbeat_lines.conf
UserParameter=heartbeat.check,\
/etc/zabbix/scripts/check_heartbeat_lines.sh

2. Create check_heartbeat_lines.sh script which will be actually checking connectivity with simple ping

root@haproxy1 zabbix_agentd.d]# cat /etc/zabbix/scripts/check_heartbeat_lines.sh
#!/bin/bash
hb1=haproxy2-lb1
hb2=haproxy2-lb2
if ping -c 1 $hb1  &> /dev/null
then
  echo "$hb1 1"
else
  echo "$hb1 0"
fi
if ping -c 1 $hb2  &> /dev/null
then
  echo "$hb2 1"
else
  echo "$hb2 0"
fi
[root@haproxy1 zabbix_agentd.d]#

root@haproxy2 zabbix_agentd.d]# cat /etc/zabbix/scripts/check_heartbeat_lines.sh
#!/bin/bash
hb1=haproxy1-hb1
hb2=haproxy1-hb2
if ping -c 1 $hb1  &> /dev/null
then
  echo "$hb1 1"
else
  echo "$hb1 0"
fi
if ping -c 1 $hb2  &> /dev/null
then
  echo "$hb2 1"
else
  echo "$hb2 0"
fi
[root@haproxy2 zabbix_agentd.d]#


3. Test script heartbeat lines first time

Each of the nodes from the cluster are properly pingable via ICMP protocol

The script has to be run on both haproxy1 and haproxy2 Cluster (load) balancer nodes

[root@haproxy-hb1 zabbix_agentd.d]# /etc/zabbix/scripts/check_heartbeat_lines.sh
haproxy2-hb1 1
haproxy2-hb2 1

[root@haproxy-hb2 zabbix_agentd.d]# /etc/zabbix/scripts/check_heartbeat_lines.sh
haproxy1-hb1 1
haproxy1-hb2 1


The status of 1 returned by the script should be considered remote defined haproxy node is reachable / 0 means ping command does not return any ICMP status pings back.

4. Restart the zabbix-agent on both cluster node machines that will be conducting the ICMP ping check

[root@haproxy zabbix_agentd.d]# systemctl restart zabbix-agentd
[root@haproxy zabbix_agentd.d]# systemctl status zabbix-agentd
…
[root@haproxy zabbix_agentd.d]# tail -n 100 /var/log/zabbix_agentd.log
…


5. Create Item to process the userparam script

Create Item as follows:

6. Create the Dependent Item required
 

zabbix-heartbeat-check-screenshots/heartbeat-line1-preprocessing

For processing you need to put the following simple regular expression

Name: Regular Expression
Parameters: hb1(\s+)(\d+)
Custom on fail: \2

zabbix-heartbeat-check-screenshots/heartbeat-line2-preprocessing1

zabbix-heartbeat-check-screenshots/heartbeat-lines-triggers

 

7. Create triggers that will be generating the Alert

Create the required triggers as well

zabbix-heartbeat-check-screenshots/heartbeat2-line
Main thing to configure here in Zabbix is below expression

Expression: {FQDN:heartbeat2.last()}<1

triggers_heartbeat1

You can further configure Zabbix Alerts to mail yourself or send via Slack / MatterMost or Teams alarms in case of problems.

Tags: , , , , , , , , , , , , , , ,
Posted in Monitoring, System Administration, Zabbix | No Comments »

Enable PSK encryption on Zabbix Agent (client) sent encrypted monitored datas to Zabbix server

Friday, April 7th, 2023

zabbix-client-server-encryption-public-key-exchange

Those concerned of security and in use of their Zabbix monitored data who communicate Zabbix collected agent
data over internet or via some kind of untrusted network might definitely not enjoy the fact that zabbix-agent sents
its collected data to server in a plain text. Clear text data is allowing any network sniffer to possibly collect your
monitored server and hardware devices data and exposes all data sent over the network to same problems like in the past
the old uencrypted SMTP protocol.

