Debian 12 Zabbix agent 2 not connecting to server

[Greg_E]

This is probably something really dumb and basic, but hoping to get some help. I'm just starting out with Zabbix 7, I have 1 windows server connected and monitoring, and just installed the Agent 2 on a Debian 12 (updated today). Systemctl shows the status of the agent as enabled and running (after a reboot to make certain). Netstat does not show anything using that port (or I'm running the wrong commands). I didn't install a firewall on this server (at least not yet) so the port shouldn't be blocked, but I might not be checking correctly. The agent was installed with sudo as opposed to setting su as root, not sure if this matters.

This is the error I get when I click on the red ZBX

Get value from agent failed: cannot read response: cannot read from socket: [104] Connection reset by peer

The time on all these servers is within a minute, probably closer to seconds because they are all synced to a GPS NTP server.

This server is running Fogserver to image my clients, I don't think it grabs port 10050 or 10051, so this should be OK.

What do I need to check to figure this out?

And again, sorry for what is probably a really basic question, I'm not that strong with Linux, so kind of struggling the whole way.

[Greg_E]

Following up... I removed Agent2 and all associated plugins, reboot, install Agent and set systemctl to enable and start, reboot. Check and Agent is still running and waiting for connection.

Back to the server and I'm getting a different error:

Received empty response from Zabbix Agent at [172.17.x.x]. Assuming that agent dropped connection because of access permissions.

I'm using unencrypted connections right now, because easier.

Fogserver uses the following ports, but it looks like I should be OK here:

MySQL - 3306
FTP – tcp 20,21
SSH – tcp 22
TFTP – udp 69
HTTP(s) – tcp 80,443
Portmap – tcp/udp 111
NFS – tcp/udp 2049
Transfer ports – tcp/udp 1024 – 65535

The transfer ports in the last line are the only ones that overlap, but they should only open when a transfer is being done. I know I'm missing something basic here, just not sure where to look.

Installed nmap and checked 127.0.0.1 and port 10050, it says open and associated to Zabbix-Agent, so the port is OK. There must be a permission or a config file issue on this linux computer.

[Greg_E]

Found it, needed to edit the config file and enter the server IP address.