Timeout while connecting to SNMP agent

[kitikant]

I use Zabbix 7.0.4 on CentOS9. I try to monitor IP office and Contact center with ZBX via SNMPv1, v2. I've configured the same community string on both side (my devices and ZBX) but it cannot be connected and return

Timeout while connecting to <device's IP>

I have collected that my IPO and CC have sent some trap noti to ZBX server by using

tcpdump

but why it still cannot connect with ZBX? cuz the firewall and security already allow port 161,162 and community string is correct.


here is my config on zabbix interface:

[cyber]

There cannot be 2 source IP-s. How would it choose, which one to use..?

SourceIP
Source IP address for:
- outgoing connections to Zabbix proxy and Zabbix agent;
- agentless connections (VMware, SSH, JMX, SNMP, Telnet and simple checks);
- HTTP agent connections;
- script item JavaScript HTTP requests;
- preprocessing JavaScript HTTP requests;
- sending notification emails (connections to SMTP server);
- webhook notifications (JavaScript HTTP connections);
- connections to the Vault

So everythink initiated by Server will use that IP. Server will still listen on all existing ones, if you do not specify ListenIP. So if some of your devices are able to communicate with one IP and others with other, you need to do some networking magic there, what I have no idea about...

[ISiroshtan]

What you showing is problem with SNMP polling. Sending SNMP traps would have nothing to do with it.
You can start with verifying the communication flow is properly working by running snmpget or snmpwalk commands from Zabbix server CMD asking for same OID with same community name. If it works - next would be looking into Zabbix. If it does not - back to network, firewall or end device settings.

[kitikant]

What you showing is problem with SNMP polling. Sending SNMP traps would have nothing to do with it.
You can start with verifying the communication flow is properly working by running snmpget or snmpwalk commands from Zabbix server CMD asking for same OID with same community name. If it works - next would be looking into Zabbix. If it does not - back to network, firewall or end device settings.

it doesn't work when i use SNMPwalk from ZBX server, return

timeout: No response from agent

. firewall is already open for port 161/udp and i can ping the agent device that mean the network shouldn't have any trouble, right? the community string its already correct at both end. Does it mean i should check the SNMP agent configuration again? even if it is correct.

[cyber]

ping and snmp/161 port are not really connected... but if yu say that fw IS open but you still get timeout connecting, then there is something wrong here...either that FW is not actually open or there is something on device side preventing access. ACL? local FW? (still) wrong community ? Even if you configured community and credentials, are those related processes running on those (avaya, I assume) hosts?

[kitikant]

ping and snmp/161 port are not really connected... but if yu say that fw IS open but you still get timeout connecting, then there is something wrong here...either that FW is not actually open or there is something on device side preventing access. ACL? local FW? (still) wrong community ? Even if you configured community and credentials, are those related processes running on those (avaya, I assume) hosts?

I've found out that the interface that use for communication with agent is still private interface not public interface (I have two interfaces on ZBX server). This ZBX server will be used to monitor local agent devices and external agent devices, so i have both. After i figure it out, I change the config in zabbix_server.conf by adding SourceIP= my-zabbix-public-ip then restart zabbix-server, but it appears that the status of all host devices which be monitored on zabbix interface including those work before and those that i have trouble in this forum become failing. do I need to add

SourceIP=local ip, public ip

in config file?

[cyber]

There cannot be 2 source IP-s. How would it choose, which one to use..?

SourceIP
Source IP address for:
- outgoing connections to Zabbix proxy and Zabbix agent;
- agentless connections (VMware, SSH, JMX, SNMP, Telnet and simple checks);
- HTTP agent connections;
- script item JavaScript HTTP requests;
- preprocessing JavaScript HTTP requests;
- sending notification emails (connections to SMTP server);
- webhook notifications (JavaScript HTTP connections);
- connections to the Vault

So everythink initiated by Server will use that IP. Server will still listen on all existing ones, if you do not specify ListenIP. So if some of your devices are able to communicate with one IP and others with other, you need to do some networking magic there, what I have no idea about...

[kitikant]

get it.
Thank you for your assistance that help me figure out the way to deal with this problem.