To mitigate those great security hole for the paranoid sys admin it is rather easy to enable PSK (Pre Shared Key) based encryption.
To generate Pre Shared key you have to had to important values present

1. PSK Identity
2. PSK Secret

PSK secret should be minimum of 128 bit (16-byte PSK, entered as 32 hexadecimal digits), and supports up to
2048 bit (256-byte PSK, entered as 512 hexadecimal digits)

Usually something like 256 bit PSK secret on the machine should be strong enough and simply generated by running

# openssl rand -hex 32

1. Agent to zabbix server or proxy connection config

In /etc/zabbix/zabbix_agentd.conf for a Server Active (e.g. server to actively request the client to sent its collected data)
On machine running zabbix-agent should have a configuration similar to:

# cat /etc/zabbix/zabbix_agentd.conf

PidFile=/var/run/zabbix/zabbix_agentd.pid
LogFile=/var/log/zabbix/zabbix_agentd.log
LogFileSize=0

# IP of the machine
SourceIP=10.10.10.30
# turn it on if you need to execute to remote machine commands
EnableRemoteCommands=0

# IP of the server
servers=10.30.50.80
ListenPort=10080

# IP of the machine
ListenIP=10.30.30.31

# IP of the server
ServerActive=10.30.50.80

HostMetadataItem=system.uname
BufferSize=5400
MaxLinesPerSecond=5
Timeout=10
AllowRoot=0
StartAgents=5
LogRemoteCommands=0


# Machine hostname
Hostname=fqdn-of-zabbix-data-collect-server.com
Include=/etc/zabbix/zabbix_agentd.d/*.conf

# Encryption
TLSConnect=psk
TLSAccept=psk
TLSPSKIdentity=PSK to Zabbix Server5
TLSPSKFile=/etc/zabbix/zabbix_agentd.psk


! Important security note

!!! The TLSPSKIdentity value you decide will not be encrypted on transport, so don't use anything sensitive.

Once you include the TSL config

2 Generate / Create Zabbix Agent Key

Generate the key with pseudo-random bites inside /etc/zabbix/zabbix_agentd_key.psk

# cd /etc/zabbix
# openssl rand -hex 32 > zabbix_agentd_key.psk
# chown zabbix:zabbix zabbix_agentd_key.psk
# chmod 600 zabbix_agentd_key.psk

3. Configure PSK encryption in Zabbix Server Web User interface

Go to Zabbix Server User interface in browser and configure the PSK encryption options for the host.

Select the:

'Connections to host' = PSK

'Connections from host' = PSK

'PSK Identity' = [public-value-configured-in-Zabbix-agent-config]

'PSK' = [paste the long hex string generated from the OpenSSL command above]


In some seconds up to a minute or two the Zabbix Server and Agent will successfully communicate using PSK encryption.
Making the monitored data unreadable in plain text for malignant sniffers hanging in the middle equipment between the zabbix-agent and zabbix-server hosts.

4. PSK encryption behind a Proxy

Many companies, nowadays use zabbix proxy for improvement of network infrastrucutre. For example it is used to offload the zabbix-server when multiple zabbix-agents have to report various datas or to monitor servers and devices that are phyisically in separate networks or data centers (are passing through paranoic built firewalls) or monitor locations are having unreliable communications between each other.
 

To enable PSK for communications between your Zabbix Server and Zabbix Proxy.

1. Create a new secret, and add the PSK Identity and Secret to

Administration ⇾ Proxies ⇾ [Your proxy] ⇾ Encryption

2. Adjust the settings inside the zabbix proxies configuration file at /etc/zabbix/zabbix_proxy.conf


If setting up PSK encryption for agents behind a Zabbix proxy, ensure your have

Zabbix Server ⇽⇾ Proxy PSK enabled
first in Zabbix Server UI.

This is because, when you start the Proxy, or do some testing to send some key value to Zabbix server via the proxy with commands :

# zabbix_get -s 127.0.0.1 -k system.hostname
# zabbix_server -R config_cache_reload


config_cache_reload, the Proxy will download all its host settings from the server, and this also includes the servers copy of the secret.

