Managing Agents

Managing Agents#

In this section we present some procedure to fix issues related to Carbonio Mesh agents.

No UDP Connections#

There are situations in which a service-discover agent fails to connect to the service-discover server or to other agents using UDP, but is successful via TCP. When this happens, in the syslog log file, warning messages like the following one are recorded:

Mar  9 20:08:29 proxy01 service-discoverd[3189618]: 2025-03-09T20:08:29.578+0100 [WARN]  agent.client.memberlist.lan: memberlist: Was able to connect to srv1.example.com over TCP but UDP probes failed, network may be misconfigured

Mar  9 20:08:30 proxy01 service-discoverd[3189618]: 2025-03-09T20:08:30.579+0100 [WARN]  agent.client.memberlist.lan: memberlist: Was able to connect to agent-mbox01.example.com over TCP but UDP probes failed, network may be misconfigured

Mar  9 20:08:31 proxy01 service-discoverd[3189618]: 2025-03-09T20:08:31.580+0100 [WARN]  agent.client.memberlist.lan: memberlist: Was able to connect to agent-files01.example.com over TCP but UDP probes failed, network may be misconfigured

These messages show that proxy01 (the agent that establishes the communication) can not communicate with agents of srv1, agent-mbox01, agent-files01 and are marked as [WARN]], i.e., warnings, the agents can still communicate via TCP and the service-discover is working–as shown also in the Carbonio Mesh Administration Interface, this is a symptom of a communication problem within the network.

Possible reasons for the problem are:

  • A blocked (destination) UDP Port 8301 between the source agent, i.e the agent starting the communication, and the destination agents or server.

  • An unwanted SNAT rule of the agent’s source IP address: if the UDP connection is masqueraded with an IP address that is unknown to Carbonio Mesh destination agent or server, then the connection fails

In both cases, to fix the problem it is necessary to investigate the firewall rules to find a misconfiguration or some offending rule.

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