ZBX_NOTSUPPORTED on net.udp.listen[xx]

[Julien Vasseur]

Dear all,

I have a Zabbix server 3.4 and an agent on Ubuntu 14.04.2.

On the web server, my item "net.udp.listen" is "Not supported by Zabbix agent" altough it should be (cfr. the matrix on the documentation).

Anyone could help?

When i perform a local check, i get a correct response:

# /usr/sbin/zabbix_agentd -t 'net.udp.listen[401]'
net.udp.listen[401]                           [u|1]]

And here is the log on the server:
20412:20171122:195036.055 In get_values()
20412:20171122:195036.055 In DCconfig_get_poller_items() poller_type:0
20412:20171122:195036.055 End of DCconfig_get_poller_items():1
20412:20171122:195036.055 In substitute_key_macros() data:'net.udp.listen[401]'
20412:20171122:195036.055 End of substitute_key_macros():SUCCEED data:'net.udp.listen[401]'
20412:20171122:195036.055 In substitute_simple_macros() data:'10050'
20412:20171122:195036.055 In get_value() key:'net.udp.listen[401]'
20412:20171122:195036.055 In get_value_agent() host:'myhost' addr:'myhost_ip' key:'net.udp.listen[401]' conn:'unencrypted'
20412:20171122:195036.062 Sending [net.udp.listen[401]
]
20415:20171122:195036.068 __zbx_zbx_setproctitle() title:'poller #4 [got 0 values in 0.000177 sec, getting values]'
20415:20171122:195036.068 In get_values()
20415:20171122:195036.068 In DCconfig_get_poller_items() poller_type:0
20415:20171122:195036.068 End of DCconfig_get_poller_items():0
20415:20171122:195036.068 In DCconfig_get_poller_nextcheck() poller_type:0
20415:20171122:195036.068 End of DCconfig_get_poller_nextcheck():1511380250
20415:20171122:195036.068 End of get_values():0
20415:20171122:195036.068 __zbx_zbx_setproctitle() title:'poller #4 [got 0 values in 0.000199 sec, idle 5 sec]'
20412:20171122:195036.070 get value from agent result: 'ZBX_NOTSUPPORTED'
20412:20171122:195036.070 End of get_value_agent():NOTSUPPORTED
20412:20171122:195036.070 Item [myhost:net.udp.listen[401]] error: Not supported by Zabbix Agent
20412:20171122:195036.070 End of get_value():NOTSUPPORTED

[kaspars.mednis]

Hello,

can you post a screenshot of your item config ?
it will help to find the problem faster

Regards,
Kaspars

[Julien Vasseur]

Here it is...

Nothing fancy, isn't it?

[kaspars.mednis]

Sorry, i can not see the screenshot

Just tried to make an item net.udp.listen[401] on Ubuntu 14.04, worked as expected...

[Julien Vasseur]

sorry... here it is.


Yes, I know... this works well on other servers.
I d'ont have any clue about what goes wrong here?

[kaspars.mednis]

Maybe something interesting in zabbix_agentd log on remote host ?

[Julien Vasseur]

nope...

here is the agent trace with loglevel=5

  2148:20171123:154113.972 __zbx_zbx_setproctitle() title:'listener #2 [waiting for connection]'
  2148:20171123:154113.976 __zbx_zbx_setproctitle() title:'listener #2 [processing request]'
  2148:20171123:154113.976 Requested [net.udp.listen[401]]
  2148:20171123:154113.976 Sending back [ZBX_NOTSUPPORTED]

[dimir]

Could it be a SELinux issue on the agent host?

[Julien Vasseur]

No it's an ordinary Ubuntu Xenial (16.04 LTS) (GNU/Linux 4.4.38-std-1 x86_64 )

[kloczek]

No it's an ordinary Ubuntu Xenial (16.04 LTS) (GNU/Linux 4.4.38-std-1 x86_64 )

Doesn't matter is it ordiunary Ubuntu or not.
You been checking key zabbix_agentd -t <key>" from root which has permissions for everything then zabbix_agentd process is running from zabbix user which doses not have by default to many things if you have enabled SELinux.

You have two options: disable SELinux or add proper SELinux policies.

[Julien Vasseur]

I meant SELinux is not installed on my system.

Could it be another user restriction?

[kaspars.mednis]

You can try to reproduce it from zabbix user (may need to temporay adjust the /etc/passwd entry from

zabbix:x:111:117::/var/lib/zabbix/:/bin/false

to

zabbix:x:111:117::/var/lib/zabbix/:/bin/bash

for test purposes

from root:

su - zabbix
/usr/sbin/zabbix_agentd -t 'net.udp.listen[401]'

What happens here ?

[Julien Vasseur]

Yeah... there's the pickel ... in that case, the agent respond indeed "ZBX_NOTSUPPORTED"

$ /usr/sbin/zabbix_agentd -t 'net.udp.listen[401]'
net.udp.listen[401]                           [m|ZBX_NOTSUPPORTED]

I have other zabbix items that work prefectly fine... I don't see how to fix this.

[Julien Vasseur]

After some reseach it seems to be related with grsecurity that has been installed by default by my VPS provider (ovh.com)...

The user zabbix cannot access /proc/net/*

I check with its configuration and i post the solution...