The proxy needs to know the secret since it is now managing the communications on behalf of the server.

3. To add PSK encryption for any Agents behind a proxy, then you continue to set up the Agents as normal by creating a new secret, editing

Configuration ⇾ Hosts ⇾ [Your Host] ⇾ Encryption page

and also editing /etc/zabbix/zabbix_agentd.conf.

Remember that, since your Agents Host configuration in the Zabbix UI will be set as Monitored by Proxy, the PSK settings will be applicable for communications happening between the Zabbix Proxy and the Agent that it is monitoring, not between the Zabbix Server and the Agent behind the proxy.

You can also add PSK Encryption between your Zabbix Proxy and its own local Agent if you want.
You would set its PSK settings in the Proxy Agents host configuration at

Configuration ⇾ Hosts ⇾ [Your proxy] ⇾ Encryption

and modify the settings in the agents on configuration file at /etc/zabbix/zabbix_agentd.conf.
Keep in mind, this is only applicable to communications between the Zabbix Proxy, and its own Agent process.

When setting up PSK encryption for the Zabbix Server, Proxy and Agents, you may see an error in the Proxy logs,

cannot send proxy data to server at "zabbix.your-domain.tld": connection of type "TLS with PSK" is not allowed for proxy "your-proxy".

If you hit this, check that your

Zabbix Server ⇽⇾ Proxy PSK settings

are correct first.

Don't get confused between the Proxies own optional agent process, and its main Proxy process which is required.

Tags: , , , , , , , , , , , , ,
Posted in Computer Security, Linux, Monitoring, System Administration, Zabbix | No Comments »

Configure aide file integrity check server monitoring in Zabbix to track for file changes on servers

Tuesday, March 28th, 2023

zabbix-aide-log-monitoring-logo

Earlier I've written a small article on how to setup AIDE monitoring for Server File integrity check on Linux, which put the basics on how this handy software to improve your server overall Security software can be installed and setup without much hassle.

Once AIDE is setup and a preset custom configuration is prepared for AIDE it is pretty useful to configure AIDE to monitor its critical file changes for better server security by monitoring the AIDE log output for new record occurs with Zabbix. Usually if no files monitored by AIDE are modified on the machine, the log size will not grow, but if some file is modified once Advanced Linux Intrusion Detecting (aide) binary runs via the scheduled Cron job, the /var/log/app_aide.log file will grow zabbix-agentd will continuously check the file for size increases and will react.

Before setting up the Zabbix required Template, you will have to set few small scripts that will be reading a preconfigured list of binaries or application files etc. that aide will monitor lets say via /etc/aide-custom.conf
 

1. Configure aide to monitor files for changes


Before running aide, it is a good idea to prepare a file with custom defined directories and files that you plan to monitor for integrity checking e.g. future changes with aide, for example to capture bad intruders who breaks into server which runs aide and modifies critical files such as /etc/passwd /etc/shadow /etc/group or / /usr/local/etc/* or /var/* / /usr/* critical files that shouldn't be allowed to change without the admin to soon find out.

# cat /etc/aide-custom.conf

# Example configuration file for AIDE.
@@define DBDIR /var/lib/aide
@@define LOGDIR /var/log/aide
# The location of the database to be read.
database=file:@@{DBDIR}/app_custom.db.gz
database_out=file:@@{DBDIR}/app_aide.db.new.gz
gzip_dbout=yes
verbose=5

report_url=file:@@{LOGDIR}/app_custom.log
#report_url=syslog:LOG_LOCAL2
#report_url=stderr
#NOT IMPLEMENTED report_url=mailto:root@foo.com
#NOT IMPLEMENTED report_url=syslog:LOG_AUTH

