- SELinux
https://www.zabbix.com/forum/showthread.php?t=47375&highlight=selinux
You have disabled it - OK
- Firewall
Try to turn off firewall also
- PHP frontend/zabbix server config
Common problem is when zabbix_server is listening only on IP, not on localhost (netstat -tanp | grep :10051), but frontend is configured for localhost:10051, test and configure frontend/zabbix server properly
# grep ZBX_SERVER /etc/zabbix/web/zabbix.conf.php
$ZBX_SERVER = 'localhost';
$ZBX_SERVER_PORT = '10051';
# telnet localhost 10051
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
If server is listening on all interfaces (localhost included), then I can use also localhost in the frontend config:
# netstat -tanp | grep :10051 | grep LISTEN
tcp 0 0 0.0.0.0:10051 0.0.0.0:* LISTEN 825/zabbix_server
tcp6 0 0 :::10051 :::* LISTEN 825/zabbix_server