Zabbix Server: ZBX Icon not getting "green", although agents are properly connected

[sscheib]

Hello community,

I am very new to Zabbix, so this might be a common issue, which I am just not aware of how to fix.
Within my Zabbix instance I have a couple of Linux servers and as well as some routers (openwrt) connected via the Zabbix agent. For some reason, some of them are not showing the green "ZBX" icon in the column connectivity.
The clients in question are identically configured as the clients, which show up as properly connected. The clients in question are:
rsyslog.lan
general information

root@rsyslog:/var/log/remote# uname -a
Linux rsyslog.lan 4.19.75-v7+ #1270 SMP Tue Sep 24 18:45:11 BST 2019 armv7l GNU/Linux
root@rsyslog:/var/log/remote# cat /etc/debian_version 
10.2
root@rsyslog:/var/log/remote# cat /proc/device-tree/model  
Raspberry Pi 3 Model B Rev 1.2
root@rsyslog:/var/log/remote# dpkg -l | grep zabbix
ii  zabbix-agent                         1:4.0.16-1+buster                   armhf        Zabbix network monitoring solution - agent
ii  zabbix-get                           1:4.0.16-1+buster                   armhf        Zabbix network monitoring solution - get
ii  zabbix-release                       1:4.0-3+buster                      all          Zabbix official repository configuration
ii  zabbix-sender                        1:4.0.16-1+buster                   armhf        Zabbix network monitoring solution - sender
root@rsyslog:/var/log/remote#

configuration zabbix agent

root@rsyslog:/var/log/remote# grep -vE '#|^$' /etc/zabbix/zabbix_agentd.conf 
PidFile=/var/run/zabbix/zabbix_agentd.pid
LogFile=/var/log/zabbix/zabbix_agentd.log
LogFileSize=0
Server=10.10.20.8
ServerActive=10.10.20.8
Hostname=rsyslog.lan
Include=/etc/zabbix/zabbix_agentd.d/*.conf
root@rsyslog:/var/log/remote#

access-point.lan
general information
root@OpenWrt:~# uname -a
Linux OpenWrt 4.14.120 #0 SMP Wed May 22 19:27:44 2019 armv7l GNU/Linux
root@OpenWrt:~# opkg list-installed | grep zabbix
zabbix-agentd - 4.0.11-2

configuration zabbix agent
root@OpenWrt:~# grep -vE '#|^$' /etc/zabbix_agentd.conf
LogType=system
SourceIP=10.10.20.9
Server=10.10.20.8
ListenIP=10.10.20.9
StartAgents=1
ServerActive=10.10.20.8
Hostname=access-point.lan
Include=/etc/zabbix_agentd.conf.d/
root@OpenWrt:~#

Besides the log directive they are configured the same - I guess.
Comparing it with two working devices, which show up as "ZBX"-enabled:
openwrt.home

[email protected]:~/scripts/monitoring$ grep -vE '#|^$' /etc/zabbix_agentd.conf  
LogType=system
DebugLevel=3
SourceIP=10.1.1.4
Server=10.10.20.8
ListenIP=10.1.1.4
StartAgents=1
ServerActive=10.10.20.8
Hostname=openwrt.home
Include=/etc/zabbix_agentd.conf.d/
[email protected]:~/scripts/monitoring$

emby.lan

root@emby:/home/steffen# grep -vE '#|^$' /etc/zabbix/zabbix_agentd.conf 
PidFile=/var/run/zabbix/zabbix_agentd.pid
LogFile=/var/log/zabbix-agent/zabbix_agentd.log
LogFileSize=0
DebugLevel=5
Server=10.10.20.8
ServerActive=10.10.20.8
Hostname=emby.lan
AllowRoot=1
Include=/etc/zabbix/zabbix_agentd.conf.d/*.conf
root@emby:/home/steffen#

Futhermore I am able to query the clients in question (access-point.lan, rsyslog.lan) from the zabbix server with a zabbix-get:

root@zabbix:/home/steffen# zabbix_get -s rsyslog.lan -k agent.version
4.0.16
root@zabbix:/home/steffen# zabbix_get -s access-point.lan -k agent.version           
4.0.11
root@zabbix:/home/steffen#

Also new data are retrieved/send from the clients in question constantly - so they are connected .. but for some reasons, don't show up as connected.

Neither in the zabbix agent log, nor in the zabbix server log can I find any hint on why they are not showing up as "connected".
Following some information about the zabbix server:

root@zabbix:/home/steffen# dpkg -l | grep zab
ii  zabbix-agent                    1:4.4.4-1+buster                    armhf        Zabbix network monitoring solution - agent
ii  zabbix-frontend-php             1:4.4.4-1+buster                    all          Zabbix network monitoring solution - PHP front-end
ii  zabbix-get                      1:4.4.4-1+buster                    armhf        Zabbix network monitoring solution - get
ii  zabbix-release                  1:4.4-1+buster                      all          Zabbix official repository configuration
ii  zabbix-server-mysql             1:4.4.4-1+buster                    armhf        Zabbix network monitoring solution - server (MySQL)
root@zabbix:/home/steffen#

Can somebody help me out here?

Thanks!

[1berto]

Are you using active or passive items?
Maybe i'm wrong, but i think that the item turns green only with passive checks (Zabbix agent type, not Zabbix agent active).
If i'm correct you can create one passive check (like agent.ping) just to have the ZBX indicator and others as active checks.

[sscheib]

I am using active checks. What's confusing is, that on all hosts it seems to work properly, but not on those two - they all share the very same templates:
- Template Module ICMP Ping
- Template OS Linux by Zabbix agent active

//EDIT
agent.ping is already on those hosts (active check however)

[Atsushi]

If there is only an active check, the state of the ZBX icon does not change. If there is a green icon when there is only an active check at present, I think that it only remains that the value obtained by the passive check was successful once.

https://www.zabbix.com/documentation/4.0/manual/web_interface/frontend_sections/configuration/hosts#unknown_host_status

https://www.zabbix.com/documentation/4.4/manual/web_interface/frontend_sections/configuration/hosts#unknown_host_status

[sscheib]

I stand corrected.
On the other hosts I had Template OS Linux by Zabbix agent (without active) applied - I changed the templates now to Template OS Linux by Zabbix agent active, but added Template Module Zabbix agent instead of Template Module Zabbix agent active.
As of now, it seems to be working perfectly fine - thanks for your help guys!

Have a nice christmas!

[nagaraj]

I'm having the same problem with zabbix agent 6.0 active check on Ubuntu server 20.04, yet it works good on Ubuntu 22.04. Passive check works fine on both versions.

Guys, Has anyone discovered a solution to this problem?

SSH login is only supported with an active check, and we use a few Ubuntu 20.04 servers.