# These are the default rules.
#
#p:      permissions
#i:      inode:
#n:      number of links
#u:      user
#g:      group
#s:      size
#b:      block count
#m:      mtime
#a:      atime
#c:      ctime
#S:      check for growing size
#acl:           Access Control Lists
#selinux        SELinux security context
#xattrs:        Extended file attributes
#md5:    md5 checksum
#sha1:   sha1 checksum
#sha256:        sha256 checksum
#sha512:        sha512 checksum
#rmd160: rmd160 checksum
#tiger:  tiger checksum

#haval:  haval checksum (MHASH only)
#gost:   gost checksum (MHASH only)
#crc32:  crc32 checksum (MHASH only)
#whirlpool:     whirlpool checksum (MHASH only)

FIPSR = p+i+n+u+g+s+m+c+acl+selinux+xattrs+sha256

#R:             p+i+n+u+g+s+m+c+acl+selinux+xattrs+md5
#L:             p+i+n+u+g+acl+selinux+xattrs
#E:             Empty group
#>:             Growing logfile p+u+g+i+n+S+acl+selinux+xattrs

# You can create custom rules like this.
# With MHASH…
# ALLXTRAHASHES = sha1+rmd160+sha256+sha512+whirlpool+tiger+haval+gost+crc32
ALLXTRAHASHES = sha1+rmd160+sha256+sha512+tiger
# Everything but access time (Ie. all changes)
EVERYTHING = R+ALLXTRAHASHES

# Sane, with multiple hashes
# NORMAL = R+rmd160+sha256+whirlpool
NORMAL = FIPSR+sha512

# For directories, don't bother doing hashes
DIR = p+i+n+u+g+acl+selinux+xattrs

# Access control only
PERMS = p+i+u+g+acl+selinux

# Logfile are special, in that they often change
LOG = >

# Just do sha256 and sha512 hashes
LSPP = FIPSR+sha512

# Some files get updated automatically, so the inode/ctime/mtime change
# but we want to know when the data inside them changes
DATAONLY =  p+n+u+g+s+acl+selinux+xattrs+sha256

##############TOUPDATE
#To delegate to app team create a file like /app/aide.conf
#and uncomment the following line
#@@include /app/aide.conf
#Then remove all the following lines
/etc/zabbix/scripts/check.sh FIPSR
/etc/zabbix/zabbix_agentd.conf FIPSR
/etc/sudoers FIPSR
/etc/hosts FIPSR
/etc/keepalived/keepalived.conf FIPSR
# monitor haproxy.cfg
/etc/haproxy/haproxy.cfg FIPSR
# monitor keepalived
/home/keepalived/.ssh/id_rsa FIPSR
/home/keepalived/.ssh/id_rsa.pub FIPSR
/home/keepalived/.ssh/authorized_keys FIPSR
/usr/local/bin/script_to_run.sh FIPSR
/usr/local/bin/another_script_to_monitor_for_changes FIPSR

#  cat /usr/local/bin/aide-config-check.sh
#!/bin/bash
/sbin/aide -c /etc/aide-custom.conf -D

# cat /usr/local/bin/aide-init.sh
#!/bin/bash
/sbin/aide -c /etc/custom-aide.conf -B database_out=file:/var/lib/aide/custom-aide.db.gz -i

 

# cat /usr/local/bin/aide-check.sh

#!/bin/bash
/sbin/aide -c /etc/custom-aide.conf -Breport_url=stdout -B database=file:/var/lib/aide/custom-aide.db.gz -C|/bin/tee -a /var/log/aide/custom-aide-check.log|/bin/logger -t custom-aide-check-report
/usr/local/bin/aide-init.sh

 

# cat /usr/local/bin/aide_app_cron_daily.txt

#!/bin/bash
#If first time, we need to init the DB
if [ ! -f /var/lib/aide/app_aide.db.gz ]
   then
    logger -p local2.info -t app-aide-check-report  "Generating NEW AIDE DATABASE for APPLICATION"
    nice -n 18 /sbin/aide –init -c /etc/aide_custom.conf
    mv /var/lib/aide/app_aide.db.new.gz /var/lib/aide/app_aide.db.gz
fi

nice -n 18 /sbin/aide –update -c /etc/aide_app.conf
#since the option for syslog seems not fully implemented we need to push logs via logger
/bin/logger -f /var/log/aide/app_aide.log -p local2.info -t app-aide-check-report
#Acknoledge the new database as the primary (every results are sended to syslog anyway)
mv /var/lib/aide/app_aide.db.new.gz /var/lib/aide/app_aide.db.gz

