ufw question

[wiskey]

Zabbix server shows 'interrupted system call' when the agentd ufw active. And the keys use Zabbix agent (active) are okay, but such as 'agent.ping' using Zabbix agent got the data failed.
If I disable the ufw, all is okay.
What's the different?

[Atsushi]

By using connection restrictions in ufw, you can separate the rules for accessing the server from other networks (incoming) and the rules for accessing other networks from the server (outgoing).
Probably, since there are no particular restrictions on outgoing, Zabbix agent side can access Zabbix server side, so I think that item type "Zabbix agent (active)" can be monitored. On the other hand, for items whose item type is "Zabbix agent", access is denied by ufw when trying to connect to the Zabbix agent from the Zabbix server side. If you want to use items of type "Zabbix Agent", you need to add ufw settings to allow connections from the Zabbix server side using port number 10050.
To see what your current settings are, run the following command:

$ sudo ufw status​