Port usage

The RMC daemon uses TCP port 657 to accept requests from RMC client applications, such as CSM and the various RMC commands that are running remotely from the node upon which the RMC daemon is running.

The RMC commands are documented in the Technical Reference: RSCT for AIX® and Technical Reference: RSCT for Multiplatforms guides. The RMC daemon binds to this port only when enabled to accept remote client connections. The daemon is automatically enabled to accept remote connections when CSM is installed on the node, when xCAT optionally configures the node for RMC monitoring, when the node is a member of a peer domain, or when the node is an operating system image in the IBM® Power Systems processor-based servers. The rmcctrl command enables the daemon to accept remote client connections or disables the daemon from accepting remote client connections. Note that disabling this function can result in failure of applications expecting to remotely connect to an RMC daemon.

The maximum number of remote connections outstanding to an RMC daemon at any time can be no more than 232.

The RMC daemon also uses the UDP port 657 to communicate with all other RMC daemons in the same domain. When the daemon starts, it binds to this port, provided the node upon which the daemon is running is configured to be an MCP, a managed node, or a peer node. Otherwise, it binds to this port when the node is configured into a domain. Note that the same node can be online in a peer domain, be an MCP of one management domain, and be a managed node in one or more other management domains, simultaneously.

When binding to these ports, the daemon does so in such a manner that packets may be received on any available interface.

RMC client applications use an ephemeral TCP port assigned by the operating system.