What above cron job does is pretty simple, as you can read it yourself. If the configuration predefined aide database store file /var/lib/aide/app_aide.db.gz, does not
exists aide will create its fresh empty database and generate a report for all predefined files with respective checksums to be stored as a comparison baseline for file changes. 

Next there is a line to write aide file changes via rsyslog through the logger and local2.info handler


2. Setup Zabbix Template with Items, Triggers and set Action

2.1 Create new Template and name it YourAppName APP-LB File integrity Check

aide-itengrity-check-zabbix_ Configuration of templates

Then setup the required Items, that will be using zabbix's Skip embedded function to scan file in a predefined period of file, this is done by the zabbix-agent that is
supposed to run on the server.

2.2 Configure Item like

aide-zabbix-triggers-screenshot
 

*Name: check aide log file

Type: zabbix (active)

log[/var/log/aide/app_aide.log,^File.*,,,skip]

Type of information: Log

Update Interval: 30s

Applications: File Integrity Check

Configure Trigger like

Enabled: Tick On

images/aide-zabbix-screenshots/check-aide-log-item


2.3 Create Triggers with the respective regular expressions, that would check the aide generated log file for file modifications


aide-zabbix-screenshot-minor-config

Configure Trigger like
 

Enabled: Tick On


*Name: Someone modified {{ITEM.VALUE}.regsub("(.*)", \1)}

*Expression: {PROD APP-LB File Integrity Check:log[/var/log/aide/app_aide.log,^File.*,,,skip].strlen()}>=1

Allow manual close: yes tick

*Description: Someone modified {{ITEM.VALUE}.regsub("(.*)", \1)} on {HOST.NAME}

 

2.4 Configure Action

 

aide-zabbix-file-monitoring-action-screensho

Now assuming the Zabbix server has  a properly set media for communication and you set Alerting rules zabbix-server can be easily set tosend mails to a Support email to get Notifications Alerts, everytime a monitored file by aide gets changed.

That's all folks ! Enjoy being notified on every file change on your servers  !
 

Tags: , , , , , , , , , , , , , , , , , , , , ,
Posted in Computer Security, Linux, System Administration, Zabbix | No Comments »

How to log every Linux executed command by every running system program to separte log via rsyslog for better server Security and audit trails

Wednesday, March 15th, 2023

snoopy-log-all-commands-on-linux-server-tux-logo

To keep a good eye on installed Debian Linux server security if you have to be PCI compliant (e.g. follow a high security) standards or you work in a company, where system security is crucial and any kind of security breach is untorrelated and in case of unexpected security holes exploited on running system processess listening on network peripherals (that malicious crackers) does to be able to easily identify what really happened e.g. do a Security RCA (Root Cause Analysis) for how this hack happened in order to mitigate it for future if possible capture the crackers and close the security hole the better, some kind of paranoid running program logging is required.

For such higher security systems, Linux / BSD / UNIX sysadmins can benefit from;

Snoopy command logger – a small library that logs all program executions on your Linux/BSD system.

Embedding snoopy into a running uptodate system is relatively easy, you either have to download the respective distribution package (in this particular article that would be Debian GNU / Linux) or for Linux distributions, that doesn't have the package integrated into the existing package repositories or externally available package repos, the code can be easily git cloned and installed from github snoopy program page following the README.md


However consider that snoopy run and logging the executed commands, make sure that if you use it you have rsyslogd configured to log to external logging server to make sure (someone did not manipulate the running system to avoid their actions being logged by snoopy, this is pointed by snoopy security disclaimer on the FAQ of official github snoopy project page, the page reads as so:

Security disclaimer
WARNING: Snoopy is not a reliable auditing solution.
Rogue users can easily manipulate environment to avoid their actions being logged by Snoopy. Consult this FAQ entry for more information.                


