Posts Tagged ‘psk’

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 ! 🙂

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.

How to connect to WiFi network using console or terminal on GNU / Linux

Wednesday, November 2nd, 2011

iwlist-screenshot-howto-connect-to-wifi-in-text-console-linux-wpasupplicant

Sometimes its useful to connect to Wireless Networks using console . The reasons for that might be many, one possible reason is to be able to debug, Wireless connection failures or simply omit the use of the many available GUI wifi connection programs.

As a first step before connecting in terminal is to look up for the wifi networks available for connection, this is done with cmd:

linux:~# iwlist wlan0 scanning
wlan0 Scan completed :
Cell 01 - Address: 00:24:01:90:8F:38
Channel:7
Frequency:2.442 GHz (Channel 7)
Quality=70/70 Signal level=-39 dBm
Encryption key:on
ESSID:"magdanoz"
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s
Bit Rates:6 Mb/s; 9 Mb/s; 12 Mb/s; 48 Mb/s; 18 Mb/s
24 Mb/s; 36 Mb/s; 54 Mb/s
Mode:Master
Extra:tsf=000000034f5c786b
Extra: Last beacon: 68ms ago
IE: Unknown: 00086D616764616E6F7A
IE: Unknown: 010482848B96
IE: Unknown: 030107
IE: Unknown: 32080C1218602430486C
IE: Unknown: CC0700CC020000018A
IE: Unknown: CC0700CC0300000100
IE: WPA Version 1
Group Cipher : TKIP
Pairwise Ciphers (2) : TKIP CCMP
Authentication Suites (1) : PSK
IE: IEEE 802.11i/WPA2 Version 1
Group Cipher : TKIP
Pairwise Ciphers (2) : TKIP CCMP
Authentication Suites (1) : PSK
Cell 02 - Address: 00:1E:2A:60:5E:DC
Channel:1
...

To just list the ESSID s of the wifi networks:

linux:~# iwlist wlan0 scanning|grep -i 'essid'
ESSID:"magdanoz"
ESSID:"default"
ESSID:"todorov"
ESSID:"BTC-ADSL"
ESSID:"Zahari"
ESSID:"Drago"

1. Connecting to Open Wireless Network

Now from the above output it is clear 6 wifi networks are available for connection. The default wifi network from the list is an Open network (e.g. without pass). To connect to it I use cmd:

linux:~# /sbin/iwconfig wlan0 essid 'default'
linux:~# /sbin/iwconfig wlan0 key open

After connected to configure IP, Gateway and DNS from a DHCP server running on the WIFI router, dhclient cmd is used:

linux:~# /sbin/dhclient wlan0

2. Connecting to WEP 64bit / 128bit encrypted network

linux:~# /sbin/iwconfig wlan0 key 1234-5678-9101-1213

3. Connecting to WPA / WPA2 encrypted wifi network

To connect to WPA or WPA2 encrypted network its necessery to have installed wpasupplicant package. The name of the package might vary in different distributions on Debian and Ubuntu, the name of the package is wpasupplicant, on Fedora, CentOS and RHEL the package that has to be in is wpa_supplicant :
After having installed the wpa_supplicant to connect to the network with ESSID name magdanoz , wpa_passphrase is used first:

linux:~# /usr/bin/wpa_passphrase magdanoz Secret_Wifi_Password | tee -a /etc/wpa_supplicant.conf
network={
ssid="magdanoz"
#psk="Secret_Wifi_Password"
psk=6f7590250c4496ff7bf8dd25199ac3bb5a614d4bc069975aa884bcf084da73bc
}

As you see in above command the secret password key is generated printed on the screen and then added to /etc/wpa_supplicant.conf , necessery to establish the wireless connection with wpa_supplicant with cmd:

linux:~# /sbin/wpa_supplicant wpa_supplicant -d wext -i wlan0 -c /etc/wpa_supplicant.conf -B

-d wext instructs wpa_supplicant to use (Linux wireless extension driver).
-B tells wpa_supplicant to background the connection to prevent the wireless connection to drop off, if the console / terminal from which it is launched gets closed.

In case of succesful connection with wpa_supplicant , once again IP, Gateway and DNS is configured fetching the settings from the wifi hotspot dhcp server:

linux:~# /sbin/dhclient wlan0

General information about the wireless network and info related to the established connection can be obtained with /usr/bin/iwconfig :

linux:~# /sbin/iwconfig
lo no wireless extensions.
eth0 no wireless extensions.
wlan0 IEEE 802.11abg ESSID:"magdanoz"
Mode:Managed Frequency:2.442 GHz Access Point: 00:24:00:90:8F:38
Bit Rate=54 Mb/s Tx-Power=15 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link Quality=70/70 Signal level=-39 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

To configure the exact channel over which the wireless connection will be established again is done with iwconfig, for instance to configure wlan0 wifi connection established to be on wifi channel 7:

linux:~# /sbin/iwconfig wlan0 channel 11

By default iwconfig is set to automatically set the channel based on connected network ESSID , if the channel is modified to some specific number to revert it back use:

linux:~# /sbin/iwconfig wlan0 channel auto