Most likely this warning is pointed out by the tool authors, in order to set the logging Tool creators free for any liability in case if someone uses the snoopy tool for some unauthorized logging
and sniffing of systems etc.

Before we proceed with the tool, install first for some clarity it is a good idea to know on what kind of Debian Linux you're about to install Snoopy command logger.

root@linux:~ # cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 11 (bullseye)"
NAME="Debian GNU/Linux"
VERSION_ID="11"
VERSION="11 (bullseye)"
VERSION_CODENAME=bullseye
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"


1. Prepare separate log file for snoopy that will keep log of every system command run by running processes visible by (ps -ef)

Next check the permissions user / group and read / write / executable flags with which the default generated rsyslog will be writting and set snoopy to whatever you would like it to write with

root@linux:~ # cat /etc/rsyslog.conf | grep "^\$File\|\$Umask"~
$FileOwner root
$FileGroup adm
$FileCreateMode 0640


Create Rsyslog configuration for snoopy.log

root@linux:~ # cat << EOF | sudo tee /etc/rsyslog.d/01-snoopy.conf
# Send snoopy messages to a dedicated logfile
if (\$programname startswith "snoopy") then {
  action(type="omfile" fileOwner="root" fileGroup="root" fileCreateMode="0600" file="/var/log/snoopy.log")
  stop
}
EOF


To make sure that snoopy library will be preloaded after installation on next boot:

root@linux:~ # cat << EOF | sudo debconf-set-selections
snoopy snoopy/install-ld-preload boolean true
EOF

 

root@linux:~ # systemctl restart rsyslog

 

root@linux:~ # systemctl status rsyslog
● rsyslog.service – System Logging Service
     Loaded: loaded (/lib/systemd/system/rsyslog.service; enabled; vendor preset: enabled)
     Active: active (running) since Tue 2023-03-14 12:59:05 EET; 59min ago
TriggeredBy: ● syslog.socket
       Docs: man:rsyslogd(8)
             man:rsyslog.conf(5)
             https://www.rsyslog.com/doc/
   Main PID: 713745 (rsyslogd)
      Tasks: 6 (limit: 4654)
     Memory: 1.1M
        CPU: 548ms
     CGroup: /system.slice/rsyslog.service
             └─713745 /usr/sbin/rsyslogd -n -iNONE

мар 14 12:59:05 haproxy2 systemd[1]: Started System Logging Service.
мар 14 12:59:05 haproxy2 rsyslogd[713745]: warning: ~ action is deprecated, consider using the 'stop' statement instead [v8.210>
мар 14 12:59:05 haproxy2 rsyslogd[713745]: [198B blob data]
мар 14 12:59:05 haproxy2 rsyslogd[713745]: [198B blob data]
мар 14 12:59:05 haproxy2 rsyslogd[713745]: [198B blob data]
мар 14 12:59:05 haproxy2 rsyslogd[713745]: [198B blob data]
мар 14 12:59:05 haproxy2 rsyslogd[713745]: imuxsock: Acquired UNIX socket '/run/systemd/journal/syslog' (fd 3) from systemd.  [>
мар 14 12:59:05 haproxy2 rsyslogd[713745]: [origin software="rsyslogd" swVersion="8.2102.0" x-pid="713745" x-info="https://www.>
мар 14 13:19:05 haproxy2 rsyslogd[713745]: — MARK —
мар 14 13:39:05 haproxy2 rsyslogd[713745]: — MARK —


2. Install snoopy deb package and configure it

root@linux:~ # apt install snoopy
Четене на списъците с пакети… Готово
Изграждане на дървото със зависимости… Готово
Четене на информацията за състоянието… Готово
Следните пакети са били инсталирани автоматично и вече не са необходими:
  bsdmainutils cpp-8 geoip-database libasan5 libbind9-161 libcroco3 libdns1104 libdns1110 libevent-core-2.1-6
  libevent-pthreads-2.1-6 libgdk-pixbuf-xlib-2.0-0 libgdk-pixbuf2.0-0 libgeoip1 libicu63 libisc1100 libisc1105 libisccc161
  libisccfg163 libisl19 liblwres161 libmpdec2 libmpx2 libperl5.28 libpython2-stdlib libpython2.7-minimal libpython2.7-stdlib
  libpython3.7-minimal libpython3.7-stdlib libreadline7 netcat-traditional node-ansi-align node-arrify node-bluebird
  node-boxen node-builtin-modules node-call-limit node-camelcase node-cli-boxes node-cliui node-co node-concat-stream
  node-config-chain node-cross-spawn node-cyclist node-decamelize node-decompress-response node-deep-extend node-detect-indent
  node-detect-newline node-duplexer3 node-duplexify node-editor node-end-of-stream node-errno node-execa node-find-up
  node-flush-write-stream node-from2 node-fs-vacuum node-get-caller-file node-get-stream node-got node-has-symbol-support-x
  node-has-to-string-tag-x node-import-lazy node-invert-kv node-is-buffer node-is-builtin-module node-is-npm node-is-object
  node-is-plain-obj node-is-retry-allowed node-is-stream node-isurl node-json-buffer node-kind-of node-latest-version
  node-lazy-property node-lcid node-libnpx node-locate-path node-lowercase-keys node-mem node-merge-stream node-mimic-fn
  node-mimic-response node-minimist node-mississippi node-node-uuid node-npm-run-path node-os-locale node-p-cancelable
  node-p-finally node-p-limit node-p-locate node-p-timeout node-package-json node-parallel-transform node-path-exists
  node-path-is-inside node-prepend-http node-proto-list node-prr node-pump node-pumpify node-qw node-rc
  node-registry-auth-token node-registry-url node-require-directory node-require-main-filename node-semver-diff node-sha
  node-shebang-command node-shebang-regex node-slide node-sorted-object node-stream-each node-stream-iterate node-stream-shift
  node-strip-eof node-strip-json-comments node-term-size node-through2 node-timed-out node-typedarray node-uid-number
  node-unpipe node-url-parse-lax node-url-to-options node-which-module node-widest-line node-wrap-ansi node-xdg-basedir
  node-xtend node-y18n node-yargs node-yargs-parser perl-modules-5.28 python-pkg-resources python2 python2-minimal python2.7
  python2.7-minimal python3.7-minimal
Използвайте „apt autoremove“ за да ги премахнете.
Следните НОВИ пакети ще бъдат инсталирани:
  snoopy
0 актуализирани, 1 нови инсталирани, 0 за премахване и 1 без промяна.
Необходимо е да се изтеглят 46,0 kB архиви.
След тази операция ще бъде използвано 124 kB допълнително дисково пространство.
Изт:1 http://deb.debian.org/debian bullseye/main amd64 snoopy amd64 2.4.12-1 [46,0 kB]
Изтеглени 46,0 kB за 0с (93,2 kB/сек)
Предварително настройване на пакети …


Selecting previously unselected package snoopy.
(Reading database … 56067 files and directories currently installed.)
Preparing to unpack …/snoopy_2.4.12-1_amd64.deb ...
Unpacking snoopy (2.4.12-1) …
Setting up snoopy (2.4.12-1) …
Processing triggers for libc-bin (2.31-13+deb11u5) …

root@linux:/etc# ls -al /var/log/snoopy.log
-rw——- 1 root root 14472 14 мар 13:40 /var/log/snoopy.log

Any specific configuration for snoopy can be tuned through /etc/snoopy.ini

Now you will find all the commands executed by all monitored running processes in /var/log/snoopy.

root@linux:/etc# tail -30 /var/log/snoopy.log
Mar 14 12:59:32 haproxy2 snoopy[713804]: [login:root ssh:(192.168.0.1 62796 192.168.0.210 22) sid:713792 tty:/dev/pts/2 (0/root) uid:root(0)/root(0) cwd:/]: ldconfig
Mar 14 12:59:32 haproxy2 snoopy[713806]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: who
Mar 14 12:59:32 haproxy2 snoopy[713807]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: wc -l
Mar 14 13:00:07 haproxy2 snoopy[713815]: [login:root ssh:((undefined)) sid:713815 tty:(none) ((none)/(none)) uid:root(0)/root(0) cwd:/usr/lib/sysstat]: /usr/lib/sysstat/sadc -F -L -S DISK 1 1 /var/log/sysstat
Mar 14 13:00:32 haproxy2 snoopy[713823]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: who
Mar 14 13:00:32 haproxy2 snoopy[713824]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: wc -l
Mar 14 13:01:32 haproxy2 snoopy[713834]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: who
Mar 14 13:01:32 haproxy2 snoopy[713835]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: wc -l
Mar 14 13:02:32 haproxy2 snoopy[713843]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: who
Mar 14 13:02:32 haproxy2 snoopy[713844]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: wc -l
Mar 14 13:03:32 haproxy2 snoopy[713855]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: who
Mar 14 13:03:32 haproxy2 snoopy[713856]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: wc -l
Mar 14 13:04:32 haproxy2 snoopy[713868]: [login:zabbix ssh:((undefined)) sid:682168 tty:(none) ((none)/(none)) uid:zabbix(108)/zabbix(108) cwd:/]: who


3. Set up logrotation (archiving) for snoopy logs

root@linux:/etc# vim /etc/logrotate.d/snoopy    


/var/log/snoopy.log {
        daily
        rotate 30
        compress
        delaycompress
        notifempty
        create 640 root adm

}
 

If you want to test logrotation without actually rotating the file:               

root@linux:/etc# logrotate –debug –force /etc/logrotate.d/snoopy   
  log needs rotating
rotating log /var/log/snoopy.log, log->rotateCount is 30
dateext suffix '-20230314'
glob pattern '-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'
previous log /var/log/snoopy.log.1 does not exist
renaming /var/log/snoopy.log.30.gz to /var/log/snoopy.log.31.gz (rotatecount 30, logstart 1, i 30),
…
renaming /var/log/snoopy.log.1.gz to /var/log/snoopy.log.2.gz (rotatecount 30, logstart 1, i 1),
renaming /var/log/snoopy.log.0.gz to /var/log/snoopy.log.1.gz (rotatecount 30, logstart 1, i 0),
log /var/log/snoopy.log.31.gz doesn't exist — won't try to dispose of it
renaming /var/log/snoopy.log to /var/log/snoopy.log.1
creating new /var/log/snoopy.log mode = 0640 uid = 0 gid = 4


4. Monitoring only selected applications  executed commands with snoopy                                                                             

By default snoopy after installed will set itself to monitor all kind of running processes on the system is done by preloading the ldconfig's (libc) ld.so.preload

root@haproxy2:/etc# cat /etc/ld.so.preload
/lib/x86_64-linux-gnu/libsnoopy.so

If you want to monitor a concrete application and not log everything from the running processes in process list, comment this out this line run ldconfig command

Then to any concrete application you would like to monitor with snoopy add to its init script either /etc/init.d/app_init_script or to systemctl's start script before the application binary program run:

export LD_PRELOAD=/lib/snoopy.so


  As per the README states


 Snoopy is placed in /etc/ld.so.preload to trap all occurrences of exec, if 
 you wish to monitor only certain applications you can do so through the    
 LD_PRELOAD environment variable.
Simply set it to /lib/snoopy.so before  loading the application.

For example

 # export LD_PRELOAD=/lib/snoopy.so                                           
 # lynx http://example.com/                           

 

Tags: , , , , , , , , , , , , , , ,
Posted in Linux, Security, System Administration, System Optimization | 1 Comment »

« Older Entries